SRF2013 - List of Keywords (accelerating-gradient)

Paper	Title	Other Keywords	Page
MOP034	The Statistics of Industrial XFEL Cavities Fabrication at E.ZANON	cavity, target, controls, niobium	180
	A. Gresele, M. Giaretta, A. Visentin Ettore Zanon S.p.A., Nuclear Division, Schio, Italy A.A. Sulimov, J.H. Thie DESY, Hamburg, Germany
	Serial production of superconducting cavities for European-XFEL was successfully started at E.ZANON at the end of last year. The production rate (3-4 cavities a week) allows us to summarize the results and present the statistics of industrial cavity fabrication. Many parameters have been traced during different steps of cavity production. The most interesting of them, as cavity length, frequency, field flatness and eccentricity, are presented and discussed. The last results of new preparation cycles development in the frame of E-XFEL projects is also included

TUP065	Chemical Structure of Niobium Samples Vacuum Treated in Nitrogen in Parallel With Very High Q0 Cavities	niobium, cavity, SRF, lattice	583
	Y. Trenikhina IIT, Chicago, USA A. Grassellino, A. Romanenko Fermilab, Batavia, USA
	XPS in combination with subsequent material removal via Ar sputtering as well as XRD are used for the surface analysis and bulk phase characterization of nitrogen treated samples processed parallel with SRF cavities. We investigated the surface chemistry of the samples treated with nitrogen in order to understand this treatment effect on SRF cavity performance for several baking temperatures and durations in order to find cost efficient post-furnace chemistry free procedures to enable high Q-values.

TUP086	Cryogen-Free RF System Studies Using Cryocooler-Cooled Magnesium Diboride-Coated Copper RF Cavities	cavity, niobium, cryomodule, SRF	663
	A. Nassiri, R. Kustom, Th. Proslier ANL, Argonne, USA T. Tan, X. Xi TU, Philadelphia, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06H11357. Studies on the application of magnesium diboride(MgB2)high-Tc superconducting films have shown promise for use with rf cavities. Studies are directed towards applying the films to niobium cavities with the goal to increase accelerating gradients to greater than 50 MeV/m. However, studies also have shown that MgB2 films, with a critical temperature over four times higher than Nb, have surface resistances equal, or nearly equal, at 8-12 K, to what is achieved with niobium at 4 K. It might be possible to design and operate cavity systems in the 8-12K temperature range with cryocoolers that are currently available. The current cryocoolers can remove as much as 20 watts per unit in the range of 8-12K. This suggests that helium-free superconducting RF systems are possible for future light sources and possible industrial and medical linear accelerators. Our current research is directed towards depositing MgB2 films onto copper, or other high thermal conductivity metal, substrates which would allow future cavities to be fabricated as film coated copper structures. We have started atomic layer deposition and Hybrid chemical vapor deposition studies of MgB2 on 2-inch copper coupons.

TUP105	Investigation of the Surface Resistivity of SRF Cavities via the Heat and Srimp Program as Well as the Multi-Cell T-Map System	cavity, SRF, feedback, electron	724
	G.M. Ge, D. Gonnella, G.H. Hoffstaetter, M. Liepe, H. Padamsee Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA F. Furuta Cornell University, Ithaca, New York, USA
	A high-sensitive temperature mapping system for multi-cell SRF cavities has been constructed at Cornell University. The resolution of the system is 1mK. Hence it’s able to detect small temperature increases when cavities reach at low accelerating gradients e.g. 3MV/m. The surface resistivity of superconductor under radio-frequency electromagnetic field can be calculated from the temperature increases. In this contribution, the surface resistance map of multi-cell SRF cavities is shown. The temperature mapping result is possible to establish a relationship between the surface resistivity and the magnetic field as well. Unlike the RF method which is average value of the surface resistance, the T-map results give local surface resistivity versus magnetic field. BCS theory assumes the surface resistivity is independent to the magnetic field. The T-map results, however, suggest that the surface resistance at high-loss region is field dependent and caused Q-slope.

TUP112	Time-Resolved Measurements of High-Field Quench in SRF Cavities	cavity, SRF, niobium, simulation	743
	S. Antipov University of Chicago, Chicago, Illinois, USA E. Efimenko MIPT, Dolgoprudniy, Moscow Region, Russia A. Romanenko, D.A. Sergatskov Fermilab, Batavia, USA
	Fermilab’s temperature mapping system for SRF cavities has been improved to observe quench dynamics with 1ms time resolution. The increase in sampling rate was achieved by localizing the quench and then performing the measurements using a limited subset of thermometers. Implemented experimental procedure allowed to measure temperature distribution within quench spot, as well as the amount of stored energy, at the moment quench starts, during its growth, and decay. For three tested SRF cavities, quenching at fields 21.7 – 33 MeV/m, maximal radius of the normal zone was 40 – 65 mm; time to return to superconducting state: 90 – 250 ms. In the beginning of the process temperature increase rate in the center of the normal zone is as high as 2.5 K/ms, radius increase rate – 20 mm/ms. The described experimental procedure can be useful for investigating how different surface treatments affect the breakdown, understanding of the nature of high-field quench, improvement of quench detection techniques, and material science research for future SRF cavities.

