SRF2013 - List of Keywords (operation)

Paper	Title	Other Keywords	Page
MOIOA01	The FRIB Project at MSU	cavity, cryomodule, linac, ion	1
	M. Leitner, B. Bird, F. Casagrande, S. Chouhan, C. Compton, J.L. Crisp, K. Elliott, A. Facco, A.D. Fox, M. Hodek, M.J. Johnson, G. Kiupel, I.M. Malloch, D. Miller, S.J. Miller, D. Morris, D. Norton, R. Oweiss, J.P. Ozelis, J. Popielarski, L. Popielarski, A.P. Rauch, R.J. Rose, K. Saito, M. Shuptar, N.R. Usher, G.J. Velianoff, D.R. Victory, J. Wei, J. Whitaker, K. Witgen, T. Xu, Y. Xu, O. Yair, S. Zhao FRIB, East Lansing, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. The Facility for Rare Isotope Beams (FRIB) is ready to start construction. The facility will utilize a high-intensity, heavy-ion driver linac to provide stable ion beams from protons to uranium up to energies of >200 MeV/u and at a beam power of up to 400 kW. The superconducting cw linac consists of 330 individual low-beta (β = 0.041, 0.085, 0.29, and 0.53 at 80.5 MHz and 322 MHz) cavities in 49 cryomodules operating at 2 K. This paper discusses the current development status of the project with emphasis on the linac SRF acquisition. SRF coldmass and cryomodule component designs are briefly summarized. A SRF production facility, currently under construction, is described.
	Slides MOIOA01 [9.804 MB]

MOIOA04	SRF Challenges for Energy Recovery Linacs	cavity, SRF, HOM, linac	24
	A. Burrill HZB, Berlin, Germany
	Many of the challenges associated with operating a SRF ERL are independent of the choice of operating frequency, beam energy, and overall purpose of the machine. Worldwide there are an increasing number of ERLs in various stages of development and operation which are facing a number of similar challenges and often solving them in very different ways. In this talk I will seek to summarize the main challenges the community as a whole faces, address how different laboratories are working to solve these problems, and seek to identify areas of overlap where the community can work together to solve some of these common problems.
	Slides MOIOA04 [5.213 MB]

MOIOB01	High Power Proton/Deuteron Accelerators	linac, SRF, proton, cavity	35
	J.-L. Biarrotte IPN, Orsay, France
	High power proton and deuteron linear accelerators can give rise to a large variety of scientific applications, useful for both fundamental and applied research. Thanks to the on-going efficient development of the superconducting RF technology, more and more projects based on such machines have emerged during the last 2 decades. This paper will review these existing high power proton/deuteron accelerator facilities or projects, trying in particular to emphasize in each case the various specificities and challenges related to the SRF technology.
	Slides MOIOB01 [4.474 MB]

MOIOC01	Heat Transfer at the Interface Between Niobium and Liquid Helium for 6 GHz SRF Cavities	cavity, niobium, interface, coupling	57
	V. Palmieri INFN/LNL, Legnaro (PD), Italy
	Cavity Thermal Boundary Resistance is something extremely complex and not completely understood by the theory. Often identified with the Kapitza resistance or with the Khalatnikov acoustic phonon mismatch at the interface metal-liquid Helium, it depends on so many different and uncontrolled parameters, that its interpretation is not covered by a complete treatise of the phenomenon. Therefore, 99% of the literature on superconducting cavities worries about the cavity interior surface state,while almost nothing is reported on treatments applied to the exterior. In the authors opinion, there is a lack in experimental data analysis due to the fact that the cavity is often considered as a whole adiabatic entity interacting only with RF fields. On the contrary, the cavity is immersed in liquid Helium and the cavity behavior cannot prescind from its thermal properties. Indeed in the normal state He-I has poor thermal conductivity and high specific heat. Moreover the heat exchange at HeII obeys to further mechanisms besides the phonon mismatch. Driven by the hypothesis that thermal losses are dominant for ultraclean cavities, we have collected a plethora of surprising experimental results.
	Slides MOIOC01 [15.558 MB]

MOP003	Implications of Increased Beam Current for the Diamond Storage Ring RF System	cavity, storage-ring, cathode, linac	73
	C. Christou, A. Bogusz, P. Gu, M. Maddock, P.J. Marten, S.A. Pande, A.F. Rankin, D. Spink, A.V. Watkins Diamond, Oxfordshire, United Kingdom
	Diamond Light Source presently operates for users with 300mA beam current and initial tests have begun to upgrade this current towards an ultimate goal of 500mA. The implications of such a beam current increase for the storage ring RF system will be significant, including the installation of a third superconducting cavity and a possible modification of the coupling parameters of the existing cavities. An overview of the planned enhancements of the RF system is presented, including an update of the procurement of a new CESR-design cavity and options for installation and operation of this cavity and supporting infrastructure.

MOP007	The Status of Superconducting Linac and SRF Activities at the SNS	linac, cryomodule, cavity, SRF	83
	S.-H. Kim, W. Blokland, M.S. Champion, A. Coleman, M.T. Crofford, M. Doleans, D.L. Douglas, T.V. Gorlov, M.P. Howell, Y.W. Kang, A.P. Shishlo, S.E. Stewart, W.H. Strong ORNL, Oak Ridge, Tennessee, USA R. Afanador, B. DeGraff, B.S. Hannah, S.W. Lee, C.J. McMahan, T.S. Neustadt, S.W. Ottaway, C.C. Peters, J. Saunders, D.M. Vandygriff ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. There have been substantial gains at the Spallation Neutron Source (SNS) in last 7 years in understanding pulsed superconducting linac (SCL) operation including system and equipment limiting factors and resolution of system and equipment issues. Significant effort and focus are required to assure ongoing success of the operation, maintenance and improvement of the SCL, and to address the requirements of the upgrade project in the future. The SNS is taking a multi-faceted approach to maintaining and improving its linac. A balanced set of facilities which support processing, assembly, repair, and testing of cavities/cryomodules are currently being placed into service. This paper summarizes the status of the SNS SCL and related superconducting radio-frequency (SRF) activities such as development of ASME code-stamped spare cryomodules, R&D activities for SRF cavity performance improvements, SRF cavity development for power upgrade project and SRF facility development/upgrade to support all required activities.

MOP010	Spiral2 Cryomodules B Tests Results	cryomodule, cavity, linac, alignment	95
	G. Olry, F. Chatelet, C. Commeaux, N. Gandolfo, D. Grolet, C. Joly, J. Lesrel, D. Longuevergne, R. Martret, G. Michel, L. Renard, A. Stephen, P. Szott IPN, Orsay, France P.-E. Bernaudin, R. Beunard, R. Ferdinand, A. Lefevre GANIL, Caen, France Y. Gómez Martínez LPSC, Grenoble Cedex, France
	Assembly and tests of the SPIRAL2 superconducting linac's cryomodules at CEA/Saclay and IPN/Orsay have now reached cruising speed after having faced a series of problems, among them contamination. 19 cryomodules are composing the whole Linac and IPN Orsay is in charge of the 7 cryomodules B, housing two 88MHz, beta 0.12 Quarter-Wave Resonators. Two cryomodules have been successfully assembled and tested up to the nominal gradient of 6.5 MV/m for all cavities with also total cryogenic losses under specifications. One of them is fully qualified and has been already delivered to GANIL. The second one showed misalignment on one cavity which could lead to partial disassembly. This paper will present the results of those cryomodules tests as well as the status of the remaining ones.

MOP012	Completion of the Superconducting Heavy Ion Linac at Inter-University Accelerator Centre	linac, electronics, ion, controls	103
	A. Rai, R. Ahuja, J. Antony, S. Babu, J. Chacko, G.K. Chaudhari, A. Chaudhary, T.S. Datta, R.N. Dutt, S. Ghosh, R. Joshi, D. Kanjilal, S. Kar, J. Karmakar, M. Kumar, R. Kumar, D.S. Mathuria, R. Mehta, K.K. Mistri, A. Pandey, P. Patra, P.N. Prakash, A. Roy, J. Sacharias, B.K. Sahu, A. Sarkar, S.S.K. Sonti, S. K. Suman, J. Zacharias IUAC, New Delhi, India
	The Superconducting heavy ion Linac at Inter University Accelerator Centre (IUAC), New Delhi has been delivering accelerated ion beams to the users since 2009 . Initially the first accelerating module, housing eight Quarter Wave Resonators (QWR’s), became operational together with the Superbuncher having one and the Rebuncher having two QWR’s, respectively. In the subsequent years, the remaining two modules have been installed and commissioned. The complete Linac was operated recently and several ion beams were delivered for scheduled experiments. The maximum energy gain was 8 MeV per charge state. Operational highlights include successful operation of four resonators in the third module with Piezo based * mechanical tuning, implementation of remote phase locking for all resonators in three modules, development of a scheme for auto locking of resonators and testing of a capacitive pickup as a beam diagnostic element. Details will be presented vis-à-vis the problems encountered and the future course of action. * A. Rai et. al., Proc. of SRF2009 Sept. 20–25, 2009, Berlin, Germany, page 244. ** B.K.Sahu et. al., Proc. of IPAC 2010, Kyoto Japan, page 2920.

MOP013	SRF Developments at MSU for FRIB	solenoid, cavity, shielding, cryomodule	106
	K. Saito, N.K. Bultman, F. Casagrande, S. Chouhan, C. Compton, K. Elliott, A. Facco, M.J. Johnson, S. Jones, M. Leitner, S.J. Miller, R. Oweiss, J.P. Ozelis, J. Popielarski, L. Popielarski, S. Shanab, J. Wei, T. Xu, Y. Yamazaki, Y. Zhang, Z. Zheng FRIB, East Lansing, Michigan, USA S.K. Chandrasekaran MSU, East Lansing, USA K. Hosoyama KEK, Ibaraki, Japan
	FRIB has built up a new SRF development group for future SRF research and development at MSU. This paper will report on the present status of development for fundamental couplers, pneumatic tuners for HWR, magnetic shielding and superconducting solenoids, barrel polishing techniques for HWR, a cavity steam cleaning method, and niobium material characterization efforts.

MOP018	Design of the MYRRHA 17-600 MeV Superconducting Linac	linac, cavity, lattice, simulation	129
	J.-L. Biarrotte IPN, Orsay, France F. Bouly CERN, Geneva, Switzerland J.-P. Carneiro Fermilab, Batavia, USA D. Uriot CEA/DSM/IRFU, France D. Vandeplassche SCK•CEN, Mol, Belgium
	Funding: This work is being supported by the European Atomic Energy Community’s (EURATOM) Seventh Framework Programme under grant agreement n°269565 (MAX project). The goal of the MYRRHA project is to demonstrate the technical feasibility of transmutation in a 100MWth Accelerator Driven System (ADS) by building a new flexible irradiation complex in Mol (Belgium). The MYRRHA facility requires a 600 MeV accelerator delivering a maximum proton flux of 4 mA in continuous operation, with an additional requirement for exceptional reliability. This paper will briefly describe the beam dynamics design of the main superconducting linac section which covers the 17 to 600 MeV energy range and requires enhanced fault-tolerance capabilities.

MOP020	Progress of the LUNEX5 Project	FEL, laser, electron, undulator	133
	P. Marchand, C. Benabderrahmane, L. Cassinari, M.-E. Couprie, J. Daillant, M. Diop, M.E. El Ajjouri, N. Hubert, M. Labat, R. Lopes, A. Loulergue, M. Louvet, O. Marcouillé, J.L. Marlats, C. Miron, P. Morin, A. Nadji, F. Ribeiro, P. Roy, K. Tavakoli SOLEIL, Gif-sur-Yvette, France S. Bielawski, C. Evain, E. Roussel, C. Szwaj PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France B. Carré, D. Garzella CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France N. Delerue LAL, Orsay, France G. Devanz, M. Luong CEA/DSM/IRFU, France A. Dubois, J. Lüning CCPMR, Paris, France G. Lambert, R. Lehe, A. Lifschitz, V. Malka, A. Rousse, C. Thaury LOA, Palaiseau, France
	LUNEX5 (free electron Laser Using a New accelerator for the Exploitation of X-ray radiation of 5th generation) aims at investigating the production of short, intense, and coherent pulses in the soft X-ray region. It comprises two types of accelerators connected to a single Free Electron Laser (FEL), enabling the most advanced seeding configurations : High order Harmonic in Gas (HHG) seeding and Echo Enable Harmonic Generation (EEHG) with cryogenic in-vacuum undulators. The 400 MeV Conventional Linear Accelerator (CLA) uses superconducting cavities, compatible with a future upgrade towards high repetition rate for investigating advanced FEL schemes. It will also enable multi-user operation by splitting part of the macropulse to different FEL lines. A 0.4 - 1 GeV Laser Wake Field Accelerator (LWFA) will also be qualified in view of FEL applications, in the single spike or seeded regime. After the Conceptual Design Report, R&D has been launched on a cryo-ready 3 m long in-vacuum undulator, variable strong permanent magnet quadrupoles, Smith-Purcell and electro-optics diagnostics. A test experiment is also under preparation for validating the computed beam transport from the LWFA.

MOP029	Cryo-Losses Measurements of the XFEL Prototype and Pre-Series Cryomodules	cryomodule, cryogenics, electron, linac	162
	S. Barbanotti, J. Eschke, K. Jensch, W. Maschmann, O. Sawlanski DESY, Hamburg, Germany W. Gaj, L.M. Kolwicz-Chodak, W. Maciocha IFJ-PAN, Kraków, Poland X. Wang ESS, Lund, Sweden
	Cryo-losses measurements of the XFEL prototype and pre-series cryomodules are here presented and compared with the XFEL requirements. Cryo-losses at the 4.5 K, 80 K and 2K temperatures are calculated during the test period at CMTB (CryoModule Test Bench) at DESY to qualify the cryomodules before installation. This paper summarizes the test procedure for the different circuits (2K, 4.5K, 80K) and in different load conditions: static losses, losses due to the magnet and dynamic losses due to the RF power sent to the cavities at different MV/m levels.

MOP031	Quality Control of the Vessel and Cold Mass Production for the 1.3 GHz XFEL Cryomodules	vacuum, controls, cryomodule, cavity	168
	S. Barbanotti, H. Hintz, K. Jensch, W. Maschmann DESY, Hamburg, Germany
	The industrial production of one hundred cold masses and vacuum vessels for the 1.3 GHz XFEL cryomodules is now fully in operation. Quality checks at the companies and controls at DESY assure the quality level required for the cryomodule assembly. Verification of the main production steps, non-destructive tests, dimensional controls are performed by DESY personnel before accepting the components. This paper resumes the quality control strategy and the results for the first components produced by the companies.

MOP042	Quality Control and Processes Optimization for the EXFEL Superconducting Cavities Series Production at Ettore Zanon spa	cavity, controls, vacuum, SRF	208
	L. Facci, D. Rizzetto Ettore Zanon S.p.A., Nuclear Division, Schio, Italy G. Corniani Ettore Zanon S.p.A., Schio, Italy A. Matheisen DESY, Hamburg, Germany P. Michelato, L. Monaco INFN/LASA, Segrate (MI), Italy
	The construction of the European XFEL forced the first mass production of Niobium bulk SRF cavities. In this context Ettore Zanon S.p.A. built a fully new facility designed to produce four fully treated and He tank equipped cavities per week, ready to be tested at DESY. The facility already reached the foreseen production rate. The guarantee of the highest quality of the resonators produced requires a very strict quality control plan. At the same time, the requirements of the industrial production in terms of time, cost and productivity must be satisfied. As a consequence processes must be standardized and working times optimized. In the following, after the description of the production facility, we would like to highlight and discuss the strategies and arrangements adopted in the various critical fields (clean room, vacuum, etc.) to ensure the foreseen results. Moreover correlation between cavities performances and production cycle parameters will be investigated and discussed.

MOP048	PED Requirements Applied to the Cavity and Helium Tank Manufacturing	cavity, niobium, linac, controls	227
	A. Schmidt, J. Iversen, A. Matheisen, W. Singer DESY, Hamburg, Germany
	For the European XFEL more than 800 Cavities are manufactured by industrial partners. Each cavity is housed in an individual cryo vessel, the so called helium tank. All vessels are made from titanium and manufactured by industry as well. The cavity, welded into its helium tank, is a pressure loaded part and has to follow the pressure equipment directive - PED (97/23/EC). Setting up a series production of cavities and helium tanks by different vendors according given standards, was the task of the EXFEL WPG-1 LINAC-WP04. In cooperation with the TUEV-Nord as the notified body, DESY is responsible for the qualification of design, material in use and reasonable tests to get a certificate for pressure bearing parts.

MOP054	Tests of the Accelerating Cryomodules for the European X-Ray Free Electron Laser	cryomodule, cryogenics, cavity, radiation	244
	M. Wiencek, B. Dzieza, W. Gaj, D. Karolczyk, K. Kasprzak, L.M. Kolwicz-Chodak, A. Kotarba, A. Krawczyk, K. Krzysik, W. Maciocha, A. Marendziak, K. Myalski, S. Myalski, T. Ostrowicz, B. Prochal, M. Sienkiewicz, M. Skiba, J. Świerbleski, J. Zbroja, A. Zwozniak IFJ-PAN, Kraków, Poland
	The European X-ray Free Electron Laser (XFEL) is currently under construction in Germany in Hamburg area. A 2.1 km long superconducting linear accelerator, part of the XFEL, consists of 101 accelerating cryomodules. The XFEL cryomodule is assembled with eight superconducting RF cavities, one cold magnet and Beam Position Monitor (BPM). The cryomodules are tested in dedicated test facility before installation in the XFEL tunnel. The testing procedures for the cryomodules were prepared with use of DESY expertise from TTF (Tesla Test Facility) Collaboration and FLASH (Freie-Elektronen-Laser in Hamburg). This paper describes the full set of testing procedure and incoming and outgoing inspections as well.

MOP061	75 mA Operation of the Cornell ERL Superconducting RF Injector Cryomodule	HOM, SRF, cryomodule, cavity	259
	M. Liepe, B.M. Dunham, R.G. Eichhorn, G.H. Hoffstaetter, R.P.K. Kaplan, P. Quigley, E.N. Smith, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work is supported by the National Science Foundation (Grant No. DMR-0807731). Cornell University has developed a SCRF injector cryomodule for the acceleration of high current, low emittance beams in continuous wave operation. This cryomodule is based on 1.3 GHz superconducting RF technology, and has been tested extensively in the Cornell ERL injector prototype with world record CW beam currents exceeding 70 mA. High CW RF power input couplers and strong Higher-Order-Mode damping in the cavities are essential for high beam current operation. This paper summarizes the performance of the cryomodule during the high beam current operation.

MOP062	Production of 500 MHz SRF Modules the KEKB-type for Taiwan Photon Source	SRF, cavity, niobium, vacuum	263
	Ch. Wang, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Y.-H. Lin, Z.K. Liu, C.H. Lo, M.H. Tsai, T.-T. Yang, M.-S. Yeh, T.-C. Yu NSRRC, Hsinchu, Taiwan T. Furuya, K. Hara, T. Honma, A. Kabe, Y. Kojima, S. Mitsunobu, Y. Morita, H. Nakai, K. Nakanishi, M. Nishiwaki, S. Takano KEK, Ibaraki, Japan F. Inoue, K. Sennyu, T. Yanagisawa MHI, Hiroshima, Japan
	The KEKB-type single-cell 500-MHz superconducting radio frequency (SRF) modules have been selected to power the 3 GeV, 500 mA, storage ring of the constructing Taiwan Photon Source (TPS) at National Synchrotron Radiation Research Center (NSRRC). The design target is to routinely deliver RF forward power up to 300 kW, CW, to single SRF module with highly reliable operation. Three sets of SRF modules have been successfully produced under a tight collaboration with High Energy Accelerator Research Organization (KEK) and Mitsubishi Heavy Industries Ltd. (MHI), after obtaining the technology transfer from KEK. MHI is responsible for the mechanical fabrication and cryo-module assembly, KEK for the surface and RF treatments of the niobium cavities, high power input couplers and HOM dampers and for the liquid-helium tests of the cryo-modules, and NSRRC for the electronic/diagnostic system, final assembly and system integration, high power horizontal test, and reliable test. This work reports the results obtained during the production of these three SRF modules at KEK and NSRRC.

