| Paper | Title | Other Keywords | Page |
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| MOP014 | Cold Tests of SSR1 Resonators for PXIE | cavity, vacuum, cryomodule, SRF | 112 |
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| Fermilab is currently building the Project X Injector experiment (PXIE). PXIE linac will accelerate 1 mA H− beam up to 30 MeV and serve as a testbed for validation of Project X concepts and mitigation of technical risks. A cryomodule of eight superconducting RF Single Spoke Resonators of type 1 (SSR1) cavities operating at 325 MHz is an integral part of PXIE. Ten SSR1 cavities were manufactured in industry and delivered to Fermilab. In this paper we discuss surface processing and tests of bare SSR1 cavities at the Fermilab Vertical Test Stand (VTS). We report on the measured performance parameters of nine cavities achieved during tests. | |||
| MOP040 | Industrialization of European XFEL Preparation Cycle “Final EP ” at Research Instruments Company | cavity, controls, acceleration, vacuum | 201 |
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In the Specification for XFEL Cavity preparation (R1) two different preparation sequences are presented. Research Instruments Company as one of the two companies contracted for XFEL cavity production and preparation has chosen the so called “final EP” cycle. Major infrastructure components like EP facility and the BCP facility were pre- qualified. This existing and the new set up areas like the cleanroom are distributed over the ground area of the industrial park Bergisch Gladbach. The process flow given in the DESY specification needed adaptation to this scenario. Additional infrastructure beside the once specified needed to be set up to ensure the same quality of processes even with a changed work flow. The general lay out of the facility, matched work flow of preparation and test results of resonators processed by RI company in their infrastructure will be reported.
(R1) Series Surface and acceptance test preparation of superconducting cavities for the European Xfel (XFEL/A - D) JUNE 30, 2009 |
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| MOP043 | ILC-HiGrade Cavities as a Tool of Quality Control for European XFEL | cavity, controls, feedback, framework | 212 |
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Funding: BMBF, Helmholtz Association, ILC-HiGrade, FP7 (CRISP), Alexander von Humboldt Stiftung/Foundation The EXFEL order for SRF cavities includes 24 cavities, which are part of the ILC-HiGrade program. Initially, these cavities serve as quality control (QC) sample extracted from the EXFEL cavities series production on a regular basis. The QC and quality assurance (QA) include all processing steps of the EXFEL cavities. To maximize the information from these so-called QC cavities, a surface mapping technique is applied in a second cold RF test. There the cavities delivered have experienced identical treatment of the inner surface with the exception of mounting of the Helium vessel. After the normal acceptance test at the cavity RF measurement facility, the cavities are removed from the production flow. Further quality assurance steps beginning with a detailed RF test with surface mapping followed by a high resolution optical inspection (OBACHT) are carried out to improve the understanding of defects in close collaboration with the standing experts engaged in the EXFEL production. Results of the first QC cavities tests as well as planned further R&D will be presented and discussed. |
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| MOP054 | Tests of the Accelerating Cryomodules for the European X-Ray Free Electron Laser | cryomodule, cryogenics, cavity, operation | 244 |
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| 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. | |||
| MOP080 | Design of a New Horizontal Test Cryostat for SCRF Cavities at the Uppsala University | cavity, cryomodule, operation, vacuum | 328 |
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| 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. | |||
| MOP090 | Feasibility of Using Conductively Cooled Magnets in Cryomodules of Superconducting Linacs | linac, cryomodule, focusing, solenoid | 361 |
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| While trying to find an optimal way to configure cryomodule for the low energy part of a high-current, high-power superconducting linac, an option of using conductively cooled superconducting focusing lenses was evaluated. As part of this evaluation, several tests were made using existing test cryostat. The cryostat was modified by adding current feed-throughs and two conductively cooled current leads, each equipped with heat sinks at the temperatures of liquid nitrogen and liquid helium. A superconducting magnet was mounted inside the cryostat on an individual heat sink, and thermometers were installed on the leads, heat sinks, and on the magnet’s winding. In this report we provide some details of the heat exchangers’ designs, compare predicted and measured temperature distribution along the leads, and analyze results of the winding temperature measurements. | |||