TUP114	XT-map System for Locating SC Cavity Quench Position	cavity, cryogenics, survey, operation	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.

TUP116	Quench field and Location in Vertical Tests at KEK-STF	cavity, linear-collider, linac, cryomodule	751
	Y. Yamamoto, E. Kako, T. Shishido KEK, Ibaraki, Japan
	Many vertical tests have been done for the ILC and ERL at KEK-STF since 2008. T-mapping system (fixed type) was equipped at every vertical test, and quench location was identified completely. Every quench location at quench field will be presented in this paper.

THIOC03	Superconducting Photonic Band Gap Structures for High-Current Applications	cavity, SRF, HOM, wakefield	860
	E.I. Simakov, S. Arsenyev, W.B. Haynes, S.S. Kurennoy, D.Y. Shchegolkov, N.A. Suvorova, T. Tajima LANL, Los Alamos, New Mexico, USA C.H. Boulware, T.L. Grimm Niowave, Inc., Lansing, Michigan, USA
	Funding: This work is supported in parts by the U.S. DOE Early Career Research Program and by the DOD High Energy Laser Joint Technology Office through the Office of Naval Research. We present the results of recent design and testing of several 2.1 GHz superconducting rf (SRF) photonic band gap (PBG) resonators. PBG cells have great potential for outcoupling long-range wakefields in SRF accelerator structures without affecting the fundamental accelerating mode. Using PBG structures in superconducting particle accelerators will allow operation at higher frequencies and moving forward to significantly higher beam luminosities thus leading towards a completely new generation of colliders for high energy physics. Here we report the results of our efforts to fabricate 2.1 GHz PBG cells with round and elliptical rods and to test them with high power at liquid helium temperatures. Two PBG cells with round rods were tested in spring of 2012 and achieved accelerating gradients of 15 MV/m at 2 Kelvin. Two PBG cells with elliptical rods will be tested in summer of 2013.
	Slides THIOC03 [2.284 MB]

THP002	Design of 3-Cell Travelling Wave Cavity for High Gradient Test	cavity, feedback, pick-up, niobium	892
	P.V. Avrakhov, A. Kanareykin, R.A. Kostin, Y. Xie Euclid TechLabs, LLC, Solon, Ohio, USA S. Kazakov, N. Solyak, V.P. Yakovlev Fermilab, Batavia, USA
	Utilization of a superconducting traveling wave accelerating (STWA) structure with small phase advance per cell for future high energy linear colliders may provide accelerating gradient 1.2/1.4 times larger [1] than standing wave structure. However, the STWA structure requires a feedback waveguide [1]. Recent tests of 1.3 GHz model of a single-cell cavity with waveguide feedback demonstrated an accelerating gradient comparable to the gradient in a single-cell ILC-type cavity from the same manufacturer [2]. In the present paper a design for a STWA resonator with a 3-cell accelerating cavity for high gradient tests is considered. Methods to create and support the traveling wave in this structure are discussed. The results of detailed studies of the mechanical and tuning properties of the superconducting resonator with 3-cell traveling wave accelerating structure are also presented.

THP011	Improving Gradient of 9-cell SRF Cavities at Peking University	cavity, SRF, niobium, electron	914
	J.K. Hao, J.E. Chen, L. Lin, K.X. Liu, X.Y. Lu, S.W. Quan, F. Wang, H.M. Xie, B.C. Zhang, K. Zhao, F. Zhu PKU, Beijing, People's Republic of China
	Four 9-cell TESLA superconducting cavities have been fabricated with Ningxia OTIC niobium material, including two fine grain and two large grain niobium cavities. The cavities have been tested after post treatments. At the early stage (PKU1 and PKU2), the gradient was about 23 MV/m. The gradient of PKU3 reached 28.4 MV/m, but the Q is low. The newest large grain 1.3 GHz 9-cell TESLA type SRF cavity (PKU4) has been made with careful control of machining, and improved surface treatment and electron beam welding. The maximum of gradient is 32.4 MV/m and the intrinsic quality factor (Q0) is 1.3x10¹⁰, which meet the requirement for ILC both in accelerating gradient and intrinsic quality factor.