MOP063	Mature Operation of CESR-Type 500-MHz SRF Module at Taiwan Light Source	SRF, vacuum, cavity, cryogenics	266
	Ch. Wang, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Y.-H. Lin, Z.K. Liu, C.H. Lo, M.H. Tsai, T.-T. Yang, M.-S. Yeh, T.-C. Yu NSRRC, Hsinchu, Taiwan
	The Cornell-type 500-MHz SRF module has been routinely operated since the end of 2004 to power the 1.5 GeV Taiwan Light Source with 360 mA in top-up mode. A new record of SRF operation with mean time between failures (MTBF)up to 800 hr has been achieved in the 1st half of 2013 that is compatible with the best operational record of room temperature cavities ever made in the same machine. To meet the user’s strict requirements on highly operational reliability, developing in advanced diagnostic instrumentation together with user-friendly event logging software does never stop. Here, we review our SRF operational experience in last 9 years.

MOP064	Operational Experience with the SOLEIL Superconducting RF System	cavity, cryogenics, HOM, vacuum	269
	P. Marchand, J.P. Baete, R.C. Cuoq, H.D. Dias, M. Diop, J.L. Labelle, R. Lopes, M. Louvet, C.M. Monnot, S. Petit, F. Ribeiro, T. Ruan, R. Sreedharan, K. Tavakoli SOLEIL, Gif-sur-Yvette, France
	In the SOLEIL storage ring, two cryomodules provide to the electron beam an accelerating voltage of 3-4 MV and a power of 575 kW at 352 MHz. Each cryomodule contains a pair of superconducting cavities, cooled with liquid Helium at 4K, which is supplied by a single 350 W cryogenic plant. The RF power is provided by 4 solid state amplifiers, each delivering up to 180 kW. The parasitic impedances of the high order modes are strongly mitigated by means of four coaxial couplers, located on the central pipe connecting the two cavities. Seven years of operational experience with this system as well as its upgrades are reported.

MOP070	Results on Quality Factors of 1.3 GHz Nine-Cell Cavities at DESY	cavity, factory, niobium, linear-collider	297
	F. Schlander IKP, Mainz, Germany F. Schlander DESY, Hamburg, Germany
	Superconducting cavities made of niobium are the basis of many particle accelerators around the world. Besides the quest for high accelerating fields for projects like European XFEL and the International Linear Collider, the quality factor, a measure for the resistance and hence the ohmic losses, is of importance, as it eventually determines the cryoplant size and its costs of operation. Especially for accelerators operating in continuous wave mode, the dynamic heat load generated by cavity operation exceeds the static heat load by far and thus requires minimisation. To investigate the current quality factor performance of 1.3 GHz cavities at DESY, the test results of some 50 recent cavities with state-of-the-art treatment have been examined regarding surface treatment and material.
	Slides MOP070 [0.590 MB]

MOP078	Horizontal Testing of a Dressed Deflecting Mode Cavity for the APS Upgrade Short Pulse X-Ray Project	cavity, controls, photon, vacuum	321
	J.P. Holzbauer, N.D. Arnold, T.G. Berenc, D.J. Bromberek, J. Carwardine, N.P. Di Monte, J.D. Fuerst, A.E. Grelick, D. Horan, J.A. Kaluzny, J.W. Lang, H. Ma, T.L. Mann, D.A. Meyer, M.E. Middendorf, A. Nassiri, Y. Shiroyanagi, J.H. Vacca, G.J. Waldschmidt, R.D. Wright, G. Wu, Y. Yang, A. Zholents ANL, Argonne, USA E.R. Harms, W. Schappert Fermilab, Batavia, USA J.D. Mammosser JLAB, Newport News, Virginia, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CHI1357. The short pulse x-ray (SPX) part of the Advanced Photon Source (APS) Upgrade is an effort to enhance time-resolved experiments on a few-ps-scale at the APS. The goal of SPX is the generation of short pulses of x-rays for pump-probe time-resolved capability using superconducting rf (SRF) deflecting cavities. These cavities will create a correlation between longitudinal position in the electron bunch and vertical momentum. The light produced by this bunch can be passed through a slit to produce a pulse of light much shorter (1-2 ps instead of 100 ps) than the bunch length at reduced flux. An SPX cavity has been tested with a helium vessel and tuner. In addition to studying rf performance with more realistic cooling, this test allowed integration and operation of many systems designed for SPX cryomodule in-ring operation. These systems included an APS-constructed 5 kW, 2.815 GHz amplifier, a digital low-level rf controller system designed and fabricated in collaboration with LBNL, a cavity tuner, and instrumentation systems designed for the existing APS infrastructure. Cavity performance and subsystem performance will be reported and discussed in this paper. A. Zholents et al., NIM A 425, 385 (1999). ** A. Nassiri et al., “Status of the Short-Pulse X-Ray Project at the Advanced Photon Source,” IPAC 2012, New Orleans, LA, May 2012.

MOP080	Design of a New Horizontal Test Cryostat for SCRF Cavities at the Uppsala University	cavity, cryomodule, radiation, vacuum	328
	T. Junquera, P. Bujard, N.R. Chevalier, J.P. Thermeau Accelerators and Cryogenic Systems, Orsay, France L. Hermansson, M. Noor, R.J.M.Y. Ruber, R. Santiago Kern Uppsala University, Uppsala, Sweden H. Saugnac IPN, Orsay, France
	At Uppsala University, the FREIA facility for research and development of new accelerators and associated instrumentation, is presently in construction. Associated to a new Helium Liquefier, a Horizontal Test Cryostat will be used for high power RF tests of completely equipped SC cavities. This paper presents the main characteristics of the cryostat and the associated cryogenic distribution system. Two types of cavities have been considered for test purpose: SC elliptical cavities for future free electron lasers and SC cavities for high intensity proton accelerators (i.e. SC spokes). A special valve box including a subcooling stage and power coupler cooling with supercritical Helium supply have been designed, for temperature operation ranging from 2K to 4.2 K. This facility will play an essential role in the development and test of cavities, couplers and cryomodules for the ESS project. High power RF sources will be installed in order to allow unique and complete tests of spoke cavities and cryomodules at high nominal peak power.

MOP081	Preliminary Studies of the Cryogenic Refrigerator and Distribution Systems for the MYRRHA Proton Linac	cryogenics, linac, cryomodule, proton	331
	T. Junquera, N.R. Chevalier, J.P. Thermeau Accelerators and Cryogenic Systems, Orsay, France L. Medeiros Romão, D. Vandeplassche SCK•CEN, Mol, Belgium H. Saugnac IPN, Orsay, France
	Funding: Work supported by the EU, FP7 MAX contract number 269565 In the framework of recent European programs (FP6-Eurotrans, FP7-MAX), the SC proton Linac for the MYRRHA project (associating an accelerator to a subcritical nuclear reactor, to be installed in the SCK•CEN at Mol-Belgium), has been extensively studied and optimized to reach strict requirements in beam power and reliability as needed for this ADS demonstrator. The linac, composed of 150 SC cavities (CH, spoke and elliptical) installed in 60 cryomodules, operates at 2K, delivering a beam power of 2.5 MW (600 MeV, 4 mA) in CW mode, will be installed in a tunnel of 240 m length. In this paper we present the evaluation of the cryogenic power requirements, a preliminary architecture of the cryogenic refrigerator system including all its major components, and preliminary proposals for the cryofluids distribution along the SC linac.

MOP082	Development and Test of a New Cryostat Module for the Injector of the S-DALINAC*	electron, vacuum, cavity, linac	334
	T. Kürzeder, J. Conrad, F. Hug, N. Pietralla, A. Richter, S.T. Sievers TU Darmstadt, Darmstadt, Germany R.G. Eichhorn Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: *This work is supported by the DFG through the Collaborative Research Center SFB 634. The present injector of the superconducting Darmstadt electron linear accelerator S-DALINAC provides an electron beam of up to 10 MeV kinetic energy and up to 60 μA current in continuous wave operation. A new cryostat module has been constructed to replace the actual one in order to provide higher beam energies of up to 14 MeV and currents of up to 250 μA for nuclear resonance fluorescence experiments at the Darmstadt High Intensity Photon Setup (DHIPS). As before two 20-cell superconducting microwave cavities will be operated at an acceleration frequency of 3 GHz in a liquid helium bath at 2 K. For the injector upgrade two new elliptical 20-cell niobium cavities were also manufactured and in addition a third spare one. The rf power is transferred to the cavities by an also newly developed waveguide-transition line and input couplers. We report on the construction of the cryostat module and its components and present the results of a first cooling-down procedure.

MOP083	Operational Experience With the SOLEIL Storage Ring RF Cryogenic Plant	cryogenics, controls, cavity, HOM	337
	M. Louvet, H.D. Dias, M. Diop, P. Marchand SOLEIL, Gif-sur-Yvette, France
	In the Storage Ring of the Synchrotron SOLEIL light source, two cryomodules provide the required power of 575 kW at the nominal energy of 2.75 GeV with the full beam current of 500 mA and all the insertion devices. Each cryomodule contains a pair of 352 MHz superconducting cavities (Nb/Cu), cooled in a bath of liquid helium at 4.5 K. A single 350 W cryogenic system supplies the liquid helium for the two cryomodules. The seven years of operational experience with this cryogenic plant as well as its upgrades are reported.

MOP084	ESS Cryomodules for Elliptical Cavities	cryomodule, vacuum, cryogenics, cavity	341
	G. Olivier, J.P. Thermeau IPN, Orsay, France P. Bosland CEA/IRFU, Gif-sur-Yvette, France C. Darve ESS, Lund, Sweden
	The European Spallation Source will be the world's most powerfull neutron source. IPN Orsay undertakes the development of the ESS linac cryomodules for both medium and high beta elliptical cavities which constitute the high energy section. A medium beta technical demonstrator will be built in a first time. The cryomodules are composed of 4 superconducting cavities cooled at 2K. The cold mass assembly is hanged in an intermediate structure located inside the vacuum vessel. A 50K fixed temperature is implemented by the mean of an aluminium shield. Each cryomodule is connected to the cryogenic distribution line. The vacuum vessel is 6.3m long and has a 1.2m diameter. The poster describes the general design,the solutions implemented, the characteristics of the main components and the mechanical/thermal calculations .

MOP085	Status of the Superconducting Proton Linac (SPL) Cryomodule	cavity, vacuum, cryogenics, linac	345
	V. Parma, R. Bonomi, O. Capatina, J.K. Chambrillon, E. Montesinos, K.M. Schirm, A. Vande Craen, G. Vandoni, R. van Weelderen CERN, Geneva, Switzerland G. Devanz CEA/IRFU, Gif-sur-Yvette, France P. Duchesne, P. Duthil, S. Rousselot IPN, Orsay, France
	The Superconducting Proton Linac (SPL) is an R&D effort conducted by CERN in partnership with other international laboratories, aimed at developing key technologies for the construction of a multi-megawatt proton linac based on state-of-the-art SRF technology. Such an accelerator would serve as a driver in new physics facilities for neutrinos and/or radioactive ion beams. Amongst the main objectives of this effort, are the development of 704 MHz bulk niobium β=1 elliptical cavities (operating at 2 K and providing an accelerating field of 25 MV/m) and the test of a string of cavities integrated in a machine-type cryo-module. In an initial phase, only four out of the eight cavities of the SPL cryo-module will be tested in a half- length cryo-module developed for this purpose, which nonetheless preserves the main features of the full size machine. This paper presents the final design of the cryo-module and the status of the construction of the main cryostat parts. Preliminary plans for the assembly and testing of the cryo-module at CERN are presented and discussed.

MOP089	Design of the ESS Spoke Cryomodule	vacuum, cryomodule, cavity, cryogenics	357
	D. Reynet, S. Bousson, S. Brault, P. Duchesne, P. Duthil, N. Gandolfo, G. Olry, E. Rampnoux IPN, Orsay, France
	The European Spallation Source (ESS) project brings together 17 European countries to develop the world’s most powerful neutron source feeding multidisplinary researches. The superconducting part of the linear accelerator consists in 59 cryomodules housing different superconducting radiofrequency (SRF) resonators among which 28 paired β=0.5 352.2 MHz SRF niobium double Spoke cavities, held at 2K in a saturated helium bath. A prototype Spoke cryomodule with two cavities equipped with their 300kW RF power couplers is now being designed and will be constructed and tested at full power by the end of 2015 for the validation of all chosen technical solutions. It integrates all the interfaces necessary to be operational within a linac machine. Its assembly requires dedicated tooling and procedures in and out of a clean room. The design takes into account an industrial approach for the management of the fabrication costs. This prototype will have to guarantee an accelerating field of 8MV/m while optimizing the energy consumption and will aim at assessing the maintenance operations issues. We propose to present the design of this cryomodule and its related tooling.

MOP092	Computation of Wakefields and HOM Port Signals by Means of Reduced Order Models	wakefield, impedance, cavity, HOM	364
	J. Heller, T. Flisgen, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	The investigation of wakefields is an important task in the design and operation of particle accelerators. Computer simulations are a reliable tool to extend the understanding of these effects. This contribution presents an application example of a new method to compute wakefields as well as parameters derived from those fields, such as higher order mode (HOM) port signals. The method is based on a reduced order model of the structure created by as set of 3D eigenmodes, a set of 2D waveguide port modes and the current density of the beam. In contrast to other wakefield computations, the proposed method operates directly on the reduced order model. Therefore, once having established this model, the beam-excited fields can be determined quickly for different beam parameters. As a matter of fact, only a small part of the reduced system has to be recomputed for every sweep point. From these advantages it is obvious, that the method is highly compatible for beam parameter studies. In a proof of principal the effectiveness of the method compared to established methods of wakefield computations in terms of computational time and accuracy is shown.

TUP051	Horizontal High Pressure Water Rinsing for Performance Recovery	cavity, cryomodule, vacuum, factory	527
	Y. Morita, K. Akai, T. Furuya, A. Kabe, S. Mitsunobu, M. Nishiwaki KEK, Ibaraki, Japan
	Eight superconducting accelerating cavities were operated for more than ten years at the KEKB machine. Those cavities are also used at SuperKEKB. During the KEKB operation, Q values of some cavities were degraded. Cause of the degradation was contamination by air dusts at a repair of vacuum seals or a gasket replacement of input couplers. So far, those degradations are acceptable for the SuperKEKB operation, however, further degradation will make the operation unstable and, in the worst case, make it impossible. High pressure rinsing (HPR) is an effective method to clean the cavity surface. In order to apply HPR, however, the cavity has to be disassembled from a cryomodule. The disassembly takes time and costs. Furthermore, re-sealed vacuum flanges bring the risk of vacuum leakage again. Therefore we have developed a horizontal HPR. This method applies a high pressure water jet that is inserted horizontally into the cavity in the cryomodule. The wasted water is extracted with an aspirator. This method does not require the disassembly. We applied the horizontal HPR to our degraded cavity. Its RF performance has been successfully recovered.

TUP062	Application of In-Vacuum Infrared Pyrometry During Fabrication of European XFEL Niobium Cavities	cavity, vacuum, electron, niobium	570
	L. Monaco, P. Michelato, D. Sertore INFN/LASA, Segrate (MI), Italy V. Battista, G. Corniani, M. Festa Ettore Zanon S.p.A., Schio, Italy C. Pagani Università degli Studi di Milano & INFN, Segrate, Italy
	A technique to measure the temperature of Niobium components in vacuum during Electron Beam Welding (EBW) operation is presented and results obtained on the large scale cavity production for the European XFEL are discussed. During the EBW process, the knowledge of the components temperature during the welding operation could help both for the better choice of the welding parameters and for the optimization of the production cycle. In collaboration with the Italian firm Ettore Zanon (EZ), we developed a system able to measure the temperature of Nb components in vacuum during EBW operation using a IR pyrometer placed outside the vacuum chamber through an appropriate vacuum viewport. In the paper the experience of this device during the production of Nb components for the XFEL 1.3 GHz cavity production is discussed.

TUP069	The Copper Substrate Developments for the HIE-ISOLDE High-Beta Quarter Wave Resonator	cavity, electron, cryogenics, linac	596
	L. Alberty, G. Arnau-Izquierdo, I. Aviles Santillana, S. Calatroni, O. Capatina, A. D'Elia, G. Foffano, Y. Kadi, P. Moyret, K.M. Schirm, T. Tardy, W. Venturini Delsolaro CERN, Geneva, Switzerland A. D'Elia UMAN, Manchester, United Kingdom
	A new linac using superconducting quarter-wave resonators (QWR) is under construction at CERN in the framework of the HIE-ISOLDE project. The QWRs are made by Niobium sputtered on a bulk Copper substrate. The working frequency at 4.5 K is 101.28 MHz and they will provide 6 MV/m accelerating gradient on the beam axis with a total maximum power dissipation of 10 W. The properties of the cavity substrate have a direct impact on the final cavity performance. The Copper substrate has to ensure an optimum surface for the Niobium sputtered layer. It has also to fulfill the required geometrical tolerances, the mechanical stability during operation and the thermal performance to optimally extract the RF dissipated power on cavity walls. The paper presents the mechanical design of the high β cavities. The procurement process of the Copper raw material is detailed, including specifications and tests. The manufacture sequence of the complete cavity is then explained and the structural and thermo-mechanical behavior during the tests performed on a prototype cavity is discussed. The industrialization strategy is presented in view of final production of the cavities.

TUP072	Quality Factor Measurements of the Ultramet 3 GHz Cavity Constructed Using Chemical Vapour Deposition	cavity, niobium, SRF, radio-frequency	607
	D.L. Hall, D. Gonnella, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA V.M. Arrieta, S.R. McNeal Ultramet, California, USA
	Funding: US Department of Energy Phase 1 Small Business Innovation Research award to Ultramet A seamless 3 GHz bulk niobium cavity constructed by Ultramet using rapid chemical vapor deposition (CVD) techniques has been tested on the vertical SRF test stand at Cornell. The cavity received a 25 um buffered chemical polish (BCP) and 700 C heat treatment for 4 days. First test results gave an intrinsic quality factor of Q0 = (1.55 ± 0.12) x 10⁷ and (2.00 ± 0.15) x 10⁷ at 4.2 K and 1.5 K, respectively. A second BCP removed 100 um of material, after which test results improved to Q0 = (7.59 ± 1.52) x 10⁷ and (4.16 ± 0.31) x 10⁸ at 4.2 K and 1.5 K. During the ﬁrst test poor coupling to the input ampliﬁer impeded tests at accelerating ﬁelds >0.2 MV/m, while during the second test the cavity quenched at 1.3 MV/m when operating at 1.5 K. An optical inspection of the cavity after the second test revealed the presence of at least 4 pits on the upper hemisphere suggesting an area of higher than average surface resistance that may have contributed to the low ﬁeld quench via thermal runaway. The potential of CVD as a construction method for SRF cavities is discussed.

TUP087	RF Test Results of the first Nb3Sn Cavities Coated at Cornell	cavity, niobium, SRF, linac	666
	S. Posen, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	As an alternative material to niobium for SRF cavities in particle accelerators, Nb3Sn presents two significant advantages. With a Tc of 18 K, it has a very small surface resistance at a given temperature, leading to a significant reduction in cryogenic costs; and with a predicted Hsh of nearly 400 mT, it has the potential to produce cavities with higher gradients and therefore shorter high energy linacs. Recently, two 1.3 GHz cavities have been fabricated and coated with Nb3Sn at Cornell. Tests of these first cavities have produced encouraging results, including a very high Tc and some very high-performing surface regions. These cavity results as well as new results of samples studied using TEM will be presented.

TUP095	Field Emission and Consequences as Observed and Simulated for CEBAF Upgrade Cryomodules	cavity, neutron, electron, radiation	694
	F. Marhauser, R.P. Johnson, R. Rodriguez Muons, Inc, Illinois, USA P. Degtiarenko, A. Hutton, G. Kharashvili, C.E. Reece, R.A. Rimmer JLAB, Newport News, Virginia, USA
	High gamma and neutron radiation levels were monitored at the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Laboratory (JLab) after installation of new cavity cryomodules and initial test runs in the frame of the ongoing 12 GeV upgrade program. The dose rates scaled exponentially with cavity accelerating fields, but were independent of the presence of an electron beam in the accelerator. Hence, field emission (FE) is the source of origin. This has led to concerns regarding the high field operation (100 MV per cryomodule) in the future 12 GeV era. Utilizing supercomputing, novel FE studies have been performed with electrons tracked through a complete cryomodule. It provides a principal understanding of experimental observations as well as ways to mitigate FE as best as practicable by identification of problematic cavities.