| TUP048 | Preparations and VT Results of ERL7-cell at Cornell | cavity, cryomodule, vacuum, target | 521 |
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| We have fabricated 7 ERL 7-cell cavities for Cornell ERL project. 4 nu-stiffened and 3-stiffened cavities have been fabricated in house so far. Specification values of our 7-cell is 16.2MV/m with Qo of 2.0·1010 at 1.8K. In this report, we will describe our surface treatments recipe which is based on BCP and the results of vertical tests of these 7-cell cavities. | |||
| TUP088 | NbTiN Based SIS Multilayer Structures for SRF Applications | cavity, SRF, lattice, superconducting-RF | 670 |
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Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. For the past three decades, bulk niobium has been the material of choice for SRF cavities applications. RF cavity performance is now approaching the theoretical limit for bulk niobium. For further improvement of RF cavity performance for future accelerator projects, Superconductor-Insulator-Superconductor (SIS) multilayer structures (as recently proposed by Alex Gurevich) present the theoretical prospect to reach RF performance beyond bulk Nb, using thinly layered higher-Tc superconductors with enhanced Hc1. Jefferson Lab (JLab) is pursuing this approach with the development of NbTiN and AlN based multilayer SIS structures via magnetron sputtering and High Power Impulse Magnetron Sputtering (HiPIMS). This paper presents the results on the characteristics of NbTiN and insulator films and the first RF measurements on NbTiN-based multilayer structure on thick Nb films. |
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| TUP091 | Field Emission Measure During cERL Main Linac Cryomodule High Power Test in KEK | cavity, electron, cryomodule, linac | 678 |
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| A compact Energy Recovery Linac (cERL) is under construction in KEK in order to proof the performance of the key components required for the future ERL project in KEK. The main linac L-band cavities were assembled and tested in the cryomodule under high power operation, during the test information concerning field emission were gathered by means of PIN diodes rings and NaI scintillator located at the cavities ends. The data were analyzed by means of simulations, taking into account the cavities operating conditions and interaction between the accelerated electrons and the cavity surface. The resulting information are used to deduce a possible emitter location, determining if there is any change in the cavities performance with respect to the last vertical test they undertook. With PIN diode is possible to observe the radiation pattern produced by field emission, inferring the meridian where the emitter belongs. On the other hand the bremsstrahlung spectra recorded with the scintillator allow an estimation of the cavity cell where the emitter is located. | |||
| TUP095 | Field Emission and Consequences as Observed and Simulated for CEBAF Upgrade Cryomodules | cavity, neutron, electron, operation | 694 |
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| 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. | |||
| TUP110 | An X-Ray Fluorescence Probe for Defect Detection in Superconducting 1.3 GHz Cavities | cavity, niobium, detector, embedded | 736 |
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| The aim of this project is to develop a system for defect detection by means of X-ray fluorescence (XRF) analysis. XRF is a high sensitivity spectroscopy technique allowing the detection of trace element content, such as the few microgram impurities, responsible for low cavity performances if embedded in the equatorial region during cavity manufacturing. The proposed setup is customized on 1.3 GHz TESLA-type niobium cavities: both the detector and the X-ray excitation source are miniaturized so to allow the probe to enter within the 70 mm iris diameter and aside of the HOM couplers. The detection-excitation geometry is focused on cavity cell equator surface located at about 103 mm from the cavity axis, with an intrinsic spot-size of about 10 mm. The measuring head will be settled on a high angular resolution optical inspection system at DESY, exploiting the experience of OBACHT. Defect position is obtained by means of angular inner cavity surface scanning. A quantitative determination of defect content can also be carried out by means of fundamental parameters technique with a Niobium standard calibration. | |||
| THP024 | Lorentz Force Detuning Simulations of Spoke Cavities With Different Stiffening Elements | cavity, simulation, vacuum, operation | 946 |
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| 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. | |||
| THP049 | SPL RF Coupler Cooling Efficiency | cryomodule, operation, framework, cavity | 1019 |
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| 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. | |||