THP022	DEVELOPMENT OF A VERY LOW BETA SUPERCONDUCTING SINGLE SPOKE CAVITY FOR CHINA-ADS LINAC*	cavity, linac, LLRF, niobium	942
	H. Li, J.P. Dai, L.H. Li, H.Y. Lin, Q. Ma, W.M. Pan, Y. Sun, Q.Y. Wang, J. Zhang IHEP, Beijing, People's Republic of China H. Huang, P. Sha Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China
	Twelve very low Beta superconducting single spoke cavities whose Beta is only 0.12 (Spoke012) operating at 325MHz, are adopted in Injector I for China-ADS linac. This type of spoke cavity is believed to be one of the key challenges for its very low geometric Beta. So far, collaborated with Peking University and Harbin Institute of Technology, IHEP has designed, fabricated and tested the spoke012 prototype cavity successfully. This paper presents the details of the design, fabrication and vertical test results for Spoke012 prototype cavity.

THP030	Superconducting RF Cavity Development With UK Industry	cavity, SRF, multipactoring, niobium	966
	A.E. Wheelhouse, R.K. Buckley, L.S. Cowie, P. Goudket, A.R. Goulden, P.A. McIntosh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom C.A. Cooper, C.M. Ginsburg, A. Grassellino, O.S. Melnychuk, A.M. Rowe, D.A. Sergatskov Fermilab, Batavia, USA J.R. Everard, N. Shakespeare Shakespeare Engineering, South Woodham Ferrers, Essex, United Kingdom
	As part of a continuing STFC Innovations Partnership Scheme (IPS) grant, in support of enabling UK industry to address the large potential market for superconducting RF structures Daresbury Laboratory and Shakespeare Engineering Ltd are developing the capability to fabricate, process and test a niobium 9-cell 1.3 GHz superconducting RF cavity. A single-cell cavity fabricated under this grant was surface processed and tested at Fermilab, and achieved an accelerating gradient in excess of 40 MV/m at an unloaded quality factor in excess of 1.0 x 10¹⁰. This paper presents the results of the single-cell cavity testing and discusses the progress made to date in the development of the design and manufacture of a 9-cell niobium cavity, which Shakespeare Engineering Ltd will fabricate and which is anticipated to be qualified in 2014.

Paper

Title

Other Keywords

Page

MOP034

The Statistics of Industrial XFEL Cavities Fabrication at E.ZANON

cavity, target, controls, niobium

180

A. Gresele, M. Giaretta, A. Visentin
Ettore Zanon S.p.A., Nuclear Division, Schio, Italy
A.A. Sulimov, J.H. Thie
DESY, Hamburg, Germany

Serial production of superconducting cavities for European-XFEL was successfully started at E.ZANON at the end of last year. The production rate (3-4 cavities a week) allows us to summarize the results and present the statistics of industrial cavity fabrication. Many parameters have been traced during different steps of cavity production. The most interesting of them, as cavity length, frequency, field flatness and eccentricity, are presented and discussed. The last results of new preparation cycles development in the frame of E-XFEL projects is also included

TUP065

Chemical Structure of Niobium Samples Vacuum Treated in Nitrogen in Parallel With Very High Q0 Cavities

niobium, cavity, SRF, lattice

583

Y. Trenikhina
IIT, Chicago, USA
A. Grassellino, A. Romanenko
Fermilab, Batavia, USA

XPS in combination with subsequent material removal via Ar sputtering as well as XRD are used for the surface analysis and bulk phase characterization of nitrogen treated samples processed parallel with SRF cavities. We investigated the surface chemistry of the samples treated with nitrogen in order to understand this treatment effect on SRF cavity performance for several baking temperatures and durations in order to find cost efficient post-furnace chemistry free procedures to enable high Q-values.

TUP086

Cryogen-Free RF System Studies Using Cryocooler-Cooled Magnesium Diboride-Coated Copper RF Cavities

cavity, niobium, cryomodule, SRF

663

A. Nassiri, R. Kustom, Th. Proslier
ANL, Argonne, USA
T. Tan, X. Xi
TU, Philadelphia, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06H11357.
Studies on the application of magnesium diboride(MgB2)high-Tc superconducting films have shown promise for use with rf cavities. Studies are directed towards applying the films to niobium cavities with the goal to increase accelerating gradients to greater than 50 MeV/m. However, studies also have shown that MgB2 films, with a critical temperature over four times higher than Nb, have surface resistances equal, or nearly equal, at 8-12 K, to what is achieved with niobium at 4 K. It might be possible to design and operate cavity systems in the 8-12K temperature range with cryocoolers that are currently available. The current cryocoolers can remove as much as 20 watts per unit in the range of 8-12K. This suggests that helium-free superconducting RF systems are possible for future light sources and possible industrial and medical linear accelerators. Our current research is directed towards depositing MgB2 films onto copper, or other high thermal conductivity metal, substrates which would allow future cavities to be fabricated as film coated copper structures. We have started atomic layer deposition and Hybrid chemical vapor deposition studies of MgB2 on 2-inch copper coupons.