TUP100	Medium Field Q-Slope Studies in High Frequency Cavities	cavity, superconductivity, niobium, factory	705
	O.S. Melnychuk, A. Grassellino, A.I. Sukhanov Fermilab, Batavia, USA
	A phenomenon of Medium Field Q-Slope (MFQS) in superconducting RF cavities is of high importance because it occurs in the field range (5-20MV/m) that includes designed operation fields of future CW accelerators. MFQS impacts resistive losses in the cavity and, consequently, directly affects accelerator operation costs. We present studies of MFQS based on vertical test data for 1.3GHz nine-cell cavities and make comparisons of vertical test data from different laboratories.

TUP106	Second-Sound Measurements on a 3 GHz SRF Cavity at Low Acceleration Fields*	cavity, electron, acceleration, scattering	728
	S.T. Sievers, U. Bonnes, C. Burandt, F. Hug, T. Kürzeder, N. Pietralla, A. Richter TU Darmstadt, Darmstadt, Germany
	Funding: *This work is supported by the DFG through the Collaborative Research Center SFB 634. The superconducting Darmstadt electron linear accelerator S-DALINAC uses 20-cell niobium cavities that are operated at a microwave frequency of 3 GHz in liquid helium at a temperature of 2 K. This operation temperature is well below TC = 9.25 K of niobium and guarantees superconducting condition in routine operation. Occasional surface impurities, in particular after venting the beamline following maintenance work, can lead to local quenches which destroy superconductivity of the cavity. In such events it is desirable to have a method for locating and eliminating these surface impurities. In order to locate quench sites in the superconducting cavities during operation in liquid helium a set-up of oscillating superleak transducers (OSTs) was tested in a vertical bath cryostat on a cavity known to quench at very small accelerating fields. Despite the low rf power of approximately 4 W needed to quench the cavity, we were able to identify the quench sites with the OST set-up. Subsequent optical inspection clearly showed surface damages at the determined positions. We will report on our set-up and the procedure.

TUP114	XT-map System for Locating SC Cavity Quench Position	cavity, cryogenics, survey, accelerating-gradient	747
	H. Tongu, Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan H. Hayano, Y. Yamamoto KEK, Ibaraki, Japan
	XT-map system under development in collaboration between Kyoto University and KEK is a combined system of the temperature mapping (T-map) and X-ray mapping (X-map). High resolution T-map at quench detection will give more information for improving yield in production of high performance SC Cavities. The high-density sensor distribution of the XT-map gives the high resolution. Because the huge amount of sensor lines are multiplexed at a hi-speed scanning rate in the vicinity of the sensors, the small number of signal lines makes the installation process easy and reduces the system complexity. The scanning test of this XT-map system has been performed in the vertical test at KEK. The detected quench events will be reported.

THIOA01	Infrastructure, Methods and Test Results for the Testing of 800 Series Cavities for the European XFEL	cavity, coupling, controls, feedback	812
	D. Reschke DESY, Hamburg, Germany
	Funding: The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no 283745 (CRISP). The main linac of the European XFEL will consist of 100 accelerator modules, i.e. 800 superconducting accelerator cavities operated at a design gradient of 23.6 MV/m. The fabrication and surface preparation of the cavities in industry is in full swing. This talk describes the infrastructure and procedures of the vertical acceptance test in the "Accelerator Module Test Facility AMTF" at DESY. The present status of the test results is given.
	Slides THIOA01 [1.998 MB]

THIOA05	Optimization of SRF Linacs	cryomodule, cavity, linac, cryogenics	830
	T. Powers JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. This work describes preliminary results of a new software tool that allows one to vary parameters and understand the effects on the optimized costs of construction plus 10 year operations of an SRF linac, the associated cryogenic facility, and controls, where operations includes the cost of the electrical utilities but not the labor or other costs. It derives from collaborative work done with staff from Accelerator Science and Technology Centre, Daresbury, UK several years ago while they were in the process of developing a conceptual design for the New Light Source project. The initial goal was to convert a spread sheet format to a graphical interface to allow the ability to sweep different parameter sets. The tools also allow one to compare the cost of the different facets of the machine design and operations so as to better understand the tradeoffs. More recent additions to the software include the ability to save and restore input parameters as well as to adjust the Qo versus E parameters in order to explore the potential costs savings associated with doing so.
	Slides THIOA05 [2.712 MB]

THIOC04	Demonstration of RF Stabilities in STF 9-cell Cavities Aiming for the Near Quench Limit Operation	cavity, feedback, LLRF, controls	865
	M. Omet Sokendai, Ibaraki, Japan T. Matsumoto, S. Michizono, T. Miura KEK, Ibaraki, Japan
	In preparation of ILC an operation of two superconducting cavities controlled by digital LLRF techniques at different gradients (16 MV/m, 24 MV/m) with flat flattops and a 6.4 mA beam was demonstrated, which is only possible by PkQL control (individual setting of driving power and loaded Q per cavity). The vector sum stabilities were ΔA/A = 0.009%rms and Δφ = 0.009°rms. Since in ILC the cavity gradient spread is large (31.5 MV/m±20%) the required range of loaded Q values is 3·10⁶ to 10⁷. High loaded Q operation with a 6.1 mA beam at 2·10⁷ was demonstrated. The stabilities were ΔA/A = 0.008%rms and Δφ = 0.014°rms. Furthermore a near klystron operation within 5% of saturation was performed with a 6.2 mA beam. The stabilities were ΔA/A = 0.010%rms and Δφ = 0.009°rms.
	Slides THIOC04 [1.448 MB]

THIOD01	SRF Cavities for ADS Project in China	cavity, linac, SRF, proton	868
	Y. He, W.M. Yue, S.H. Zhang IMP, Lanzhou, People's Republic of China J.P. Dai, Z.Q. Li, Z.C. Liu, W.M. Pan IHEP, Beijing, People's Republic of China X.Y. Lu PKU, Beijing, People's Republic of China
	The driver linac for ADS project in China is full superconducting downstream of Radio Frequecy Quadrupole Accelerator. It is a key technology R&D stage of the project from 2011 to 2015. Superconducting HWR, Spoke, and elliptical cavities are all involved in the project. The prototypes of 162.5 MHz HWR010, 325 MHz Spoke012, 325 MHz Spoke021, 325 MHz Spoke040, and 650 MHz elliptical 063 are being developed at IMP and IHEP in China. A small number of HWR010 and Spoke012 have been produced and vertically tested. The first prototype of Spoke021 were tested too. The design, performances, fabrication, suface processing, and testing of all cavities will be presented in the talk. The design improvement of the cavities in the future will also be discussed.
	Slides THIOD01 [13.465 MB]

THIOD02	Faced Issues in ReA3 Quarter-Wave Resonators and Their Successful Resolution	cavity, vacuum, linac, cryomodule	873
	A. Facco NSCL, East Lansing, Michigan, USA C. Compton, J.L. Crisp, K. Elliott, A. Facco, M. Hodek, M.J. Johnson, M. Leitner, I.M. Malloch, D. Miller, S.J. Miller, D. Morris, D. Norton, R. Oweiss, J.P. Ozelis, J. Popielarski, L. Popielarski, K. Saito, N.R. Usher, G.J. Velianoff, D.R. Victory, J. Wei, K. Witgen, Y. Xu, S. Zhao FRIB, East Lansing, Michigan, USA A. Facco INFN/LNL, Legnaro (PD), Italy
	Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. The 80.5 MHz, β=0.085 QWR production cavities for the ReA3 project at MSU have initially shown puzzling behavior and unexpected lack of performance. This was due to a combination of design problems and subtle mechanical effects which have been pointed out during a brief but intense testing campaign made by the FRIB SRF group. The same cavities could be eventually refurbished and brought to performance well above original specifications. This work will be presented with emphasis to the technical problems encountered, their diagnosis and the adopted solutions.
	Slides THIOD02 [8.256 MB]

THP003	Cold Measurements on the 325 MHz CH-Cavity	cavity, linac, coupling, ion	896
	M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany M. Amberg HIM, Mainz, Germany
	Funding: GSI, BMBF Contr. No. 06FY7102, 06FY9089I At the Institute for Applied Physics (IAP), Frankfurt University, a sc 325 MHz CH-Cavity has been designed and built. This 7-cell cavity has a geometrical beta of 0.16 corresponding to a beam energy of 11.4 AMeV. The design gradient is 5 MV/m. Novel features of this resonator are a compact design, low peak fields, easy surface processing and high power coupling. After successful tests at Research Instruments (RI) and in Frankfurt the cavity was processed and cleaned at RI and power tests at 4K have been performed at the cryo lab in Frankfurt. In this paper these measurements will be presented.

THP004	Design Progress of SSR1 Single Spoke Resonator for RAON	cavity, superconducting-cavity, simulation, acceleration	899
	H.J. Cha, D. Jeon, H.C. Jung, H.J. Kim, G.-T. Park IBS, Daejeon, Republic of Korea R.E. Laxdal, Z.Y. Yao, V. Zvyagintsev TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	Funding: The Ministry of Science, ICT and Future Planning (MSIP) and the National Research Foundation (NRF) of the Republic of Korea under Contract 2011-032011 An advanced heavy ion accelerator for basic sciences and multiple applications, called “RAON”, is under construction in Daejeon, South Korea. The fabrication of prototypes for four different types of superconducting cavities, QWR, HWR, SSR1 and SSR2, is scheduled based on the on-going technical designs. In this paper, we present the electromagnetic and mechanical analyses for the SSR1 cavity (β=0.3 and f=325 MHz). Several variants have been considered and compared in terms of rf parameters, multipacting sensitivity, helium pressure sensitivity and ease of fabrication. This includes an analysis of stiffening rings and helium jacket design for stable operation. The progress towards the design of the SSR1 cavity will be given.

THP005	Characteristics and Fabrication of Spoke Cavities for High-Velocity Applications	cavity, vacuum, target, superconductivity	902
	C.S. Hopper, J.R. Delayen, H. Park ODU, Norfolk, Virginia, USA J.R. Delayen, H. Park JLAB, Newport News, Virginia, USA
	A 500 MHz, velocity-of-light, two-spoke cavity has been designed and optimized for possible use in a compact light source [1]. Here we present the mechanical analysis and steps taken in fabrication of this cavity at Jefferson Lab. *[1] T. Satogata et al, “Compact Accelerator Design for a Compact Light Source,” IPAC13, Shanghai, China, May 2013.

THP012	Rebuild of Capture Cavity 1 at Fermilab	cavity, cryomodule, vacuum, SRF	917
	E.R. Harms, T.T. Arkan, E. Borissov, N. Dhanaraj, A. Hocker, Y.O. Orlov, T.J. Peterson, K.S. Premo Fermilab, Batavia, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The front end of the proposed Advanced Superconducting Test Accelerator at Fermilab employs two single cavity cryomodules, known as ‘Capture Cavity 1’ and ‘Capture Cavity 2’, for the first stage of acceleration. Capture Cavity 1 was previously used as the accelerating structure for the A0 Photoinjector to a peak energy of ~14 Mev. In its new location a gradient of ~25 MV/m is required. This has necessitated a major rebuild of the cryomodule including replacement of the cavity with a higher gradient one. Retrofitting the cavity and making upgrades to the module required significant re-design. The design choices and their rationale, summary of the rebuild, and early test results are presented.

THP017	Mechanical Study on the Cavity Package of 1.3 GHz Superconducting Accelerating Unit at IHEP	cavity, simulation, cryomodule, SRF	926
	S. Jin, J. Gao, Z.C. Liu, J.Y. Zhai, H.J. Zheng IHEP, Beijing, People's Republic of China
	The program of 1.3GHz Superconducting RF (SRF) Accelerating Unit is under study at IHEP. A scheme of the unit structure is shown as fig. 1. In the unit, a 9-cell SRF cavity, tuner and a liquid helium (LHe) tank including a section of 50mm long, 0.3mm thick bellows will be welded and assembled together to form a relatively independent component called cavity package. In the study, mechanical analyses are carried out focusing on the package to assure its safety in the fabrications or other room temperature measurements. A commercial program of ANSYS Workbench is used.

THP024	Lorentz Force Detuning Simulations of Spoke Cavities With Different Stiffening Elements	cavity, simulation, radiation, vacuum	946
	J.L. Muñoz, F.J. Bermejo ESS Bilbao, Zamudio, Spain
	Lorentz force detuning caused by radiation pressure on the Nb cavity walls is of concern in cavity design and operation since its magnitude can approach the cavity bandwidth. This effect can be reduced using pasive stiffening elements in the cavity. In this work, Lorentz force detuning has been studied by numerical simulations for spoke cavities. Different stiffening elements has been considered. Static and dynamic behaviour have been analyzed by means of 3D static and transient electromagnetic and mechanical coupled finite elements simulations.

THP029	Simulation of Mechanical Resonances of SRF Cavities in Low Beam Current CW Operation	cavity, resonance, simulation, cryomodule	962
	N. Solyak, M.H. Awida, I.V. Gonin, T.N. Khabiboulline, Y.M. Pischalnikov, W. Schappert, V.P. Yakovlev Fermilab, Batavia, USA
	The low beam current for CW operation of the Project X requires cavities to be mechanically optimized to operate at a high loaded Q and thus, low bandwidth with higher sensitivity to microphonics. The essential source of microphonics detuning is fluctuations in the helium pressure df/dp. Last year’s several methods for reducing df/dp has been proposed. One of the other possible sources of RF frequency instability is mechanical resonances. The cavity could be driven out of operating frequency by the mechanical deformations due to vibrations caused by external factors. In this paper we present the COMSOL multiphysics algorithm developed for evaluation of operating frequency shift due to mechanical resonances in SC cavities. We discuss the results of simulations for 5-cell elliptical 650 MHz β=0.9 cavities. The comparison of COMSOL simulations and measurements of ILC type cavities in Horizontal Test Stand at Fermilab is presented.

THP033	Study of Balloon Spoke Cavities	cavity, TRIUMF, simulation, proton	972
	Z.Y. Yao, R.E. Laxdal, B.S. Waraich, V. Zvyagintsev TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada R. Edinger PAVAC, Richmond, B.C., Canada
	A balloon geometry has been proposed to suppress multipacting for single spoke resonators. The design may find a useful application for proton and ion accelerator projects. TRIUMF has completed initial RF, mechanical, and fabrication studies on this special geometry for both low (β=0.12) and medium (β=0.3) β geometries. The RF properties are comparable with that of traditional spoke cavities but with improved RF efficiency in addition to the reduced multipacting. The results of electro-magnetic and structural design studies comparing the balloon geometry with traditional spoke geometries will be presented. We will also present optimization studies of the mechanical design, such as decreasing df/dp by EM field compensation as well as discussing tuning strategies and fabrication techniques.

THP034	Multipacting Suppression in a Single Spoke Cavity	cavity, electron, resonance, simulation	975
	Z.Y. Yao, R.E. Laxdal, V. Zvyagintsev TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada X.Y. Lu, K. Zhao PKU, Beijing, People's Republic of China
	Spoke cavities are good candidates for the low and medium β section of a high intensity proton or ion accelerator. For many high intensity accelerators, stability and reliability are the most important properties. Currently, one of the key issues of spoke cavity performance is multipacting, which may cause instability during operation. Multipacting in a spoke cavity has a troublesome characteristic as it presents a continual barrier over a wide gradient range, usually in the range of operation from 3MV/m to 15MV/m. A good surface processing can improve the secondary electron emission yield. However, the complex 3D structure makes it not easily achievable as with the elliptical cavity variants. Suppressing multipacting in the design stage is clearly advantageous. This paper will present a multipacting study based on the PKU-I spoke cavity. A systematic correlation between geometric parameters and multipacting behaviors is obtained. Based on this study a new geometry of single spoke cavity called the ‘balloon’ variant is proposed.

THP046	Magnetic Material Characterization & SC Solenoid Coil Package Design for FRIB	solenoid, shielding, cavity, cryogenics	1009
	K. Saito, S. Chouhan, C. Compton, J. DeKamp, M. Leitner, F. Marti, J.P. Ozelis, S. Shanab, G.J. Velianoff, X. Wu, Y. Yamazaki, A. Zeller, Y. Zhang, Q. Zhao FRIB, East Lansing, Michigan, USA S.K. Chandrasekaran MSU, East Lansing, USA K. Hosoyama KEK, Ibaraki, Japan
	To date SRF technology is extending to large scale heavy ion LINACs, where SRF cavities accelerate beams from very low energy to high energy. In this application, superconducting (SC) solenoids are installed inside the cryomodule to provide strong beam focusing with enhanced space efficiency. FRIB will use local magnetic shielding, where magnetic shielding by Cryoperm or A4K is located close to the cavity at 2K. In this scheme rather strong magnetic fringe fields from the SC solenoid expose the shielding material and will magnetize it. An efficient degaussing process is required as cure against such magnetization. Magnetic material characterization of magnetic shielding materials is very important to be able to plan effective degaussing procedures. The paper will also discuss the design of FRIB solenoids optimized for cost, reliability, and robust long-term operation. NbTi wire performance criteria are discussed in addition to solenoid operational margins.

THP049	SPL RF Coupler Cooling Efficiency	cryomodule, radiation, framework, cavity	1019
	R. Bonomi, O. Capatina, E. Montesinos, V. Parma, A. Vande Craen CERN, Geneva, Switzerland
	Energy saving has become an important challenge in accelerator design. In this framework, reduction of heat loads in a cryomodule is of fundamental importance due to the small thermodynamic efficiency of cooling at low temperatures. In particular, care must be taken during the design of its critical components (RF couplers, cold-warm transitions, ..). In this framework, the main RF coupler of the Superconducting Proton Linac cryomodule at CERN will not only be used for RF powering but also as the main mechanical support of the superconducting cavities. These two functions have to be accomplished while ensuring the lowest heat in-leak to the helium bath at 2 K. In the SPL design, the RF coupler outer conductor is composed of two walls and cooled by forced convection with helium gas at 4.5 K. Analytical, semi-analytical and numerical analyses are presented in order to defend the choice of gas cooling. Temperature profiles and thermal performance have been evaluated for different operating conditions; a sensitivity analysis of RF currents node position along the wall has also been performed. Finally, comparison with respect to other heat extraction methods is presented.

THP053	Development of Quality Control Procedures for the Processing of ReA3 Copper Plated Fundamental Power Coupler	controls, cavity, detector, SRF	1031
	R. Oweiss, J.L. Crisp, A. Facco, M. Leitner, D. Morris, J. Popielarski FRIB, East Lansing, Michigan, USA A. Facco INFN/LNL, Legnaro (PD), Italy L. Popielarski, J. Wenstrom NSCL, East Lansing, Michigan, USA
	The processing of copper plated fundamental power couplers (FPCs) has posed major risks to the successful performance of superconducting cavities. This paper discusses the lessons learnt throughout the development of quality control procedures for the ReA3 copper plated FPCs. Michigan State University (MSU) Re-Accelerator project (ReA3) utilizes eight copper plated coaxial FPCs to power the 80.5 MHz=0.085 quarter-wave resonators (QWRs) for which baseline quality control procedures are established. The effectiveness of visual inspection process using the microscope & borescope to qualify FPC components is evaluated. The adaptive use of quality control diagnostic devices as the liquid particle counter, surface particle detector & desiccator for the clean processing & assembly is assessed. A summary of the collaborative work to refine and optimize FPC design & processing in correlation to cavity performance and experimental results is presented. *This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE SC0000661.

THP056	Validation Procedures for the IFMIF Power Coupler Prototypes	vacuum, controls, target, linac	1043
	H. Jenhani, P. Carbonnier, Y. Gasser, N. Grouas, P. Hardy, V.M. Hennion, F. Orsini, Y. Penichot, B. Renard, D. Roudier CEA/IRFU, Gif-sur-Yvette, France S.J. Einarson, T.A. Treado CPI, Beverley, Massachusetts, USA D. Regidor, M. Weber CIEMAT, Madrid, Spain
	In the framework of the International Fusion Materials Irradiation Facility (IFMIF), which consists of two high power CW accelerator drivers, each delivering a 125 mA deuteron beam at 40 MeV, a Linear IFMIF Prototype Accelerator (LIPAc) is presently under design for the first phase of the project. The first two IFMIF Power Coupler Prototypes were manufactured for LIPAc. Series of acceptance tests have been performed successfully. Prototype Power Couplers have been then cleaned and assembled in an ISO 5 cleanroom. A dedicated test bench allowing RF conditioning of the couplers up to 200 kW CW at 175 MHz was achieved. RF power conditioning is planned to start during October 2013.

THP059	HOM Coupler Design Adjustment for CW operation of the 1.3 GHz 9-cell TESLA Type SRF Cavity	HOM, dipole, cavity, simulation	1051
	D. Kostin, W.-D. Möller, J.K. Sekutowicz DESY, Hamburg, Germany
	One of the key features of a modern research facility is its versatility, ability to adjust for a multitude of the applications and user needs. A challenge for the coming European XFEL is to become a multipurpose laboratory with a broad applications spectrum. Primarily, the XFEL is a pulsed machine. Encompassing the CW mode would be a worthy addition. CW operation of the 1.3GHz 9-cell TESLA Type SRF Cavity was performed several times at DESY and other Labs successfully. One of the difficulties was a heat load of the High Order Mode (HOM) couplers. To amend this HOM coupler design adjustement is proposed, simulated and modelled. Results are presented and discussed.

THP060	High Power RF Coupler for ADS Accelerating Cavities	cavity, simulation, linac, Windows	1055
	S.V. Kutsaev, M.P. Kelly, B. Mustapha, J.A. Nolen, P.N. Ostroumov ANL, Argonne, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357. Accelerator driven systems (ADS) require a high-power CW proton accelerator with proton beam energy near 1 GeV. High-gradient superconducting TEM-cavities are a natural choice for the front end of linac. This paper presents the design of superconducting low-beta half wave resonator operating at 162 MHz frequency for ADS, as well as a new 75 kW power coupler that has been designed at Argonne National Laboratory. This coupler would permit operations with an accelerating voltage of 3.0 MV with a beam current of 25 mA. The coupler includes a cold RF window which keeps the antenna at low temperature and a variable bellows section to adjust the coupling factor. The importance of these features for reliable operation will be discussed in detail.

THP061	Developments of HOM Dampers for SuperKEKB Superconducting Cavity	cavity, HOM, simulation, factory	1058
	M. Nishiwaki, K. Akai, T. Furuya, A. Kabe, S. Mitsunobu, Y. Morita KEK, Ibaraki, Japan
	Eight superconducting accelerating cavities were stably operated under a high beam current and a large beam induced HOM power in KEKB electron ring. The HOM power of 16 kW at the beam current of 1.4A was absorbed in two ferrite dampers attached to each cavity. In SuperKEKB, that is the upgrade machine of KEKB, the design beam current is 2.60 A. The HOM power of higher than 40 kW is expected to be induced. To cope with the large HOM power, precise evaluations of HOM power loads including HOM dampers were carried out. Then, new ferrite dampers with reinforced water cooling were developed and high-power tested. On the other hand, the evaluation indicated that an additional HOM damper can absorb significant amount of HOM power. Additional damper is effective to reduce each ferrite damper load. In this report, we will describe the results of high power tests of the new ferrite dampers, studies for additional dampers, and an installation plan for SuperKEKB.

THP062	Optimisation of the 3-Stub Tuner for Matching the Diamond SCRF Cavities	cavity, simulation, coupling, storage-ring	1061
	S.A. Pande, C. Christou, P. Gu, M. Jensen Diamond, Oxfordshire, United Kingdom
	The Diamond Storage Ring cavities are aperture coupled resulting in a fixed external Q. This results in the cavities being matched under certain conditions depending on the loss per turn, the beam current and the accelerating voltage. Operationally, there are advantages to limiting the accelerating voltage to improve reliability and lifetime, which at high beam current results in a mismatch and high reflected power. To match the cavities under such non-optimum operating conditions we use 3-stub tuners in the waveguide feeds. It has been observed, that certain configurations of the 3-stub tuners can improve the match of the cavity, but this can result in strong heating of the waveguide in the cryostat. Numerical simulations of the cavity along with the coupling waveguide and 3-stub tuners have been carried out using CST Studio for different beam loading conditions to optimise the 3-stub tuners for acceptable match and heating. In this paper we present the results of our simulations and comparisons with measurements for operation with different beam currents and cavity voltages.

THP065	Design of 352.21 MHz RF Power Input Coupler and Window for the European Spallation Source Project (ESS)	cavity, multipactoring, vacuum, SRF	1069
	E. Rampnoux, S. Bousson, S. Brault, P. Duchesne, P. Duthil, G. Olry, D. Reynet IPN, Orsay, France
	A 352.21 MHz RF high power coupler window was designed by IPNO to meet the specification requirements for the ESS accelerator project. This designed is based on IPNO’s power coupler developments performed in the framework of the EURISOL Design Study project for which two power couplers using coaxial technology without chokes systems around the ceramic disc have been designed and tested successfully up to 20 kW RF power level in CW mode. For ESS project, the RF power input window was developed and designed to reliability operate at an average power level of 25 kW up to 300 kW in pulsed and continuous wave modes. This 352.21 MHz RF window was developed to remove the chocks usually used and provided the following advantages: more reliability, less expensive to manufacture, better vacuum, easier cleaning, less secondary electron-multipacting with specificity to present a bandwidth close to 1 GHz.

THP066	SARAF Phase-I HWR Coupler Cooling Design	simulation, linac, cavity, proton	1073
	J. Rodnizki, Y. Ben Aliz, I. Fishman, A. Grin, Z. Horvitz, B. Kaizer, L. Weissman Soreq NRC, Yavne, Israel
	The Soreq Applied Research Accelerator Facility (SARAF) design is based on a 40 MeV 5 mA light ions superconducting RF linac. Phase I of SARAF delivers up to 2 mA CW proton beam in an energy range of 1.5-4.5 MeV. The maximum beam power that we have reached is 4.5 kW. The warming of the SARAF linac RF couplers is currently the main limiting factor for reaching higher CW beam power. The coupler cooling configuration was optimized by increasing the cold window copper braid and adding a copper braid to the top end, using CST Multiphysics and ANSYS steady state and transient solvers. The study was conducted for the heat load generated by the surface currents of a matched 4 kW forward CW power, simulated by the CST MWS FD solver. Multipacting is a known potential heat source that overheats the coupler in the vicinity of the cold window. The coupler overheat phenomena was experimentally studied as a function of DC bias voltage, and it was found that a 900 V bias reduces significantly the heating rate. As a result we expect that the beam power can be significantly increased. The long overheat period implies that optimization of the cooling configuration is still needed.

THP068	New Design of HOM Coupler Using Coaxial-like Rounded Waveguide	HOM, cavity, damping, simulation	1081
	M. Sawamura Japan Atomic Energy Agency (JAEA), Gamma-ray Non-Destructive Assay Research Group, Tokai-mura, Ibaraki-ken, Japan R. Hajima, R. Nagai, N. Nishimori JAEA, Ibaraki-ken, Japan
	It is important to damp higher-order modes (HOMs) of superconducting accelerators especially for energy-recovery linacs of high current operation. Though various types of HOM couplers, beam line HOM dampers and waveguide HOM couplers have been developed, there are some problems such as inner conductor heating of output connector for HOM couplers and low packing factor for beam line HOM dampers. We propose new design of HOM coupler. This coupler consists of a coaxial line coupled with a cavity or a beam pipe and a rounded waveguide which cuts off the accelerating mode. The rounded waveguide is similar to a coaxial line and the inner conductor and outer conductor are connected with a plate which corresponds to waveguide side wall. This enables the inner connector cooled down efficiently through the outer conductor. The calculation results of MW-STUDIO will be presented.

THP072	Input Coupler for Cornell ERL Main Linac	linac, cavity, cryomodule, vacuum	1094
	V. Veshcherevich, P. Quigley Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work is supported by the National Science Foundation grant DMR-0807731. Each cavity of the Cornell ERL Main Linac has a single coaxial type input coupler with fixed coupling, Qext = 6.5×E7. The input coupler will operate at RF power up to 5 kW at full reflection. The coupler design is based on the design of TTF-III input coupler with appropriate modifications and with taking into account the Cornell experience with couplers for ERL Injector. Seven couplers have been fabricated by CPI, Beverly and tested at Cornell on the test stand up to 5 kW CW. No major issues were noticed during the test. One coupler was attached to the prototype linac cavity. The cavity was successfully tested with great results achieved inside the horizontal test cryomodule. Six other couplers will be installed in the Main Linac Cryomodule (MLC) Prototype.

THP077	Coaxial Blade Tuner for European XFEL 3.9 GHz cavities	cavity, linac, simulation, cryomodule	1101
	R. Paparella, M. Bertucci, A. Bosotti INFN/LASA, Segrate (MI), Italy C. Pagani Università degli Studi di Milano & INFN, Segrate, Italy
	The European XFEL linac injector features a third harmonic section jointly realized by INFN and DESY and hosting a 3.9 GHz 9-cell cavities cryomodule. The cold tuning system, developed by INFN for these cavities, is inspired by the coaxial Blade Tuner already qualified for ILC cavities. Design, fabrication and room temperature qualification of first tuner units produced are reviewed in this paper.

THP078	Deformation Tuner Design for a Double Spoke Cavity	cavity, cryomodule, SRF, linac	1104
	N. Gandolfo, S. Bousson, S. Brault, P. Duchesne, P. Duthil, G. Olry, D. Reynet IPN, Orsay, France
	IPN Orsay is developing the low-beta double Spoke cavities cryomodule for the ESS. Based on previous successfully tested prototypes, a fast/slow tuner has been studied to compensate resonance frequency variations of the cavity during operation. The typical perturbations are coming from LHe pressure variations as well as microphonics and Lorentz force detuning (LFD). Two tuners are being built in order to validate both expected performances and series production feasibility. In this paper, the tuner design of the double Spoke cavity is presented.

THP080	SRF Cavity Tuning for Low Beam Loading	cavity, resonance, cryomodule, vacuum	1110
	N. Solyak, E. Borissov, I.V. Gonin, C.J. Grimm, T.N. Khabiboulline, R.V. Pilipenko, Y.M. Pischalnikov, W. Schappert, V.P. Yakovlev Fermilab, Batavia, USA
	The design of 5-cell elliptical 650 MHz β=0.9 cavities to accelerate H⁻ beam of 1 mA average current in the range 467-3000 MeV for the Project X Linac is currently under development at Fermilab. The low beam current enables cavities to operate with high loaded Q’s and low bandwidth, making them very sensitive to microphonics. Mechanical vibrations and the Lorentz force can drive cavities off resonance during operation; therefore the proper design of the tuning system is very important part of cavity mechanical design. In this paper we review the design, performance, operation, reliability and cost of fast and slow tuners for 1.3 GHz elliptical cavities. We also present a design of the slow and fast tuners for 650 MHz β=0.9 cavities based on this experience. The HV in the new design is equipped with the tuners located at the end of the cavity instead of the initially proposed blade tuner located in the middle. We will present the results of ANSYS analyses of mechanical properties of tuners.

THP086	LLRF System Design and Performance for XFEL Cryomodules Continuous Wave Operation	cavity, feedback, LLRF, cryomodule	1129
	J. Branlard, V. Ayvazyan, L. Butkowski, K.P. Przygoda, H. Schlarb, J.K. Sekutowicz DESY, Hamburg, Germany W. Cichalewski, A. Piotrowski TUL-DMCS, Łódź, Poland W. Jałmużna Embedded Integrated Control Systems GmbH, Hamburg, Germany J. Szewiński NCBJ, Świerk/Otwock, Poland
	The Cryomodule Test Bench (CMTB) at DESY is equipped with a 100 kW Inductive Output Tube (IOT) allowing the test of superconducting cryomodules in continuous wave (CW) operation mode. Although significantly different from the nominal pulsed operation mode of the European X-Ray Free Electron Laser (XFEL), CW operation can be handled by the same Low-level Radio Frequency (LLRF) system, within minor firmware modifications. The hardware details of the LLRF setup at CMTB, the firmware and software architecture and performance results from the last CW test are presented in this contribution.

THP087	LLRF Tests of XFEL Cryomodules at AMTF: First Experimental Results	cavity, cryomodule, LLRF, resonance	1132
	J. Branlard, V. Ayvazyan, M.K. Grecki, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany W. Cichalewski, K. Gnidzińska, A. Piotrowski, K.P. Przygoda TUL-DMCS, Łódź, Poland W. Jałmużna Embedded Integrated Control Systems GmbH, Hamburg, Germany
	In preparation for the series production of cryomodules for the European X-ray Free Electron Laser (XFEL), three pre-series cryomodules and several prototypes have been produced and tested at the Cryomodule Test Bench (CMTB) and at the Accelerating Module Test Facility (AMTF) in DESY. Among the numerous tests performed on the modules, the low-level radio frequency (LLRF) tests aim at characterizing the performance of the modules from an RF controls perspective. These integration tests must take into account cavity tuners, cavity motorized couplers, quench gradients, microphonics, piezo control and the overall gradient performance of the cryomodule under test. In this paper, the LLRF-specific tests are summarized and the first experimental results obtained at CMTB and AMTF are presented.

THP096	Recent Upgrade of Ultra-Broadband RF System for Cavity Characterization	cavity, controls, software, pick-up	1151
	S. Stark, V. Palmieri, A.M. Porcellato, A.A. Rossi INFN/LNL, Legnaro (PD), Italy V. Palmieri Univ. degli Studi di Padova, Padova, Italy
	The first computer controlled RF system for SC cavity characterization entered into operation at INFN-LNL in 1994. Since then it has been successfully used for testing SC cavities of different shapes and frequencies. Recently we performed an important upgrade on it in order to cover a wider frequency range and to take advantage of the better performance of nowadays electronic devices. The paper describes the present system layout, dedicated software, sequences of calibration and testing procedures and moreover discusses further upgrading possibilities.

FRIOA01	LHC Crab Cavity .Progress and Outlook	cavity, luminosity, cryomodule, dipole	1161
	R. Calaga, E. Jensen CERN, Geneva, Switzerland
	Three novel superconducting RF crab cavity designs proposed for the LHC luminosity upgrade have rapidly progressed. First Niobium prototypes are reaching close to the design performance and beyond. The highlights of the RF test results from the prototypes along with design modifications for initial beam tests in the SPS are presented. The status of the cryomodule development, integration into the SPS and the beam tests in view of validating the crab cavity system for LHC upgrade are addressed.
	Slides FRIOA01 [12.063 MB]

FRIOA03	Fabrication and Testing of Deflecting Cavities for APS	cavity, coupling, niobium, SRF	1170
	J.D. Mammosser JLab, Newport News, Virginia, USA P. Dhakal, J. Henry, R.A. Rimmer, H. Wang, K.M. Wilson JLAB, Newport News, Virginia, USA J.F. Fuerst, J.P. Holzbauer, J.S. Kerby, A. Nassiri, G.J. Waldschmidt, G. Wu, Y. Yang ANL, Argonne, USA F. He PKU, Beijing, People's Republic of China Z. Li SLAC, Menlo Park, California, USA
	Abstract Jefferson Lab in Newport News, Virginia, in collaboration with Argonne National Laboratory, Argonne, Il, has fabricated and tested three production, 2.815 GHz crab cavities for Argonne’s Short-Pulse X-ray project. These cavities are unique in that the cavity and waveguides were milled from bulk large grain niobium ingot material directly from 3D CAD files. No forming of sub components was used with the exception of the beam-pipes. The cavity and helium vessel design along with the RF performance requirements makes this project extremely challenging for fabrication. Production challenges and fabrication techniques as well as testing results will be discussed in this paper.
	Slides FRIOA03 [22.677 MB]

FRIOB02	Development and Performance of 325 MHz Single Spoke Resonators for Project X	cavity, vacuum, niobium, electron	1187
	L. Ristori, M.H. Awida, P. Berrutti, C.M. Ginsburg, I.V. Gonin, T.N. Khabiboulline, M. Merio, T.H. Nicol, D. Passarelli, A.M. Rowe, D.A. Sergatskov, A.I. Sukhanov, V.P. Yakovlev Fermilab, Batavia, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy. Two types of single spoke resonators will be utilized for beam-acceleration in the low energy part of the Project X linac. SSR1 and SSR2 operate at 325 MHz and at an optimal beta of 0.22 and 0.51 respectively. After the initial phase of prototyping, a production run of 10 SSR1 resonators was recently completed in US industry. The qualification of this group of resonators in the Fermilab VTS is proceeding successfully and nearly complete. The first qualified resonator has been outfitted with a Stainless Steel helium vessel. Preliminary test results for the first jacketed SSR1 are presented. The first RF power couplers were ordered, the design of the double-lever tuning mechanism is almost complete.
	Slides FRIOB02 [8.800 MB]

FRIOB04	CERN Developments for 704 MHz Superconducting Cavities	cavity, niobium, linac, proton	1198
	O. Capatina, G. Arnau-Izquierdo, S. Atieh, I. Aviles Santillana, R. Bonomi, S. Calatroni, J.K. Chambrillon, R. Garoby, F. Gerigk, M. Guinchard, T. Junginger, M. Malabaila, L. Marques Antunes Ferreira, S. Mikulas, V. Parma, T. Renaglia, K.M. Schirm, T. Tardy, M. Therasse, A. Vacca, N. Valverde Alonso, A. Vande Craen CERN, Geneva, Switzerland F. Pillon Kraftanlagen Nukleartechnik GmbH, Heidelberg, Germany
	The Superconducting Proton Linac (SPL) is an R&D effort coordinated by CERN in partnership with other international laboratories. It is aiming at developing key technologies for the construction of a multi-megawatt proton linac based on state-of-the-art RF superconducting technology, which would serve as a driver in new physics facilities for neutrinos and/or Radioactive Ion Beam (RIB). Amongst the main objectives of this R&D effort, is the development of 704 MHz bulk niobium β=1 elliptical cavities, operating at 2 K with a maximum accelerating gradient of 25 MV/m, and the testing of a string of cavities integrated in a machine-type cryomodule. The cavity together with its helium tank had to be carefully designed in coherence with the innovative design of the cryomodule. New fabrication methods have also been explored. Five such niobium cavities and two copper cavities are in fabrication. The key design aspects are discussed, the results of the alternative fabrication methods presented and the status of the cavity manufacturing and surface preparation is detailed.
	Slides FRIOB04 [8.677 MB]

FRIOC01	Design of the 352 MHz, Beta 0.50, Double-Spoke Cavity for ESS	cavity, cryomodule, simulation, niobium	1212
	P. Duchesne, S. Bousson, S. Brault, P. Duthil, G. Olry, D. Reynet IPN, Orsay, France S. Molloy ESS, Lund, Sweden
	The ESS proton accelerator contains a superconducting sector consisting in three families of superconducting radiofrequency (SRF) bulk niobium cavities, operating at a nominal temperature of 2K: a family of Spoke cavities for the medium energy section followed by two families of elliptical cavities for higher energies. The superconducting Spoke section, having a length of 58.6m, consists of 14 cryomodules, each of them housing two 352.2 MHz β=0.50 Double-Spoke Resonators (DSR). The operating accelerating field is 8MV/m. The choice of the Spoke technology is guided by the high performances of such structures. Benefitting from 10 years of extensive R&D experience carried out at IPNO, the electromagnetic design studies came out with a solution that fulfills requirements of beam dynamics analysis and manufacturing considerations. Pursuing the same objective, the mechanical design of the cavity and its helium vessel were optimized by performing intensive coupled RF-mechanical simulations. We propose to present a review of the RF and mechanical design studies of the Spoke cavity. We will conclude with the integration of the Spoke cavity with its ancillaries inside the cryomodule.
	Slides FRIOC01 [6.321 MB]

Paper

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MOIOA01

The FRIB Project at MSU

cavity, cryomodule, linac, ion

1

M. Leitner, B. Bird, F. Casagrande, S. Chouhan, C. Compton, J.L. Crisp, K. Elliott, A. Facco, A.D. Fox, M. Hodek, M.J. Johnson, G. Kiupel, I.M. Malloch, D. Miller, S.J. Miller, D. Morris, D. Norton, R. Oweiss, J.P. Ozelis, J. Popielarski, L. Popielarski, A.P. Rauch, R.J. Rose, K. Saito, M. Shuptar, N.R. Usher, G.J. Velianoff, D.R. Victory, J. Wei, J. Whitaker, K. Witgen, T. Xu, Y. Xu, O. Yair, S. Zhao
FRIB, East Lansing, USA

Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
The Facility for Rare Isotope Beams (FRIB) is ready to start construction. The facility will utilize a high-intensity, heavy-ion driver linac to provide stable ion beams from protons to uranium up to energies of >200 MeV/u and at a beam power of up to 400 kW. The superconducting cw linac consists of 330 individual low-beta (β = 0.041, 0.085, 0.29, and 0.53 at 80.5 MHz and 322 MHz) cavities in 49 cryomodules operating at 2 K. This paper discusses the current development status of the project with emphasis on the linac SRF acquisition. SRF coldmass and cryomodule component designs are briefly summarized. A SRF production facility, currently under construction, is described.