TUP105

Investigation of the Surface Resistivity of SRF Cavities via the Heat and Srimp Program as Well as the Multi-Cell T-Map System

cavity, SRF, feedback, electron

724

G.M. Ge, D. Gonnella, G.H. Hoffstaetter, M. Liepe, H. Padamsee
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
F. Furuta
Cornell University, Ithaca, New York, USA

A high-sensitive temperature mapping system for multi-cell SRF cavities has been constructed at Cornell University. The resolution of the system is 1mK. Hence it’s able to detect small temperature increases when cavities reach at low accelerating gradients e.g. 3MV/m. The surface resistivity of superconductor under radio-frequency electromagnetic field can be calculated from the temperature increases. In this contribution, the surface resistance map of multi-cell SRF cavities is shown. The temperature mapping result is possible to establish a relationship between the surface resistivity and the magnetic field as well. Unlike the RF method which is average value of the surface resistance, the T-map results give local surface resistivity versus magnetic field. BCS theory assumes the surface resistivity is independent to the magnetic field. The T-map results, however, suggest that the surface resistance at high-loss region is field dependent and caused Q-slope.

TUP112

Time-Resolved Measurements of High-Field Quench in SRF Cavities

cavity, SRF, niobium, simulation

743

S. Antipov
University of Chicago, Chicago, Illinois, USA
E. Efimenko
MIPT, Dolgoprudniy, Moscow Region, Russia
A. Romanenko, D.A. Sergatskov
Fermilab, Batavia, USA

Fermilab’s temperature mapping system for SRF cavities has been improved to observe quench dynamics with 1ms time resolution. The increase in sampling rate was achieved by localizing the quench and then performing the measurements using a limited subset of thermometers. Implemented experimental procedure allowed to measure temperature distribution within quench spot, as well as the amount of stored energy, at the moment quench starts, during its growth, and decay. For three tested SRF cavities, quenching at fields 21.7 – 33 MeV/m, maximal radius of the normal zone was 40 – 65 mm; time to return to superconducting state: 90 – 250 ms. In the beginning of the process temperature increase rate in the center of the normal zone is as high as 2.5 K/ms, radius increase rate – 20 mm/ms. The described experimental procedure can be useful for investigating how different surface treatments affect the breakdown, understanding of the nature of high-field quench, improvement of quench detection techniques, and material science research for future SRF cavities.

TUP114

XT-map System for Locating SC Cavity Quench Position

cavity, cryogenics, survey, operation

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.

TUP116

Quench field and Location in Vertical Tests at KEK-STF

cavity, linear-collider, linac, cryomodule

751

Y. Yamamoto, E. Kako, T. Shishido
KEK, Ibaraki, Japan

Many vertical tests have been done for the ILC and ERL at KEK-STF since 2008. T-mapping system (fixed type) was equipped at every vertical test, and quench location was identified completely. Every quench location at quench field will be presented in this paper.

THIOC03

Superconducting Photonic Band Gap Structures for High-Current Applications

cavity, SRF, HOM, wakefield

860

E.I. Simakov, S. Arsenyev, W.B. Haynes, S.S. Kurennoy, D.Y. Shchegolkov, N.A. Suvorova, T. Tajima
LANL, Los Alamos, New Mexico, USA
C.H. Boulware, T.L. Grimm
Niowave, Inc., Lansing, Michigan, USA

Funding: This work is supported in parts by the U.S. DOE Early Career Research Program and by the DOD High Energy Laser Joint Technology Office through the Office of Naval Research.
We present the results of recent design and testing of several 2.1 GHz superconducting rf (SRF) photonic band gap (PBG) resonators. PBG cells have great potential for outcoupling long-range wakefields in SRF accelerator structures without affecting the fundamental accelerating mode. Using PBG structures in superconducting particle accelerators will allow operation at higher frequencies and moving forward to significantly higher beam luminosities thus leading towards a completely new generation of colliders for high energy physics. Here we report the results of our efforts to fabricate 2.1 GHz PBG cells with round and elliptical rods and to test them with high power at liquid helium temperatures. Two PBG cells with round rods were tested in spring of 2012 and achieved accelerating gradients of 15 MV/m at 2 Kelvin. Two PBG cells with elliptical rods will be tested in summer of 2013.