Slides MOIOA01 [9.804 MB]

MOIOA04

SRF Challenges for Energy Recovery Linacs

cavity, SRF, HOM, linac

24

A. Burrill
HZB, Berlin, Germany

Many of the challenges associated with operating a SRF ERL are independent of the choice of operating frequency, beam energy, and overall purpose of the machine. Worldwide there are an increasing number of ERLs in various stages of development and operation which are facing a number of similar challenges and often solving them in very different ways. In this talk I will seek to summarize the main challenges the community as a whole faces, address how different laboratories are working to solve these problems, and seek to identify areas of overlap where the community can work together to solve some of these common problems.

Slides MOIOA04 [5.213 MB]

MOIOB01

High Power Proton/Deuteron Accelerators

linac, SRF, proton, cavity

35

J.-L. Biarrotte
IPN, Orsay, France

High power proton and deuteron linear accelerators can give rise to a large variety of scientific applications, useful for both fundamental and applied research. Thanks to the on-going efficient development of the superconducting RF technology, more and more projects based on such machines have emerged during the last 2 decades. This paper will review these existing high power proton/deuteron accelerator facilities or projects, trying in particular to emphasize in each case the various specificities and challenges related to the SRF technology.

Slides MOIOB01 [4.474 MB]

MOIOC01

Heat Transfer at the Interface Between Niobium and Liquid Helium for 6 GHz SRF Cavities

cavity, niobium, interface, coupling

57

V. Palmieri
INFN/LNL, Legnaro (PD), Italy

Cavity Thermal Boundary Resistance is something extremely complex and not completely understood by the theory. Often identified with the Kapitza resistance or with the Khalatnikov acoustic phonon mismatch at the interface metal-liquid Helium, it depends on so many different and uncontrolled parameters, that its interpretation is not covered by a complete treatise of the phenomenon. Therefore, 99% of the literature on superconducting cavities worries about the cavity interior surface state,while almost nothing is reported on treatments applied to the exterior. In the authors opinion, there is a lack in experimental data analysis due to the fact that the cavity is often considered as a whole adiabatic entity interacting only with RF fields. On the contrary, the cavity is immersed in liquid Helium and the cavity behavior cannot prescind from its thermal properties. Indeed in the normal state He-I has poor thermal conductivity and high specific heat. Moreover the heat exchange at HeII obeys to further mechanisms besides the phonon mismatch. Driven by the hypothesis that thermal losses are dominant for ultraclean cavities, we have collected a plethora of surprising experimental results.

Slides MOIOC01 [15.558 MB]

MOP003

Implications of Increased Beam Current for the Diamond Storage Ring RF System

cavity, storage-ring, cathode, linac

73

C. Christou, A. Bogusz, P. Gu, M. Maddock, P.J. Marten, S.A. Pande, A.F. Rankin, D. Spink, A.V. Watkins
Diamond, Oxfordshire, United Kingdom

Diamond Light Source presently operates for users with 300mA beam current and initial tests have begun to upgrade this current towards an ultimate goal of 500mA. The implications of such a beam current increase for the storage ring RF system will be significant, including the installation of a third superconducting cavity and a possible modification of the coupling parameters of the existing cavities. An overview of the planned enhancements of the RF system is presented, including an update of the procurement of a new CESR-design cavity and options for installation and operation of this cavity and supporting infrastructure.

MOP007

The Status of Superconducting Linac and SRF Activities at the SNS

linac, cryomodule, cavity, SRF

83

S.-H. Kim, W. Blokland, M.S. Champion, A. Coleman, M.T. Crofford, M. Doleans, D.L. Douglas, T.V. Gorlov, M.P. Howell, Y.W. Kang, A.P. Shishlo, S.E. Stewart, W.H. Strong
ORNL, Oak Ridge, Tennessee, USA
R. Afanador, B. DeGraff, B.S. Hannah, S.W. Lee, C.J. McMahan, T.S. Neustadt, S.W. Ottaway, C.C. Peters, J. Saunders, D.M. Vandygriff
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
There have been substantial gains at the Spallation Neutron Source (SNS) in last 7 years in understanding pulsed superconducting linac (SCL) operation including system and equipment limiting factors and resolution of system and equipment issues. Significant effort and focus are required to assure ongoing success of the operation, maintenance and improvement of the SCL, and to address the requirements of the upgrade project in the future. The SNS is taking a multi-faceted approach to maintaining and improving its linac. A balanced set of facilities which support processing, assembly, repair, and testing of cavities/cryomodules are currently being placed into service. This paper summarizes the status of the SNS SCL and related superconducting radio-frequency (SRF) activities such as development of ASME code-stamped spare cryomodules, R&D activities for SRF cavity performance improvements, SRF cavity development for power upgrade project and SRF facility development/upgrade to support all required activities.

MOP010

Spiral2 Cryomodules B Tests Results

cryomodule, cavity, linac, alignment

95

G. Olry, F. Chatelet, C. Commeaux, N. Gandolfo, D. Grolet, C. Joly, J. Lesrel, D. Longuevergne, R. Martret, G. Michel, L. Renard, A. Stephen, P. Szott
IPN, Orsay, France
P.-E. Bernaudin, R. Beunard, R. Ferdinand, A. Lefevre
GANIL, Caen, France
Y. Gómez Martínez
LPSC, Grenoble Cedex, France

Assembly and tests of the SPIRAL2 superconducting linac's cryomodules at CEA/Saclay and IPN/Orsay have now reached cruising speed after having faced a series of problems, among them contamination. 19 cryomodules are composing the whole Linac and IPN Orsay is in charge of the 7 cryomodules B, housing two 88MHz, beta 0.12 Quarter-Wave Resonators. Two cryomodules have been successfully assembled and tested up to the nominal gradient of 6.5 MV/m for all cavities with also total cryogenic losses under specifications. One of them is fully qualified and has been already delivered to GANIL. The second one showed misalignment on one cavity which could lead to partial disassembly. This paper will present the results of those cryomodules tests as well as the status of the remaining ones.

MOP012

Completion of the Superconducting Heavy Ion Linac at Inter-University Accelerator Centre

linac, electronics, ion, controls

103

A. Rai, R. Ahuja, J. Antony, S. Babu, J. Chacko, G.K. Chaudhari, A. Chaudhary, T.S. Datta, R.N. Dutt, S. Ghosh, R. Joshi, D. Kanjilal, S. Kar, J. Karmakar, M. Kumar, R. Kumar, D.S. Mathuria, R. Mehta, K.K. Mistri, A. Pandey, P. Patra, P.N. Prakash, A. Roy, J. Sacharias, B.K. Sahu, A. Sarkar, S.S.K. Sonti, S. K. Suman, J. Zacharias
IUAC, New Delhi, India

The Superconducting heavy ion Linac at Inter University Accelerator Centre (IUAC), New Delhi has been delivering accelerated ion beams to the users since 2009 *. Initially the first accelerating module, housing eight Quarter Wave Resonators (QWR’s), became operational together with the Superbuncher having one and the Rebuncher having two QWR’s, respectively. In the subsequent years, the remaining two modules have been installed and commissioned. The complete Linac was operated recently and several ion beams were delivered for scheduled experiments. The maximum energy gain was 8 MeV per charge state. Operational highlights include successful operation of four resonators in the third module with Piezo based ** mechanical tuning, implementation of remote phase locking for all resonators in three modules, development of a scheme for auto locking of resonators and testing of a capacitive pickup as a beam diagnostic element. Details will be presented vis-à-vis the problems encountered and the future course of action.
* A. Rai et. al., Proc. of SRF2009 Sept. 20–25, 2009, Berlin, Germany, page 244.
** B.K.Sahu et. al., Proc. of IPAC 2010, Kyoto Japan, page 2920.

MOP013

SRF Developments at MSU for FRIB

solenoid, cavity, shielding, cryomodule

106

K. Saito, N.K. Bultman, F. Casagrande, S. Chouhan, C. Compton, K. Elliott, A. Facco, M.J. Johnson, S. Jones, M. Leitner, S.J. Miller, R. Oweiss, J.P. Ozelis, J. Popielarski, L. Popielarski, S. Shanab, J. Wei, T. Xu, Y. Yamazaki, Y. Zhang, Z. Zheng
FRIB, East Lansing, Michigan, USA
S.K. Chandrasekaran
MSU, East Lansing, USA
K. Hosoyama
KEK, Ibaraki, Japan

FRIB has built up a new SRF development group for future SRF research and development at MSU. This paper will report on the present status of development for fundamental couplers, pneumatic tuners for HWR, magnetic shielding and superconducting solenoids, barrel polishing techniques for HWR, a cavity steam cleaning method, and niobium material characterization efforts.

MOP018

Design of the MYRRHA 17-600 MeV Superconducting Linac

linac, cavity, lattice, simulation

129

J.-L. Biarrotte
IPN, Orsay, France
F. Bouly
CERN, Geneva, Switzerland
J.-P. Carneiro
Fermilab, Batavia, USA
D. Uriot
CEA/DSM/IRFU, France
D. Vandeplassche
SCK•CEN, Mol, Belgium

Funding: This work is being supported by the European Atomic Energy Community’s (EURATOM) Seventh Framework Programme under grant agreement n°269565 (MAX project).
The goal of the MYRRHA project is to demonstrate the technical feasibility of transmutation in a 100MWth Accelerator Driven System (ADS) by building a new flexible irradiation complex in Mol (Belgium). The MYRRHA facility requires a 600 MeV accelerator delivering a maximum proton flux of 4 mA in continuous operation, with an additional requirement for exceptional reliability. This paper will briefly describe the beam dynamics design of the main superconducting linac section which covers the 17 to 600 MeV energy range and requires enhanced fault-tolerance capabilities.

MOP020

Progress of the LUNEX5 Project

FEL, laser, electron, undulator

133

P. Marchand, C. Benabderrahmane, L. Cassinari, M.-E. Couprie, J. Daillant, M. Diop, M.E. El Ajjouri, N. Hubert, M. Labat, R. Lopes, A. Loulergue, M. Louvet, O. Marcouillé, J.L. Marlats, C. Miron, P. Morin, A. Nadji, F. Ribeiro, P. Roy, K. Tavakoli
SOLEIL, Gif-sur-Yvette, France
S. Bielawski, C. Evain, E. Roussel, C. Szwaj
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
B. Carré, D. Garzella
CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France
N. Delerue
LAL, Orsay, France
G. Devanz, M. Luong
CEA/DSM/IRFU, France
A. Dubois, J. Lüning
CCPMR, Paris, France
G. Lambert, R. Lehe, A. Lifschitz, V. Malka, A. Rousse, C. Thaury
LOA, Palaiseau, France

LUNEX5 (free electron Laser Using a New accelerator for the Exploitation of X-ray radiation of 5th generation) aims at investigating the production of short, intense, and coherent pulses in the soft X-ray region. It comprises two types of accelerators connected to a single Free Electron Laser (FEL), enabling the most advanced seeding configurations : High order Harmonic in Gas (HHG) seeding and Echo Enable Harmonic Generation (EEHG) with cryogenic in-vacuum undulators. The 400 MeV Conventional Linear Accelerator (CLA) uses superconducting cavities, compatible with a future upgrade towards high repetition rate for investigating advanced FEL schemes. It will also enable multi-user operation by splitting part of the macropulse to different FEL lines. A 0.4 - 1 GeV Laser Wake Field Accelerator (LWFA) will also be qualified in view of FEL applications, in the single spike or seeded regime. After the Conceptual Design Report, R&D has been launched on a cryo-ready 3 m long in-vacuum undulator, variable strong permanent magnet quadrupoles, Smith-Purcell and electro-optics diagnostics. A test experiment is also under preparation for validating the computed beam transport from the LWFA.

MOP029

Cryo-Losses Measurements of the XFEL Prototype and Pre-Series Cryomodules

cryomodule, cryogenics, electron, linac

162

S. Barbanotti, J. Eschke, K. Jensch, W. Maschmann, O. Sawlanski
DESY, Hamburg, Germany
W. Gaj, L.M. Kolwicz-Chodak, W. Maciocha
IFJ-PAN, Kraków, Poland
X. Wang
ESS, Lund, Sweden

Cryo-losses measurements of the XFEL prototype and pre-series cryomodules are here presented and compared with the XFEL requirements. Cryo-losses at the 4.5 K, 80 K and 2K temperatures are calculated during the test period at CMTB (CryoModule Test Bench) at DESY to qualify the cryomodules before installation. This paper summarizes the test procedure for the different circuits (2K, 4.5K, 80K) and in different load conditions: static losses, losses due to the magnet and dynamic losses due to the RF power sent to the cavities at different MV/m levels.

MOP031

Quality Control of the Vessel and Cold Mass Production for the 1.3 GHz XFEL Cryomodules

vacuum, controls, cryomodule, cavity

168

S. Barbanotti, H. Hintz, K. Jensch, W. Maschmann
DESY, Hamburg, Germany

The industrial production of one hundred cold masses and vacuum vessels for the 1.3 GHz XFEL cryomodules is now fully in operation. Quality checks at the companies and controls at DESY assure the quality level required for the cryomodule assembly. Verification of the main production steps, non-destructive tests, dimensional controls are performed by DESY personnel before accepting the components. This paper resumes the quality control strategy and the results for the first components produced by the companies.

MOP042

Quality Control and Processes Optimization for the EXFEL Superconducting Cavities Series Production at Ettore Zanon spa

cavity, controls, vacuum, SRF

208

L. Facci, D. Rizzetto
Ettore Zanon S.p.A., Nuclear Division, Schio, Italy
G. Corniani
Ettore Zanon S.p.A., Schio, Italy
A. Matheisen
DESY, Hamburg, Germany
P. Michelato, L. Monaco
INFN/LASA, Segrate (MI), Italy

The construction of the European XFEL forced the first mass production of Niobium bulk SRF cavities. In this context Ettore Zanon S.p.A. built a fully new facility designed to produce four fully treated and He tank equipped cavities per week, ready to be tested at DESY. The facility already reached the foreseen production rate. The guarantee of the highest quality of the resonators produced requires a very strict quality control plan. At the same time, the requirements of the industrial production in terms of time, cost and productivity must be satisfied. As a consequence processes must be standardized and working times optimized. In the following, after the description of the production facility, we would like to highlight and discuss the strategies and arrangements adopted in the various critical fields (clean room, vacuum, etc.) to ensure the foreseen results. Moreover correlation between cavities performances and production cycle parameters will be investigated and discussed.

MOP048

PED Requirements Applied to the Cavity and Helium Tank Manufacturing

cavity, niobium, linac, controls

227

A. Schmidt, J. Iversen, A. Matheisen, W. Singer
DESY, Hamburg, Germany

For the European XFEL more than 800 Cavities are manufactured by industrial partners. Each cavity is housed in an individual cryo vessel, the so called helium tank. All vessels are made from titanium and manufactured by industry as well. The cavity, welded into its helium tank, is a pressure loaded part and has to follow the pressure equipment directive - PED (97/23/EC). Setting up a series production of cavities and helium tanks by different vendors according given standards, was the task of the EXFEL WPG-1 LINAC-WP04. In cooperation with the TUEV-Nord as the notified body, DESY is responsible for the qualification of design, material in use and reasonable tests to get a certificate for pressure bearing parts.

MOP054

Tests of the Accelerating Cryomodules for the European X-Ray Free Electron Laser

cryomodule, cryogenics, cavity, radiation

244

M. Wiencek, B. Dzieza, W. Gaj, D. Karolczyk, K. Kasprzak, L.M. Kolwicz-Chodak, A. Kotarba, A. Krawczyk, K. Krzysik, W. Maciocha, A. Marendziak, K. Myalski, S. Myalski, T. Ostrowicz, B. Prochal, M. Sienkiewicz, M. Skiba, J. Świerbleski, J. Zbroja, A. Zwozniak
IFJ-PAN, Kraków, Poland

The European X-ray Free Electron Laser (XFEL) is currently under construction in Germany in Hamburg area. A 2.1 km long superconducting linear accelerator, part of the XFEL, consists of 101 accelerating cryomodules. The XFEL cryomodule is assembled with eight superconducting RF cavities, one cold magnet and Beam Position Monitor (BPM). The cryomodules are tested in dedicated test facility before installation in the XFEL tunnel. The testing procedures for the cryomodules were prepared with use of DESY expertise from TTF (Tesla Test Facility) Collaboration and FLASH (Freie-Elektronen-Laser in Hamburg). This paper describes the full set of testing procedure and incoming and outgoing inspections as well.

MOP061

75 mA Operation of the Cornell ERL Superconducting RF Injector Cryomodule

HOM, SRF, cryomodule, cavity

259

M. Liepe, B.M. Dunham, R.G. Eichhorn, G.H. Hoffstaetter, R.P.K. Kaplan, P. Quigley, E.N. Smith, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work is supported by the National Science Foundation (Grant No. DMR-0807731).
Cornell University has developed a SCRF injector cryomodule for the acceleration of high current, low emittance beams in continuous wave operation. This cryomodule is based on 1.3 GHz superconducting RF technology, and has been tested extensively in the Cornell ERL injector prototype with world record CW beam currents exceeding 70 mA. High CW RF power input couplers and strong Higher-Order-Mode damping in the cavities are essential for high beam current operation. This paper summarizes the performance of the cryomodule during the high beam current operation.

MOP062

Production of 500 MHz SRF Modules the KEKB-type for Taiwan Photon Source

SRF, cavity, niobium, vacuum

263

Ch. Wang, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Y.-H. Lin, Z.K. Liu, C.H. Lo, M.H. Tsai, T.-T. Yang, M.-S. Yeh, T.-C. Yu
NSRRC, Hsinchu, Taiwan
T. Furuya, K. Hara, T. Honma, A. Kabe, Y. Kojima, S. Mitsunobu, Y. Morita, H. Nakai, K. Nakanishi, M. Nishiwaki, S. Takano
KEK, Ibaraki, Japan
F. Inoue, K. Sennyu, T. Yanagisawa
MHI, Hiroshima, Japan

The KEKB-type single-cell 500-MHz superconducting radio frequency (SRF) modules have been selected to power the 3 GeV, 500 mA, storage ring of the constructing Taiwan Photon Source (TPS) at National Synchrotron Radiation Research Center (NSRRC). The design target is to routinely deliver RF forward power up to 300 kW, CW, to single SRF module with highly reliable operation. Three sets of SRF modules have been successfully produced under a tight collaboration with High Energy Accelerator Research Organization (KEK) and Mitsubishi Heavy Industries Ltd. (MHI), after obtaining the technology transfer from KEK. MHI is responsible for the mechanical fabrication and cryo-module assembly, KEK for the surface and RF treatments of the niobium cavities, high power input couplers and HOM dampers and for the liquid-helium tests of the cryo-modules, and NSRRC for the electronic/diagnostic system, final assembly and system integration, high power horizontal test, and reliable test. This work reports the results obtained during the production of these three SRF modules at KEK and NSRRC.

MOP063

Mature Operation of CESR-Type 500-MHz SRF Module at Taiwan Light Source

SRF, vacuum, cavity, cryogenics

266

Ch. Wang, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Y.-H. Lin, Z.K. Liu, C.H. Lo, M.H. Tsai, T.-T. Yang, M.-S. Yeh, T.-C. Yu
NSRRC, Hsinchu, Taiwan

The Cornell-type 500-MHz SRF module has been routinely operated since the end of 2004 to power the 1.5 GeV Taiwan Light Source with 360 mA in top-up mode. A new record of SRF operation with mean time between failures (MTBF)up to 800 hr has been achieved in the 1st half of 2013 that is compatible with the best operational record of room temperature cavities ever made in the same machine. To meet the user’s strict requirements on highly operational reliability, developing in advanced diagnostic instrumentation together with user-friendly event logging software does never stop. Here, we review our SRF operational experience in last 9 years.

MOP064

Operational Experience with the SOLEIL Superconducting RF System

cavity, cryogenics, HOM, vacuum

269

P. Marchand, J.P. Baete, R.C. Cuoq, H.D. Dias, M. Diop, J.L. Labelle, R. Lopes, M. Louvet, C.M. Monnot, S. Petit, F. Ribeiro, T. Ruan, R. Sreedharan, K. Tavakoli
SOLEIL, Gif-sur-Yvette, France

In the SOLEIL storage ring, two cryomodules provide to the electron beam an accelerating voltage of 3-4 MV and a power of 575 kW at 352 MHz. Each cryomodule contains a pair of superconducting cavities, cooled with liquid Helium at 4K, which is supplied by a single 350 W cryogenic plant. The RF power is provided by 4 solid state amplifiers, each delivering up to 180 kW. The parasitic impedances of the high order modes are strongly mitigated by means of four coaxial couplers, located on the central pipe connecting the two cavities. Seven years of operational experience with this system as well as its upgrades are reported.

MOP070

Results on Quality Factors of 1.3 GHz Nine-Cell Cavities at DESY

cavity, factory, niobium, linear-collider

297

F. Schlander
IKP, Mainz, Germany
F. Schlander
DESY, Hamburg, Germany

Superconducting cavities made of niobium are the basis of many particle accelerators around the world. Besides the quest for high accelerating fields for projects like European XFEL and the International Linear Collider, the quality factor, a measure for the resistance and hence the ohmic losses, is of importance, as it eventually determines the cryoplant size and its costs of operation. Especially for accelerators operating in continuous wave mode, the dynamic heat load generated by cavity operation exceeds the static heat load by far and thus requires minimisation. To investigate the current quality factor performance of 1.3 GHz cavities at DESY, the test results of some 50 recent cavities with state-of-the-art treatment have been examined regarding surface treatment and material.

Slides MOP070 [0.590 MB]

MOP078

Horizontal Testing of a Dressed Deflecting Mode Cavity for the APS Upgrade Short Pulse X-Ray Project

cavity, controls, photon, vacuum

321

J.P. Holzbauer, N.D. Arnold, T.G. Berenc, D.J. Bromberek, J. Carwardine, N.P. Di Monte, J.D. Fuerst, A.E. Grelick, D. Horan, J.A. Kaluzny, J.W. Lang, H. Ma, T.L. Mann, D.A. Meyer, M.E. Middendorf, A. Nassiri, Y. Shiroyanagi, J.H. Vacca, G.J. Waldschmidt, R.D. Wright, G. Wu, Y. Yang, A. Zholents
ANL, Argonne, USA
E.R. Harms, W. Schappert
Fermilab, Batavia, USA
J.D. Mammosser
JLAB, Newport News, Virginia, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CHI1357.
The short pulse x-ray (SPX) part of the Advanced Photon Source (APS) Upgrade is an effort to enhance time-resolved experiments on a few-ps-scale at the APS. The goal of SPX is the generation of short pulses of x-rays for pump-probe time-resolved capability using superconducting rf (SRF) deflecting cavities*. These cavities will create a correlation between longitudinal position in the electron bunch and vertical momentum**. The light produced by this bunch can be passed through a slit to produce a pulse of light much shorter (1-2 ps instead of 100 ps) than the bunch length at reduced flux. An SPX cavity has been tested with a helium vessel and tuner. In addition to studying rf performance with more realistic cooling, this test allowed integration and operation of many systems designed for SPX cryomodule in-ring operation. These systems included an APS-constructed 5 kW, 2.815 GHz amplifier, a digital low-level rf controller system designed and fabricated in collaboration with LBNL, a cavity tuner, and instrumentation systems designed for the existing APS infrastructure. Cavity performance and subsystem performance will be reported and discussed in this paper.
* A. Zholents et al., NIM A 425, 385 (1999).
** A. Nassiri et al., “Status of the Short-Pulse X-Ray Project at the Advanced Photon Source,” IPAC 2012, New Orleans, LA, May 2012.

MOP080

Design of a New Horizontal Test Cryostat for SCRF Cavities at the Uppsala University

cavity, cryomodule, radiation, vacuum

328

T. Junquera, P. Bujard, N.R. Chevalier, J.P. Thermeau
Accelerators and Cryogenic Systems, Orsay, France
L. Hermansson, M. Noor, R.J.M.Y. Ruber, R. Santiago Kern
Uppsala University, Uppsala, Sweden
H. Saugnac
IPN, Orsay, France

At Uppsala University, the FREIA facility for research and development of new accelerators and associated instrumentation, is presently in construction. Associated to a new Helium Liquefier, a Horizontal Test Cryostat will be used for high power RF tests of completely equipped SC cavities. This paper presents the main characteristics of the cryostat and the associated cryogenic distribution system. Two types of cavities have been considered for test purpose: SC elliptical cavities for future free electron lasers and SC cavities for high intensity proton accelerators (i.e. SC spokes). A special valve box including a subcooling stage and power coupler cooling with supercritical Helium supply have been designed, for temperature operation ranging from 2K to 4.2 K. This facility will play an essential role in the development and test of cavities, couplers and cryomodules for the ESS project. High power RF sources will be installed in order to allow unique and complete tests of spoke cavities and cryomodules at high nominal peak power.

MOP081

Preliminary Studies of the Cryogenic Refrigerator and Distribution Systems for the MYRRHA Proton Linac

cryogenics, linac, cryomodule, proton

331

T. Junquera, N.R. Chevalier, J.P. Thermeau
Accelerators and Cryogenic Systems, Orsay, France
L. Medeiros Romão, D. Vandeplassche
SCK•CEN, Mol, Belgium
H. Saugnac
IPN, Orsay, France

Funding: Work supported by the EU, FP7 MAX contract number 269565
In the framework of recent European programs (FP6-Eurotrans, FP7-MAX), the SC proton Linac for the MYRRHA project (associating an accelerator to a subcritical nuclear reactor, to be installed in the SCK•CEN at Mol-Belgium), has been extensively studied and optimized to reach strict requirements in beam power and reliability as needed for this ADS demonstrator. The linac, composed of 150 SC cavities (CH, spoke and elliptical) installed in 60 cryomodules, operates at 2K, delivering a beam power of 2.5 MW (600 MeV, 4 mA) in CW mode, will be installed in a tunnel of 240 m length. In this paper we present the evaluation of the cryogenic power requirements, a preliminary architecture of the cryogenic refrigerator system including all its major components, and preliminary proposals for the cryofluids distribution along the SC linac.

MOP082

Development and Test of a New Cryostat Module for the Injector of the S-DALINAC*

electron, vacuum, cavity, linac

334

T. Kürzeder, J. Conrad, F. Hug, N. Pietralla, A. Richter, S.T. Sievers
TU Darmstadt, Darmstadt, Germany
R.G. Eichhorn
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: *This work is supported by the DFG through the Collaborative Research Center SFB 634.
The present injector of the superconducting Darmstadt electron linear accelerator S-DALINAC provides an electron beam of up to 10 MeV kinetic energy and up to 60 μA current in continuous wave operation. A new cryostat module has been constructed to replace the actual one in order to provide higher beam energies of up to 14 MeV and currents of up to 250 μA for nuclear resonance fluorescence experiments at the Darmstadt High Intensity Photon Setup (DHIPS). As before two 20-cell superconducting microwave cavities will be operated at an acceleration frequency of 3 GHz in a liquid helium bath at 2 K. For the injector upgrade two new elliptical 20-cell niobium cavities were also manufactured and in addition a third spare one. The rf power is transferred to the cavities by an also newly developed waveguide-transition line and input couplers. We report on the construction of the cryostat module and its components and present the results of a first cooling-down procedure.

MOP083

Operational Experience With the SOLEIL Storage Ring RF Cryogenic Plant

cryogenics, controls, cavity, HOM

337

M. Louvet, H.D. Dias, M. Diop, P. Marchand
SOLEIL, Gif-sur-Yvette, France

In the Storage Ring of the Synchrotron SOLEIL light source, two cryomodules provide the required power of 575 kW at the nominal energy of 2.75 GeV with the full beam current of 500 mA and all the insertion devices. Each cryomodule contains a pair of 352 MHz superconducting cavities (Nb/Cu), cooled in a bath of liquid helium at 4.5 K. A single 350 W cryogenic system supplies the liquid helium for the two cryomodules. The seven years of operational experience with this cryogenic plant as well as its upgrades are reported.

MOP084

ESS Cryomodules for Elliptical Cavities

cryomodule, vacuum, cryogenics, cavity

341

G. Olivier, J.P. Thermeau
IPN, Orsay, France
P. Bosland
CEA/IRFU, Gif-sur-Yvette, France
C. Darve
ESS, Lund, Sweden

The European Spallation Source will be the world's most powerfull neutron source. IPN Orsay undertakes the development of the ESS linac cryomodules for both medium and high beta elliptical cavities which constitute the high energy section. A medium beta technical demonstrator will be built in a first time. The cryomodules are composed of 4 superconducting cavities cooled at 2K. The cold mass assembly is hanged in an intermediate structure located inside the vacuum vessel. A 50K fixed temperature is implemented by the mean of an aluminium shield. Each cryomodule is connected to the cryogenic distribution line. The vacuum vessel is 6.3m long and has a 1.2m diameter. The poster describes the general design,the solutions implemented, the characteristics of the main components and the mechanical/thermal calculations .

MOP085

Status of the Superconducting Proton Linac (SPL) Cryomodule

cavity, vacuum, cryogenics, linac

345

V. Parma, R. Bonomi, O. Capatina, J.K. Chambrillon, E. Montesinos, K.M. Schirm, A. Vande Craen, G. Vandoni, R. van Weelderen
CERN, Geneva, Switzerland
G. Devanz
CEA/IRFU, Gif-sur-Yvette, France
P. Duchesne, P. Duthil, S. Rousselot
IPN, Orsay, France

The Superconducting Proton Linac (SPL) is an R&D effort conducted by CERN in partnership with other international laboratories, aimed at developing key technologies for the construction of a multi-megawatt proton linac based on state-of-the-art SRF technology. Such an accelerator would serve as a driver in new physics facilities for neutrinos and/or radioactive ion beams. Amongst the main objectives of this effort, are the development of 704 MHz bulk niobium β=1 elliptical cavities (operating at 2 K and providing an accelerating field of 25 MV/m) and the test of a string of cavities integrated in a machine-type cryo-module. In an initial phase, only four out of the eight cavities of the SPL cryo-module will be tested in a half- length cryo-module developed for this purpose, which nonetheless preserves the main features of the full size machine. This paper presents the final design of the cryo-module and the status of the construction of the main cryostat parts. Preliminary plans for the assembly and testing of the cryo-module at CERN are presented and discussed.

MOP089

Design of the ESS Spoke Cryomodule

vacuum, cryomodule, cavity, cryogenics

357

D. Reynet, S. Bousson, S. Brault, P. Duchesne, P. Duthil, N. Gandolfo, G. Olry, E. Rampnoux
IPN, Orsay, France

The European Spallation Source (ESS) project brings together 17 European countries to develop the world’s most powerful neutron source feeding multidisplinary researches. The superconducting part of the linear accelerator consists in 59 cryomodules housing different superconducting radiofrequency (SRF) resonators among which 28 paired β=0.5 352.2 MHz SRF niobium double Spoke cavities, held at 2K in a saturated helium bath. A prototype Spoke cryomodule with two cavities equipped with their 300kW RF power couplers is now being designed and will be constructed and tested at full power by the end of 2015 for the validation of all chosen technical solutions. It integrates all the interfaces necessary to be operational within a linac machine. Its assembly requires dedicated tooling and procedures in and out of a clean room. The design takes into account an industrial approach for the management of the fabrication costs. This prototype will have to guarantee an accelerating field of 8MV/m while optimizing the energy consumption and will aim at assessing the maintenance operations issues. We propose to present the design of this cryomodule and its related tooling.

MOP092

Computation of Wakefields and HOM Port Signals by Means of Reduced Order Models

wakefield, impedance, cavity, HOM

364

J. Heller, T. Flisgen, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

The investigation of wakefields is an important task in the design and operation of particle accelerators. Computer simulations are a reliable tool to extend the understanding of these effects. This contribution presents an application example of a new method to compute wakefields as well as parameters derived from those fields, such as higher order mode (HOM) port signals. The method is based on a reduced order model of the structure created by as set of 3D eigenmodes, a set of 2D waveguide port modes and the current density of the beam. In contrast to other wakefield computations, the proposed method operates directly on the reduced order model. Therefore, once having established this model, the beam-excited fields can be determined quickly for different beam parameters. As a matter of fact, only a small part of the reduced system has to be recomputed for every sweep point. From these advantages it is obvious, that the method is highly compatible for beam parameter studies. In a proof of principal the effectiveness of the method compared to established methods of wakefield computations in terms of computational time and accuracy is shown.

TUP051

Horizontal High Pressure Water Rinsing for Performance Recovery

cavity, cryomodule, vacuum, factory

527

Y. Morita, K. Akai, T. Furuya, A. Kabe, S. Mitsunobu, M. Nishiwaki
KEK, Ibaraki, Japan

Eight superconducting accelerating cavities were operated for more than ten years at the KEKB machine. Those cavities are also used at SuperKEKB. During the KEKB operation, Q values of some cavities were degraded. Cause of the degradation was contamination by air dusts at a repair of vacuum seals or a gasket replacement of input couplers. So far, those degradations are acceptable for the SuperKEKB operation, however, further degradation will make the operation unstable and, in the worst case, make it impossible. High pressure rinsing (HPR) is an effective method to clean the cavity surface. In order to apply HPR, however, the cavity has to be disassembled from a cryomodule. The disassembly takes time and costs. Furthermore, re-sealed vacuum flanges bring the risk of vacuum leakage again. Therefore we have developed a horizontal HPR. This method applies a high pressure water jet that is inserted horizontally into the cavity in the cryomodule. The wasted water is extracted with an aspirator. This method does not require the disassembly. We applied the horizontal HPR to our degraded cavity. Its RF performance has been successfully recovered.

TUP062

Application of In-Vacuum Infrared Pyrometry During Fabrication of European XFEL Niobium Cavities

cavity, vacuum, electron, niobium

570

L. Monaco, P. Michelato, D. Sertore
INFN/LASA, Segrate (MI), Italy
V. Battista, G. Corniani, M. Festa
Ettore Zanon S.p.A., Schio, Italy
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy

A technique to measure the temperature of Niobium components in vacuum during Electron Beam Welding (EBW) operation is presented and results obtained on the large scale cavity production for the European XFEL are discussed. During the EBW process, the knowledge of the components temperature during the welding operation could help both for the better choice of the welding parameters and for the optimization of the production cycle. In collaboration with the Italian firm Ettore Zanon (EZ), we developed a system able to measure the temperature of Nb components in vacuum during EBW operation using a IR pyrometer placed outside the vacuum chamber through an appropriate vacuum viewport. In the paper the experience of this device during the production of Nb components for the XFEL 1.3 GHz cavity production is discussed.

TUP069

The Copper Substrate Developments for the HIE-ISOLDE High-Beta Quarter Wave Resonator

cavity, electron, cryogenics, linac

596

L. Alberty, G. Arnau-Izquierdo, I. Aviles Santillana, S. Calatroni, O. Capatina, A. D'Elia, G. Foffano, Y. Kadi, P. Moyret, K.M. Schirm, T. Tardy, W. Venturini Delsolaro
CERN, Geneva, Switzerland
A. D'Elia
UMAN, Manchester, United Kingdom

A new linac using superconducting quarter-wave resonators (QWR) is under construction at CERN in the framework of the HIE-ISOLDE project. The QWRs are made by Niobium sputtered on a bulk Copper substrate. The working frequency at 4.5 K is 101.28 MHz and they will provide 6 MV/m accelerating gradient on the beam axis with a total maximum power dissipation of 10 W. The properties of the cavity substrate have a direct impact on the final cavity performance. The Copper substrate has to ensure an optimum surface for the Niobium sputtered layer. It has also to fulfill the required geometrical tolerances, the mechanical stability during operation and the thermal performance to optimally extract the RF dissipated power on cavity walls. The paper presents the mechanical design of the high β cavities. The procurement process of the Copper raw material is detailed, including specifications and tests. The manufacture sequence of the complete cavity is then explained and the structural and thermo-mechanical behavior during the tests performed on a prototype cavity is discussed. The industrialization strategy is presented in view of final production of the cavities.

TUP072

Quality Factor Measurements of the Ultramet 3 GHz Cavity Constructed Using Chemical Vapour Deposition

cavity, niobium, SRF, radio-frequency

607

D.L. Hall, D. Gonnella, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
V.M. Arrieta, S.R. McNeal
Ultramet, California, USA

Funding: US Department of Energy Phase 1 Small Business Innovation Research award to Ultramet
A seamless 3 GHz bulk niobium cavity constructed by Ultramet using rapid chemical vapor deposition (CVD) techniques has been tested on the vertical SRF test stand at Cornell. The cavity received a 25 um buffered chemical polish (BCP) and 700 C heat treatment for 4 days. First test results gave an intrinsic quality factor of Q0 = (1.55 ± 0.12) x 10⁷ and (2.00 ± 0.15) x 10⁷ at 4.2 K and 1.5 K, respectively. A second BCP removed 100 um of material, after which test results improved to Q0 = (7.59 ± 1.52) x 10⁷ and (4.16 ± 0.31) x 10⁸ at 4.2 K and 1.5 K. During the ﬁrst test poor coupling to the input ampliﬁer impeded tests at accelerating ﬁelds >0.2 MV/m, while during the second test the cavity quenched at 1.3 MV/m when operating at 1.5 K. An optical inspection of the cavity after the second test revealed the presence of at least 4 pits on the upper hemisphere suggesting an area of higher than average surface resistance that may have contributed to the low ﬁeld quench via thermal runaway. The potential of CVD as a construction method for SRF cavities is discussed.

TUP087

RF Test Results of the first Nb3Sn Cavities Coated at Cornell

cavity, niobium, SRF, linac

666

S. Posen, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

As an alternative material to niobium for SRF cavities in particle accelerators, Nb3Sn presents two significant advantages. With a Tc of 18 K, it has a very small surface resistance at a given temperature, leading to a significant reduction in cryogenic costs; and with a predicted Hsh of nearly 400 mT, it has the potential to produce cavities with higher gradients and therefore shorter high energy linacs. Recently, two 1.3 GHz cavities have been fabricated and coated with Nb3Sn at Cornell. Tests of these first cavities have produced encouraging results, including a very high Tc and some very high-performing surface regions. These cavity results as well as new results of samples studied using TEM will be presented.

TUP095

Field Emission and Consequences as Observed and Simulated for CEBAF Upgrade Cryomodules

cavity, neutron, electron, radiation

694

F. Marhauser, R.P. Johnson, R. Rodriguez
Muons, Inc, Illinois, USA
P. Degtiarenko, A. Hutton, G. Kharashvili, C.E. Reece, R.A. Rimmer
JLAB, Newport News, Virginia, USA

High gamma and neutron radiation levels were monitored at the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Laboratory (JLab) after installation of new cavity cryomodules and initial test runs in the frame of the ongoing 12 GeV upgrade program. The dose rates scaled exponentially with cavity accelerating fields, but were independent of the presence of an electron beam in the accelerator. Hence, field emission (FE) is the source of origin. This has led to concerns regarding the high field operation (100 MV per cryomodule) in the future 12 GeV era. Utilizing supercomputing, novel FE studies have been performed with electrons tracked through a complete cryomodule. It provides a principal understanding of experimental observations as well as ways to mitigate FE as best as practicable by identification of problematic cavities.