Slides THIOC03 [2.284 MB]

THP002

Design of 3-Cell Travelling Wave Cavity for High Gradient Test

cavity, feedback, pick-up, niobium

892

P.V. Avrakhov, A. Kanareykin, R.A. Kostin, Y. Xie
Euclid TechLabs, LLC, Solon, Ohio, USA
S. Kazakov, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA

Utilization of a superconducting traveling wave accelerating (STWA) structure with small phase advance per cell for future high energy linear colliders may provide accelerating gradient 1.2/1.4 times larger [1] than standing wave structure. However, the STWA structure requires a feedback waveguide [1]. Recent tests of 1.3 GHz model of a single-cell cavity with waveguide feedback demonstrated an accelerating gradient comparable to the gradient in a single-cell ILC-type cavity from the same manufacturer [2]. In the present paper a design for a STWA resonator with a 3-cell accelerating cavity for high gradient tests is considered. Methods to create and support the traveling wave in this structure are discussed. The results of detailed studies of the mechanical and tuning properties of the superconducting resonator with 3-cell traveling wave accelerating structure are also presented.

THP011

Improving Gradient of 9-cell SRF Cavities at Peking University

cavity, SRF, niobium, electron

914

J.K. Hao, J.E. Chen, L. Lin, K.X. Liu, X.Y. Lu, S.W. Quan, F. Wang, H.M. Xie, B.C. Zhang, K. Zhao, F. Zhu
PKU, Beijing, People's Republic of China

Four 9-cell TESLA superconducting cavities have been fabricated with Ningxia OTIC niobium material, including two fine grain and two large grain niobium cavities. The cavities have been tested after post treatments. At the early stage (PKU1 and PKU2), the gradient was about 23 MV/m. The gradient of PKU3 reached 28.4 MV/m, but the Q is low. The newest large grain 1.3 GHz 9-cell TESLA type SRF cavity (PKU4) has been made with careful control of machining, and improved surface treatment and electron beam welding. The maximum of gradient is 32.4 MV/m and the intrinsic quality factor (Q0) is 1.3x10¹⁰, which meet the requirement for ILC both in accelerating gradient and intrinsic quality factor.

THP022

DEVELOPMENT OF A VERY LOW BETA SUPERCONDUCTING SINGLE SPOKE CAVITY FOR CHINA-ADS LINAC*

cavity, linac, LLRF, niobium

942

H. Li, J.P. Dai, L.H. Li, H.Y. Lin, Q. Ma, W.M. Pan, Y. Sun, Q.Y. Wang, J. Zhang
IHEP, Beijing, People's Republic of China
H. Huang, P. Sha
Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China

Twelve very low Beta superconducting single spoke cavities whose Beta is only 0.12 (Spoke012) operating at 325MHz, are adopted in Injector I for China-ADS linac. This type of spoke cavity is believed to be one of the key challenges for its very low geometric Beta. So far, collaborated with Peking University and Harbin Institute of Technology, IHEP has designed, fabricated and tested the spoke012 prototype cavity successfully. This paper presents the details of the design, fabrication and vertical test results for Spoke012 prototype cavity.

THP030

Superconducting RF Cavity Development With UK Industry

cavity, SRF, multipactoring, niobium

966

A.E. Wheelhouse, R.K. Buckley, L.S. Cowie, P. Goudket, A.R. Goulden, P.A. McIntosh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
C.A. Cooper, C.M. Ginsburg, A. Grassellino, O.S. Melnychuk, A.M. Rowe, D.A. Sergatskov
Fermilab, Batavia, USA
J.R. Everard, N. Shakespeare
Shakespeare Engineering, South Woodham Ferrers, Essex, United Kingdom

As part of a continuing STFC Innovations Partnership Scheme (IPS) grant, in support of enabling UK industry to address the large potential market for superconducting RF structures Daresbury Laboratory and Shakespeare Engineering Ltd are developing the capability to fabricate, process and test a niobium 9-cell 1.3 GHz superconducting RF cavity. A single-cell cavity fabricated under this grant was surface processed and tested at Fermilab, and achieved an accelerating gradient in excess of 40 MV/m at an unloaded quality factor in excess of 1.0 x 10¹⁰. This paper presents the results of the single-cell cavity testing and discusses the progress made to date in the development of the design and manufacture of a 9-cell niobium cavity, which Shakespeare Engineering Ltd will fabricate and which is anticipated to be qualified in 2014.