TUP100

Medium Field Q-Slope Studies in High Frequency Cavities

cavity, superconductivity, niobium, factory

705

O.S. Melnychuk, A. Grassellino, A.I. Sukhanov
Fermilab, Batavia, USA

A phenomenon of Medium Field Q-Slope (MFQS) in superconducting RF cavities is of high importance because it occurs in the field range (5-20MV/m) that includes designed operation fields of future CW accelerators. MFQS impacts resistive losses in the cavity and, consequently, directly affects accelerator operation costs. We present studies of MFQS based on vertical test data for 1.3GHz nine-cell cavities and make comparisons of vertical test data from different laboratories.

TUP106

Second-Sound Measurements on a 3 GHz SRF Cavity at Low Acceleration Fields*

cavity, electron, acceleration, scattering

728

S.T. Sievers, U. Bonnes, C. Burandt, F. Hug, T. Kürzeder, N. Pietralla, A. Richter
TU Darmstadt, Darmstadt, Germany

Funding: *This work is supported by the DFG through the Collaborative Research Center SFB 634.
The superconducting Darmstadt electron linear accelerator S-DALINAC uses 20-cell niobium cavities that are operated at a microwave frequency of 3 GHz in liquid helium at a temperature of 2 K. This operation temperature is well below TC = 9.25 K of niobium and guarantees superconducting condition in routine operation. Occasional surface impurities, in particular after venting the beamline following maintenance work, can lead to local quenches which destroy superconductivity of the cavity. In such events it is desirable to have a method for locating and eliminating these surface impurities. In order to locate quench sites in the superconducting cavities during operation in liquid helium a set-up of oscillating superleak transducers (OSTs) was tested in a vertical bath cryostat on a cavity known to quench at very small accelerating fields. Despite the low rf power of approximately 4 W needed to quench the cavity, we were able to identify the quench sites with the OST set-up. Subsequent optical inspection clearly showed surface damages at the determined positions. We will report on our set-up and the procedure.

TUP114

XT-map System for Locating SC Cavity Quench Position

cavity, cryogenics, survey, accelerating-gradient

747

H. Tongu, Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
H. Hayano, Y. Yamamoto
KEK, Ibaraki, Japan

XT-map system under development in collaboration between Kyoto University and KEK is a combined system of the temperature mapping (T-map) and X-ray mapping (X-map). High resolution T-map at quench detection will give more information for improving yield in production of high performance SC Cavities. The high-density sensor distribution of the XT-map gives the high resolution. Because the huge amount of sensor lines are multiplexed at a hi-speed scanning rate in the vicinity of the sensors, the small number of signal lines makes the installation process easy and reduces the system complexity. The scanning test of this XT-map system has been performed in the vertical test at KEK. The detected quench events will be reported.

THIOA01

Infrastructure, Methods and Test Results for the Testing of 800 Series Cavities for the European XFEL

cavity, coupling, controls, feedback

812

D. Reschke
DESY, Hamburg, Germany

Funding: The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no 283745 (CRISP).
The main linac of the European XFEL will consist of 100 accelerator modules, i.e. 800 superconducting accelerator cavities operated at a design gradient of 23.6 MV/m. The fabrication and surface preparation of the cavities in industry is in full swing. This talk describes the infrastructure and procedures of the vertical acceptance test in the "Accelerator Module Test Facility AMTF" at DESY. The present status of the test results is given.

Slides THIOA01 [1.998 MB]

THIOA05

Optimization of SRF Linacs

cryomodule, cavity, linac, cryogenics

830

T. Powers
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S.
This work describes preliminary results of a new software tool that allows one to vary parameters and understand the effects on the optimized costs of construction plus 10 year operations of an SRF linac, the associated cryogenic facility, and controls, where operations includes the cost of the electrical utilities but not the labor or other costs. It derives from collaborative work done with staff from Accelerator Science and Technology Centre, Daresbury, UK several years ago while they were in the process of developing a conceptual design for the New Light Source project. The initial goal was to convert a spread sheet format to a graphical interface to allow the ability to sweep different parameter sets. The tools also allow one to compare the cost of the different facets of the machine design and operations so as to better understand the tradeoffs. More recent additions to the software include the ability to save and restore input parameters as well as to adjust the Qo versus E parameters in order to explore the potential costs savings associated with doing so.

Slides THIOA05 [2.712 MB]

THIOC04

Demonstration of RF Stabilities in STF 9-cell Cavities Aiming for the Near Quench Limit Operation

cavity, feedback, LLRF, controls

865

M. Omet
Sokendai, Ibaraki, Japan
T. Matsumoto, S. Michizono, T. Miura
KEK, Ibaraki, Japan

In preparation of ILC an operation of two superconducting cavities controlled by digital LLRF techniques at different gradients (16 MV/m, 24 MV/m) with flat flattops and a 6.4 mA beam was demonstrated, which is only possible by PkQL control (individual setting of driving power and loaded Q per cavity). The vector sum stabilities were ΔA/A = 0.009%rms and Δφ = 0.009°rms. Since in ILC the cavity gradient spread is large (31.5 MV/m±20%) the required range of loaded Q values is 3·10⁶ to 10⁷. High loaded Q operation with a 6.1 mA beam at 2·10⁷ was demonstrated. The stabilities were ΔA/A = 0.008%rms and Δφ = 0.014°rms. Furthermore a near klystron operation within 5% of saturation was performed with a 6.2 mA beam. The stabilities were ΔA/A = 0.010%rms and Δφ = 0.009°rms.

Slides THIOC04 [1.448 MB]

THIOD01

SRF Cavities for ADS Project in China

cavity, linac, SRF, proton

868

Y. He, W.M. Yue, S.H. Zhang
IMP, Lanzhou, People's Republic of China
J.P. Dai, Z.Q. Li, Z.C. Liu, W.M. Pan
IHEP, Beijing, People's Republic of China
X.Y. Lu
PKU, Beijing, People's Republic of China

The driver linac for ADS project in China is full superconducting downstream of Radio Frequecy Quadrupole Accelerator. It is a key technology R&D stage of the project from 2011 to 2015. Superconducting HWR, Spoke, and elliptical cavities are all involved in the project. The prototypes of 162.5 MHz HWR010, 325 MHz Spoke012, 325 MHz Spoke021, 325 MHz Spoke040, and 650 MHz elliptical 063 are being developed at IMP and IHEP in China. A small number of HWR010 and Spoke012 have been produced and vertically tested. The first prototype of Spoke021 were tested too. The design, performances, fabrication, suface processing, and testing of all cavities will be presented in the talk. The design improvement of the cavities in the future will also be discussed.

Slides THIOD01 [13.465 MB]

THIOD02

Faced Issues in ReA3 Quarter-Wave Resonators and Their Successful Resolution

cavity, vacuum, linac, cryomodule

873

A. Facco
NSCL, East Lansing, Michigan, USA
C. Compton, J.L. Crisp, K. Elliott, A. Facco, M. Hodek, M.J. Johnson, M. Leitner, I.M. Malloch, D. Miller, S.J. Miller, D. Morris, D. Norton, R. Oweiss, J.P. Ozelis, J. Popielarski, L. Popielarski, K. Saito, N.R. Usher, G.J. Velianoff, D.R. Victory, J. Wei, K. Witgen, Y. Xu, S. Zhao
FRIB, East Lansing, Michigan, USA
A. Facco
INFN/LNL, Legnaro (PD), Italy

Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
The 80.5 MHz, β=0.085 QWR production cavities for the ReA3 project at MSU have initially shown puzzling behavior and unexpected lack of performance. This was due to a combination of design problems and subtle mechanical effects which have been pointed out during a brief but intense testing campaign made by the FRIB SRF group. The same cavities could be eventually refurbished and brought to performance well above original specifications. This work will be presented with emphasis to the technical problems encountered, their diagnosis and the adopted solutions.

Slides THIOD02 [8.256 MB]

THP003

Cold Measurements on the 325 MHz CH-Cavity

cavity, linac, coupling, ion

896

M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
M. Amberg
HIM, Mainz, Germany

Funding: GSI, BMBF Contr. No. 06FY7102, 06FY9089I
At the Institute for Applied Physics (IAP), Frankfurt University, a sc 325 MHz CH-Cavity has been designed and built. This 7-cell cavity has a geometrical beta of 0.16 corresponding to a beam energy of 11.4 AMeV. The design gradient is 5 MV/m. Novel features of this resonator are a compact design, low peak fields, easy surface processing and high power coupling. After successful tests at Research Instruments (RI) and in Frankfurt the cavity was processed and cleaned at RI and power tests at 4K have been performed at the cryo lab in Frankfurt. In this paper these measurements will be presented.

THP004

Design Progress of SSR1 Single Spoke Resonator for RAON

cavity, superconducting-cavity, simulation, acceleration

899

H.J. Cha, D. Jeon, H.C. Jung, H.J. Kim, G.-T. Park
IBS, Daejeon, Republic of Korea
R.E. Laxdal, Z.Y. Yao, V. Zvyagintsev
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

Funding: The Ministry of Science, ICT and Future Planning (MSIP) and the National Research Foundation (NRF) of the Republic of Korea under Contract 2011-032011
An advanced heavy ion accelerator for basic sciences and multiple applications, called “RAON”, is under construction in Daejeon, South Korea. The fabrication of prototypes for four different types of superconducting cavities, QWR, HWR, SSR1 and SSR2, is scheduled based on the on-going technical designs. In this paper, we present the electromagnetic and mechanical analyses for the SSR1 cavity (β=0.3 and f=325 MHz). Several variants have been considered and compared in terms of rf parameters, multipacting sensitivity, helium pressure sensitivity and ease of fabrication. This includes an analysis of stiffening rings and helium jacket design for stable operation. The progress towards the design of the SSR1 cavity will be given.

THP005

Characteristics and Fabrication of Spoke Cavities for High-Velocity Applications

cavity, vacuum, target, superconductivity

902

C.S. Hopper, J.R. Delayen, H. Park
ODU, Norfolk, Virginia, USA
J.R. Delayen, H. Park
JLAB, Newport News, Virginia, USA

A 500 MHz, velocity-of-light, two-spoke cavity has been designed and optimized for possible use in a compact light source [1]. Here we present the mechanical analysis and steps taken in fabrication of this cavity at Jefferson Lab.
*[1] T. Satogata et al, “Compact Accelerator Design for a Compact Light Source,” IPAC13, Shanghai, China, May 2013.

THP012

Rebuild of Capture Cavity 1 at Fermilab

cavity, cryomodule, vacuum, SRF

917

E.R. Harms, T.T. Arkan, E. Borissov, N. Dhanaraj, A. Hocker, Y.O. Orlov, T.J. Peterson, K.S. Premo
Fermilab, Batavia, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The front end of the proposed Advanced Superconducting Test Accelerator at Fermilab employs two single cavity cryomodules, known as ‘Capture Cavity 1’ and ‘Capture Cavity 2’, for the first stage of acceleration. Capture Cavity 1 was previously used as the accelerating structure for the A0 Photoinjector to a peak energy of ~14 Mev. In its new location a gradient of ~25 MV/m is required. This has necessitated a major rebuild of the cryomodule including replacement of the cavity with a higher gradient one. Retrofitting the cavity and making upgrades to the module required significant re-design. The design choices and their rationale, summary of the rebuild, and early test results are presented.

THP017

Mechanical Study on the Cavity Package of 1.3 GHz Superconducting Accelerating Unit at IHEP

cavity, simulation, cryomodule, SRF

926

S. Jin, J. Gao, Z.C. Liu, J.Y. Zhai, H.J. Zheng
IHEP, Beijing, People's Republic of China

The program of 1.3GHz Superconducting RF (SRF) Accelerating Unit is under study at IHEP. A scheme of the unit structure is shown as fig. 1. In the unit, a 9-cell SRF cavity, tuner and a liquid helium (LHe) tank including a section of 50mm long, 0.3mm thick bellows will be welded and assembled together to form a relatively independent component called cavity package. In the study, mechanical analyses are carried out focusing on the package to assure its safety in the fabrications or other room temperature measurements. A commercial program of ANSYS Workbench is used.

THP024

Lorentz Force Detuning Simulations of Spoke Cavities With Different Stiffening Elements

cavity, simulation, radiation, vacuum

946

J.L. Muñoz, F.J. Bermejo
ESS Bilbao, Zamudio, Spain

Lorentz force detuning caused by radiation pressure on the Nb cavity walls is of concern in cavity design and operation since its magnitude can approach the cavity bandwidth. This effect can be reduced using pasive stiffening elements in the cavity. In this work, Lorentz force detuning has been studied by numerical simulations for spoke cavities. Different stiffening elements has been considered. Static and dynamic behaviour have been analyzed by means of 3D static and transient electromagnetic and mechanical coupled finite elements simulations.

THP029

Simulation of Mechanical Resonances of SRF Cavities in Low Beam Current CW Operation

cavity, resonance, simulation, cryomodule

962

N. Solyak, M.H. Awida, I.V. Gonin, T.N. Khabiboulline, Y.M. Pischalnikov, W. Schappert, V.P. Yakovlev
Fermilab, Batavia, USA

The low beam current for CW operation of the Project X requires cavities to be mechanically optimized to operate at a high loaded Q and thus, low bandwidth with higher sensitivity to microphonics. The essential source of microphonics detuning is fluctuations in the helium pressure df/dp. Last year’s several methods for reducing df/dp has been proposed. One of the other possible sources of RF frequency instability is mechanical resonances. The cavity could be driven out of operating frequency by the mechanical deformations due to vibrations caused by external factors. In this paper we present the COMSOL multiphysics algorithm developed for evaluation of operating frequency shift due to mechanical resonances in SC cavities. We discuss the results of simulations for 5-cell elliptical 650 MHz β=0.9 cavities. The comparison of COMSOL simulations and measurements of ILC type cavities in Horizontal Test Stand at Fermilab is presented.

THP033

Study of Balloon Spoke Cavities

cavity, TRIUMF, simulation, proton

972

Z.Y. Yao, R.E. Laxdal, B.S. Waraich, V. Zvyagintsev
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
R. Edinger
PAVAC, Richmond, B.C., Canada

A balloon geometry has been proposed to suppress multipacting for single spoke resonators. The design may find a useful application for proton and ion accelerator projects. TRIUMF has completed initial RF, mechanical, and fabrication studies on this special geometry for both low (β=0.12) and medium (β=0.3) β geometries. The RF properties are comparable with that of traditional spoke cavities but with improved RF efficiency in addition to the reduced multipacting. The results of electro-magnetic and structural design studies comparing the balloon geometry with traditional spoke geometries will be presented. We will also present optimization studies of the mechanical design, such as decreasing df/dp by EM field compensation as well as discussing tuning strategies and fabrication techniques.

THP034

Multipacting Suppression in a Single Spoke Cavity

cavity, electron, resonance, simulation

975

Z.Y. Yao, R.E. Laxdal, V. Zvyagintsev
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
X.Y. Lu, K. Zhao
PKU, Beijing, People's Republic of China

Spoke cavities are good candidates for the low and medium β section of a high intensity proton or ion accelerator. For many high intensity accelerators, stability and reliability are the most important properties. Currently, one of the key issues of spoke cavity performance is multipacting, which may cause instability during operation. Multipacting in a spoke cavity has a troublesome characteristic as it presents a continual barrier over a wide gradient range, usually in the range of operation from 3MV/m to 15MV/m. A good surface processing can improve the secondary electron emission yield. However, the complex 3D structure makes it not easily achievable as with the elliptical cavity variants. Suppressing multipacting in the design stage is clearly advantageous. This paper will present a multipacting study based on the PKU-I spoke cavity. A systematic correlation between geometric parameters and multipacting behaviors is obtained. Based on this study a new geometry of single spoke cavity called the ‘balloon’ variant is proposed.

THP046

Magnetic Material Characterization & SC Solenoid Coil Package Design for FRIB

solenoid, shielding, cavity, cryogenics

1009

K. Saito, S. Chouhan, C. Compton, J. DeKamp, M. Leitner, F. Marti, J.P. Ozelis, S. Shanab, G.J. Velianoff, X. Wu, Y. Yamazaki, A. Zeller, Y. Zhang, Q. Zhao
FRIB, East Lansing, Michigan, USA
S.K. Chandrasekaran
MSU, East Lansing, USA
K. Hosoyama
KEK, Ibaraki, Japan

To date SRF technology is extending to large scale heavy ion LINACs, where SRF cavities accelerate beams from very low energy to high energy. In this application, superconducting (SC) solenoids are installed inside the cryomodule to provide strong beam focusing with enhanced space efficiency. FRIB will use local magnetic shielding, where magnetic shielding by Cryoperm or A4K is located close to the cavity at 2K. In this scheme rather strong magnetic fringe fields from the SC solenoid expose the shielding material and will magnetize it. An efficient degaussing process is required as cure against such magnetization. Magnetic material characterization of magnetic shielding materials is very important to be able to plan effective degaussing procedures. The paper will also discuss the design of FRIB solenoids optimized for cost, reliability, and robust long-term operation. NbTi wire performance criteria are discussed in addition to solenoid operational margins.

THP049

SPL RF Coupler Cooling Efficiency

cryomodule, radiation, framework, cavity

1019

R. Bonomi, O. Capatina, E. Montesinos, V. Parma, A. Vande Craen
CERN, Geneva, Switzerland

Energy saving has become an important challenge in accelerator design. In this framework, reduction of heat loads in a cryomodule is of fundamental importance due to the small thermodynamic efficiency of cooling at low temperatures. In particular, care must be taken during the design of its critical components (RF couplers, cold-warm transitions, ..). In this framework, the main RF coupler of the Superconducting Proton Linac cryomodule at CERN will not only be used for RF powering but also as the main mechanical support of the superconducting cavities. These two functions have to be accomplished while ensuring the lowest heat in-leak to the helium bath at 2 K. In the SPL design, the RF coupler outer conductor is composed of two walls and cooled by forced convection with helium gas at 4.5 K. Analytical, semi-analytical and numerical analyses are presented in order to defend the choice of gas cooling. Temperature profiles and thermal performance have been evaluated for different operating conditions; a sensitivity analysis of RF currents node position along the wall has also been performed. Finally, comparison with respect to other heat extraction methods is presented.

THP053

Development of Quality Control Procedures for the Processing of ReA3 Copper Plated Fundamental Power Coupler

controls, cavity, detector, SRF

1031

R. Oweiss, J.L. Crisp, A. Facco, M. Leitner, D. Morris, J. Popielarski
FRIB, East Lansing, Michigan, USA
A. Facco
INFN/LNL, Legnaro (PD), Italy
L. Popielarski, J. Wenstrom
NSCL, East Lansing, Michigan, USA

The processing of copper plated fundamental power couplers (FPCs) has posed major risks to the successful performance of superconducting cavities. This paper discusses the lessons learnt throughout the development of quality control procedures for the ReA3 copper plated FPCs. Michigan State University (MSU) Re-Accelerator project (ReA3) utilizes eight copper plated coaxial FPCs to power the 80.5 MHz=0.085 quarter-wave resonators (QWRs) for which baseline quality control procedures are established. The effectiveness of visual inspection process using the microscope & borescope to qualify FPC components is evaluated. The adaptive use of quality control diagnostic devices as the liquid particle counter, surface particle detector & desiccator for the clean processing & assembly is assessed. A summary of the collaborative work to refine and optimize FPC design & processing in correlation to cavity performance and experimental results is presented.
*This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE SC0000661.

THP056

Validation Procedures for the IFMIF Power Coupler Prototypes

vacuum, controls, target, linac

1043

H. Jenhani, P. Carbonnier, Y. Gasser, N. Grouas, P. Hardy, V.M. Hennion, F. Orsini, Y. Penichot, B. Renard, D. Roudier
CEA/IRFU, Gif-sur-Yvette, France
S.J. Einarson, T.A. Treado
CPI, Beverley, Massachusetts, USA
D. Regidor, M. Weber
CIEMAT, Madrid, Spain

In the framework of the International Fusion Materials Irradiation Facility (IFMIF), which consists of two high power CW accelerator drivers, each delivering a 125 mA deuteron beam at 40 MeV, a Linear IFMIF Prototype Accelerator (LIPAc) is presently under design for the first phase of the project. The first two IFMIF Power Coupler Prototypes were manufactured for LIPAc. Series of acceptance tests have been performed successfully. Prototype Power Couplers have been then cleaned and assembled in an ISO 5 cleanroom. A dedicated test bench allowing RF conditioning of the couplers up to 200 kW CW at 175 MHz was achieved. RF power conditioning is planned to start during October 2013.

THP059

HOM Coupler Design Adjustment for CW operation of the 1.3 GHz 9-cell TESLA Type SRF Cavity

HOM, dipole, cavity, simulation

1051

D. Kostin, W.-D. Möller, J.K. Sekutowicz
DESY, Hamburg, Germany

One of the key features of a modern research facility is its versatility, ability to adjust for a multitude of the applications and user needs. A challenge for the coming European XFEL is to become a multipurpose laboratory with a broad applications spectrum. Primarily, the XFEL is a pulsed machine. Encompassing the CW mode would be a worthy addition. CW operation of the 1.3GHz 9-cell TESLA Type SRF Cavity was performed several times at DESY and other Labs successfully. One of the difficulties was a heat load of the High Order Mode (HOM) couplers. To amend this HOM coupler design adjustement is proposed, simulated and modelled. Results are presented and discussed.

THP060

High Power RF Coupler for ADS Accelerating Cavities

cavity, simulation, linac, Windows

1055

S.V. Kutsaev, M.P. Kelly, B. Mustapha, J.A. Nolen, P.N. Ostroumov
ANL, Argonne, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
Accelerator driven systems (ADS) require a high-power CW proton accelerator with proton beam energy near 1 GeV. High-gradient superconducting TEM-cavities are a natural choice for the front end of linac. This paper presents the design of superconducting low-beta half wave resonator operating at 162 MHz frequency for ADS, as well as a new 75 kW power coupler that has been designed at Argonne National Laboratory. This coupler would permit operations with an accelerating voltage of 3.0 MV with a beam current of 25 mA. The coupler includes a cold RF window which keeps the antenna at low temperature and a variable bellows section to adjust the coupling factor. The importance of these features for reliable operation will be discussed in detail.

THP061

Developments of HOM Dampers for SuperKEKB Superconducting Cavity

cavity, HOM, simulation, factory

1058

M. Nishiwaki, K. Akai, T. Furuya, A. Kabe, S. Mitsunobu, Y. Morita
KEK, Ibaraki, Japan

Eight superconducting accelerating cavities were stably operated under a high beam current and a large beam induced HOM power in KEKB electron ring. The HOM power of 16 kW at the beam current of 1.4A was absorbed in two ferrite dampers attached to each cavity. In SuperKEKB, that is the upgrade machine of KEKB, the design beam current is 2.60 A. The HOM power of higher than 40 kW is expected to be induced. To cope with the large HOM power, precise evaluations of HOM power loads including HOM dampers were carried out. Then, new ferrite dampers with reinforced water cooling were developed and high-power tested. On the other hand, the evaluation indicated that an additional HOM damper can absorb significant amount of HOM power. Additional damper is effective to reduce each ferrite damper load. In this report, we will describe the results of high power tests of the new ferrite dampers, studies for additional dampers, and an installation plan for SuperKEKB.

THP062

Optimisation of the 3-Stub Tuner for Matching the Diamond SCRF Cavities

cavity, simulation, coupling, storage-ring

1061

S.A. Pande, C. Christou, P. Gu, M. Jensen
Diamond, Oxfordshire, United Kingdom

The Diamond Storage Ring cavities are aperture coupled resulting in a fixed external Q. This results in the cavities being matched under certain conditions depending on the loss per turn, the beam current and the accelerating voltage. Operationally, there are advantages to limiting the accelerating voltage to improve reliability and lifetime, which at high beam current results in a mismatch and high reflected power. To match the cavities under such non-optimum operating conditions we use 3-stub tuners in the waveguide feeds. It has been observed, that certain configurations of the 3-stub tuners can improve the match of the cavity, but this can result in strong heating of the waveguide in the cryostat. Numerical simulations of the cavity along with the coupling waveguide and 3-stub tuners have been carried out using CST Studio for different beam loading conditions to optimise the 3-stub tuners for acceptable match and heating. In this paper we present the results of our simulations and comparisons with measurements for operation with different beam currents and cavity voltages.

THP065

Design of 352.21 MHz RF Power Input Coupler and Window for the European Spallation Source Project (ESS)

cavity, multipactoring, vacuum, SRF

1069

E. Rampnoux, S. Bousson, S. Brault, P. Duchesne, P. Duthil, G. Olry, D. Reynet
IPN, Orsay, France

A 352.21 MHz RF high power coupler window was designed by IPNO to meet the specification requirements for the ESS accelerator project. This designed is based on IPNO’s power coupler developments performed in the framework of the EURISOL Design Study project for which two power couplers using coaxial technology without chokes systems around the ceramic disc have been designed and tested successfully up to 20 kW RF power level in CW mode. For ESS project, the RF power input window was developed and designed to reliability operate at an average power level of 25 kW up to 300 kW in pulsed and continuous wave modes. This 352.21 MHz RF window was developed to remove the chocks usually used and provided the following advantages: more reliability, less expensive to manufacture, better vacuum, easier cleaning, less secondary electron-multipacting with specificity to present a bandwidth close to 1 GHz.

THP066

SARAF Phase-I HWR Coupler Cooling Design

simulation, linac, cavity, proton

1073

J. Rodnizki, Y. Ben Aliz, I. Fishman, A. Grin, Z. Horvitz, B. Kaizer, L. Weissman
Soreq NRC, Yavne, Israel

The Soreq Applied Research Accelerator Facility (SARAF) design is based on a 40 MeV 5 mA light ions superconducting RF linac. Phase I of SARAF delivers up to 2 mA CW proton beam in an energy range of 1.5-4.5 MeV. The maximum beam power that we have reached is 4.5 kW. The warming of the SARAF linac RF couplers is currently the main limiting factor for reaching higher CW beam power. The coupler cooling configuration was optimized by increasing the cold window copper braid and adding a copper braid to the top end, using CST Multiphysics and ANSYS steady state and transient solvers. The study was conducted for the heat load generated by the surface currents of a matched 4 kW forward CW power, simulated by the CST MWS FD solver. Multipacting is a known potential heat source that overheats the coupler in the vicinity of the cold window. The coupler overheat phenomena was experimentally studied as a function of DC bias voltage, and it was found that a 900 V bias reduces significantly the heating rate. As a result we expect that the beam power can be significantly increased. The long overheat period implies that optimization of the cooling configuration is still needed.

THP068

New Design of HOM Coupler Using Coaxial-like Rounded Waveguide

HOM, cavity, damping, simulation

1081

M. Sawamura
Japan Atomic Energy Agency (JAEA), Gamma-ray Non-Destructive Assay Research Group, Tokai-mura, Ibaraki-ken, Japan
R. Hajima, R. Nagai, N. Nishimori
JAEA, Ibaraki-ken, Japan

It is important to damp higher-order modes (HOMs) of superconducting accelerators especially for energy-recovery linacs of high current operation. Though various types of HOM couplers, beam line HOM dampers and waveguide HOM couplers have been developed, there are some problems such as inner conductor heating of output connector for HOM couplers and low packing factor for beam line HOM dampers. We propose new design of HOM coupler. This coupler consists of a coaxial line coupled with a cavity or a beam pipe and a rounded waveguide which cuts off the accelerating mode. The rounded waveguide is similar to a coaxial line and the inner conductor and outer conductor are connected with a plate which corresponds to waveguide side wall. This enables the inner connector cooled down efficiently through the outer conductor. The calculation results of MW-STUDIO will be presented.

THP072

Input Coupler for Cornell ERL Main Linac

linac, cavity, cryomodule, vacuum

1094

V. Veshcherevich, P. Quigley
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work is supported by the National Science Foundation grant DMR-0807731.
Each cavity of the Cornell ERL Main Linac has a single coaxial type input coupler with fixed coupling, Qext = 6.5×E7. The input coupler will operate at RF power up to 5 kW at full reflection. The coupler design is based on the design of TTF-III input coupler with appropriate modifications and with taking into account the Cornell experience with couplers for ERL Injector. Seven couplers have been fabricated by CPI, Beverly and tested at Cornell on the test stand up to 5 kW CW. No major issues were noticed during the test. One coupler was attached to the prototype linac cavity. The cavity was successfully tested with great results achieved inside the horizontal test cryomodule. Six other couplers will be installed in the Main Linac Cryomodule (MLC) Prototype.

THP077

Coaxial Blade Tuner for European XFEL 3.9 GHz cavities

cavity, linac, simulation, cryomodule

1101

R. Paparella, M. Bertucci, A. Bosotti
INFN/LASA, Segrate (MI), Italy
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy

The European XFEL linac injector features a third harmonic section jointly realized by INFN and DESY and hosting a 3.9 GHz 9-cell cavities cryomodule. The cold tuning system, developed by INFN for these cavities, is inspired by the coaxial Blade Tuner already qualified for ILC cavities. Design, fabrication and room temperature qualification of first tuner units produced are reviewed in this paper.

THP078

Deformation Tuner Design for a Double Spoke Cavity

cavity, cryomodule, SRF, linac

1104

N. Gandolfo, S. Bousson, S. Brault, P. Duchesne, P. Duthil, G. Olry, D. Reynet
IPN, Orsay, France

IPN Orsay is developing the low-beta double Spoke cavities cryomodule for the ESS. Based on previous successfully tested prototypes, a fast/slow tuner has been studied to compensate resonance frequency variations of the cavity during operation. The typical perturbations are coming from LHe pressure variations as well as microphonics and Lorentz force detuning (LFD). Two tuners are being built in order to validate both expected performances and series production feasibility. In this paper, the tuner design of the double Spoke cavity is presented.

THP080

SRF Cavity Tuning for Low Beam Loading

cavity, resonance, cryomodule, vacuum

1110

N. Solyak, E. Borissov, I.V. Gonin, C.J. Grimm, T.N. Khabiboulline, R.V. Pilipenko, Y.M. Pischalnikov, W. Schappert, V.P. Yakovlev
Fermilab, Batavia, USA

The design of 5-cell elliptical 650 MHz β=0.9 cavities to accelerate H⁻ beam of 1 mA average current in the range 467-3000 MeV for the Project X Linac is currently under development at Fermilab. The low beam current enables cavities to operate with high loaded Q’s and low bandwidth, making them very sensitive to microphonics. Mechanical vibrations and the Lorentz force can drive cavities off resonance during operation; therefore the proper design of the tuning system is very important part of cavity mechanical design. In this paper we review the design, performance, operation, reliability and cost of fast and slow tuners for 1.3 GHz elliptical cavities. We also present a design of the slow and fast tuners for 650 MHz β=0.9 cavities based on this experience. The HV in the new design is equipped with the tuners located at the end of the cavity instead of the initially proposed blade tuner located in the middle. We will present the results of ANSYS analyses of mechanical properties of tuners.

THP086

LLRF System Design and Performance for XFEL Cryomodules Continuous Wave Operation

cavity, feedback, LLRF, cryomodule

1129

J. Branlard, V. Ayvazyan, L. Butkowski, K.P. Przygoda, H. Schlarb, J.K. Sekutowicz
DESY, Hamburg, Germany
W. Cichalewski, A. Piotrowski
TUL-DMCS, Łódź, Poland
W. Jałmużna
Embedded Integrated Control Systems GmbH, Hamburg, Germany
J. Szewiński
NCBJ, Świerk/Otwock, Poland

The Cryomodule Test Bench (CMTB) at DESY is equipped with a 100 kW Inductive Output Tube (IOT) allowing the test of superconducting cryomodules in continuous wave (CW) operation mode. Although significantly different from the nominal pulsed operation mode of the European X-Ray Free Electron Laser (XFEL), CW operation can be handled by the same Low-level Radio Frequency (LLRF) system, within minor firmware modifications. The hardware details of the LLRF setup at CMTB, the firmware and software architecture and performance results from the last CW test are presented in this contribution.

THP087

LLRF Tests of XFEL Cryomodules at AMTF: First Experimental Results

cavity, cryomodule, LLRF, resonance

1132

J. Branlard, V. Ayvazyan, M.K. Grecki, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
W. Cichalewski, K. Gnidzińska, A. Piotrowski, K.P. Przygoda
TUL-DMCS, Łódź, Poland
W. Jałmużna
Embedded Integrated Control Systems GmbH, Hamburg, Germany

In preparation for the series production of cryomodules for the European X-ray Free Electron Laser (XFEL), three pre-series cryomodules and several prototypes have been produced and tested at the Cryomodule Test Bench (CMTB) and at the Accelerating Module Test Facility (AMTF) in DESY. Among the numerous tests performed on the modules, the low-level radio frequency (LLRF) tests aim at characterizing the performance of the modules from an RF controls perspective. These integration tests must take into account cavity tuners, cavity motorized couplers, quench gradients, microphonics, piezo control and the overall gradient performance of the cryomodule under test. In this paper, the LLRF-specific tests are summarized and the first experimental results obtained at CMTB and AMTF are presented.

THP096

Recent Upgrade of Ultra-Broadband RF System for Cavity Characterization

cavity, controls, software, pick-up

1151

S. Stark, V. Palmieri, A.M. Porcellato, A.A. Rossi
INFN/LNL, Legnaro (PD), Italy
V. Palmieri
Univ. degli Studi di Padova, Padova, Italy

The first computer controlled RF system for SC cavity characterization entered into operation at INFN-LNL in 1994. Since then it has been successfully used for testing SC cavities of different shapes and frequencies. Recently we performed an important upgrade on it in order to cover a wider frequency range and to take advantage of the better performance of nowadays electronic devices. The paper describes the present system layout, dedicated software, sequences of calibration and testing procedures and moreover discusses further upgrading possibilities.

FRIOA01

LHC Crab Cavity .Progress and Outlook

cavity, luminosity, cryomodule, dipole

1161

R. Calaga, E. Jensen
CERN, Geneva, Switzerland

Three novel superconducting RF crab cavity designs proposed for the LHC luminosity upgrade have rapidly progressed. First Niobium prototypes are reaching close to the design performance and beyond. The highlights of the RF test results from the prototypes along with design modifications for initial beam tests in the SPS are presented. The status of the cryomodule development, integration into the SPS and the beam tests in view of validating the crab cavity system for LHC upgrade are addressed.

Slides FRIOA01 [12.063 MB]

FRIOA03

Fabrication and Testing of Deflecting Cavities for APS

cavity, coupling, niobium, SRF

1170

J.D. Mammosser
JLab, Newport News, Virginia, USA
P. Dhakal, J. Henry, R.A. Rimmer, H. Wang, K.M. Wilson
JLAB, Newport News, Virginia, USA
J.F. Fuerst, J.P. Holzbauer, J.S. Kerby, A. Nassiri, G.J. Waldschmidt, G. Wu, Y. Yang
ANL, Argonne, USA
F. He
PKU, Beijing, People's Republic of China
Z. Li
SLAC, Menlo Park, California, USA

Abstract Jefferson Lab in Newport News, Virginia, in collaboration with Argonne National Laboratory, Argonne, Il, has fabricated and tested three production, 2.815 GHz crab cavities for Argonne’s Short-Pulse X-ray project. These cavities are unique in that the cavity and waveguides were milled from bulk large grain niobium ingot material directly from 3D CAD files. No forming of sub components was used with the exception of the beam-pipes. The cavity and helium vessel design along with the RF performance requirements makes this project extremely challenging for fabrication. Production challenges and fabrication techniques as well as testing results will be discussed in this paper.

Slides FRIOA03 [22.677 MB]

FRIOB02

Development and Performance of 325 MHz Single Spoke Resonators for Project X

cavity, vacuum, niobium, electron

1187

L. Ristori, M.H. Awida, P. Berrutti, C.M. Ginsburg, I.V. Gonin, T.N. Khabiboulline, M. Merio, T.H. Nicol, D. Passarelli, A.M. Rowe, D.A. Sergatskov, A.I. Sukhanov, V.P. Yakovlev
Fermilab, Batavia, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy.
Two types of single spoke resonators will be utilized for beam-acceleration in the low energy part of the Project X linac. SSR1 and SSR2 operate at 325 MHz and at an optimal beta of 0.22 and 0.51 respectively. After the initial phase of prototyping, a production run of 10 SSR1 resonators was recently completed in US industry. The qualification of this group of resonators in the Fermilab VTS is proceeding successfully and nearly complete. The first qualified resonator has been outfitted with a Stainless Steel helium vessel. Preliminary test results for the first jacketed SSR1 are presented. The first RF power couplers were ordered, the design of the double-lever tuning mechanism is almost complete.

Slides FRIOB02 [8.800 MB]

FRIOB04

CERN Developments for 704 MHz Superconducting Cavities

cavity, niobium, linac, proton

1198

O. Capatina, G. Arnau-Izquierdo, S. Atieh, I. Aviles Santillana, R. Bonomi, S. Calatroni, J.K. Chambrillon, R. Garoby, F. Gerigk, M. Guinchard, T. Junginger, M. Malabaila, L. Marques Antunes Ferreira, S. Mikulas, V. Parma, T. Renaglia, K.M. Schirm, T. Tardy, M. Therasse, A. Vacca, N. Valverde Alonso, A. Vande Craen
CERN, Geneva, Switzerland
F. Pillon
Kraftanlagen Nukleartechnik GmbH, Heidelberg, Germany

The Superconducting Proton Linac (SPL) is an R&D effort coordinated by CERN in partnership with other international laboratories. It is aiming at developing key technologies for the construction of a multi-megawatt proton linac based on state-of-the-art RF superconducting technology, which would serve as a driver in new physics facilities for neutrinos and/or Radioactive Ion Beam (RIB). Amongst the main objectives of this R&D effort, is the development of 704 MHz bulk niobium β=1 elliptical cavities, operating at 2 K with a maximum accelerating gradient of 25 MV/m, and the testing of a string of cavities integrated in a machine-type cryomodule. The cavity together with its helium tank had to be carefully designed in coherence with the innovative design of the cryomodule. New fabrication methods have also been explored. Five such niobium cavities and two copper cavities are in fabrication. The key design aspects are discussed, the results of the alternative fabrication methods presented and the status of the cavity manufacturing and surface preparation is detailed.

Slides FRIOB04 [8.677 MB]

FRIOC01

Design of the 352 MHz, Beta 0.50, Double-Spoke Cavity for ESS

cavity, cryomodule, simulation, niobium

1212

P. Duchesne, S. Bousson, S. Brault, P. Duthil, G. Olry, D. Reynet
IPN, Orsay, France
S. Molloy
ESS, Lund, Sweden

The ESS proton accelerator contains a superconducting sector consisting in three families of superconducting radiofrequency (SRF) bulk niobium cavities, operating at a nominal temperature of 2K: a family of Spoke cavities for the medium energy section followed by two families of elliptical cavities for higher energies. The superconducting Spoke section, having a length of 58.6m, consists of 14 cryomodules, each of them housing two 352.2 MHz β=0.50 Double-Spoke Resonators (DSR). The operating accelerating field is 8MV/m. The choice of the Spoke technology is guided by the high performances of such structures. Benefitting from 10 years of extensive R&D experience carried out at IPNO, the electromagnetic design studies came out with a solution that fulfills requirements of beam dynamics analysis and manufacturing considerations. Pursuing the same objective, the mechanical design of the cavity and its helium vessel were optimized by performing intensive coupled RF-mechanical simulations. We propose to present a review of the RF and mechanical design studies of the Spoke cavity. We will conclude with the integration of the Spoke cavity with its ancillaries inside the cryomodule.

Slides FRIOC01 [6.321 MB]