03 Technology
3A Superconducting RF

Paper	Title	Page
SUPB025	Development of Superconducting Radio-Frequency (SRF) Deflecting Mode Cavities and Associated Waveguide Dampers for the APS Upgrade Short Pulse X-Ray Project	65
	J.P. Holzbauer, A. Nassiri, G.J. Waldschmidt, G. Wu ANL, Argonne, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CHI1357. The Advanced Photon Source Upgrade (APS-U) is a Department of Energy (DoE) funded project to increase the available x-ray beam brightness and add capability to enhance time-resolved experiments on few-ps-scale at APS. A centerpiece of the upgrade is the generation of short pulse x-rays (SPXs) for pump-probe time-resolved capability using SRF deflecting cavities[1]. The SPX project is designed to produce 1-2 ps x-ray pulses for some users compared to the standard 100 ps pulses currently produced. SPX calls for using superconducting rf (SRF) deflecting cavities to give the electrons a correlation between longitudinal position in the bunch and vertical momentum [2]. The light produced by this bunch can be passed through a slit to produce a pulse of light much shorter than the bunch length at reduced flux. The ongoing work of designing these cavities and associated technologies will be presented. This includes the design and prototyping of higher-order (HOM) and lower-order mode (LOM) couplers and dampers as well as the fundamental power coupler (FPC). This work will be given in the context of SPX0, a demonstration cryomodule with two deflecting cavities to be installed in APS in early 2014. [1] A. Zholents, et al., NIM A 425, 385 (1999) [2] A. Nassiri, et al., “ Status of the Short-Pulse X-Ray Project at the Advanced Photon Source,” IPAC 2012, New Orleans, LA, May 2012.
SUPB026	Multipacting Analysis of High-velocity Superconducting Spoke Resonators	68
	C.S. Hopper, J.R. Delayen ODU, Norfolk, Virginia, USA
	Some of the advantages of superconducting spoke cavities are currently being investigated for the high-velocity regime. When determining a final, optimized geometry, one must consider the possible limiting effects multipacting could have on the cavity. We report on the results of analytical calculations and numerical simulations of multipacting electrons in superconducting spoke cavities and methods for reducing their impact.
SUPB027	Mechanical Study of the First Superconducting Half-wave Resonator for Injector II of CADS Project	71
	S. He, Y. He, S.C. Huang, F.F. Wang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	Funding: This work is Supported by the National Natural Science Foundation of China (Grant Agreement 91026001) Within the framework of the China Accelerator-Driven Sub-critical Systems (CADS) project, Institute of Modern Physics (IMP) Chinese Academic of Sciences has proposed a 162.5 MHz Half-Wave Resonator (HWR) Superconducting cavity for low energy section (β=0.09) of high power proton linear accelerators as a new injector II for CIADS. For the geometrical design of superconducting cavities structure mechanical simulations are essential to predict mechanical eigenmodes and the deformation of the cavity walls due to bath pressure effects and the cavity cool-down. Additionally, the tuning analysis has been investigated to control the frequency against microphonics and Lorentz force detuning. Therefore, several RF, static structure, thermal and modal analysis with a three-dimensional Finite-Element Method (FEM) code Traditional ANSYS have been performed.
SUPB028	The Superconducting CH Cavity Development in IMP*	74
	M.X. Xu, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, Z.J. Wang, J.W. Xia, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	Funding: Work supported by 91026001 Nature Science Foundation of China The Cross-Bar H-type (CH) cavity is a multi-gap drift tube structure operated in the H21 mode [1]. The Institute of Modern Physics (IMP) has been doing research and development on this type of superconducting CH cavity which can work at the C-ADS (accelerator driver sub-critical system of China). A new geometry CH cavity has been proposed which have smaller radius. It’s suitable in fabrication, and it’s can reduce cost too .Detailed numerical simulations with CST MicroWave Studio have been performed. An overall surface reduction of 30% against the old structure seems feasible. A copper model CH cavity is being fabrication for validating the simulations and the procedure of fabricating niobium cavity.
SUPB029	Impact of Trapped Flux and Systematic Flux Expulsion in Superconducting Niobium	77
	J.M. Vogt, J. Knobloch, O. Kugeler HZB, Berlin, Germany
	The intrinsic quality factor Q0 of superconducting cavities is known to depend on various factors like niobium material properties, treatment history and magnetic shielding. We already reported an additional impact of temperature gradients during the cool-down on the obtained Q0. We believe cooling conditions can influence the level of flux trapping and hence the residual resistance. For further studies we have constructed a test stand using niobium rods to study flux trapping. Here we can precisely control the temperature and approach Tc in the superconducting state. Although the sample remains in the superconducting state a change in the amount of trapped flux is visible. The procedure can be applied repeatedly resulting in a significantly lowered level of trapped flux in the sample. Applying a similar procedure to a superconducting cavity could allow for reduction of the magnetic contribution to the surface resistance and result in a significant improvement of Q0.
SUPB039	Compact Superconducting Crabbing and Deflecting Cavities	95
	S.U. De Silva ODU, Norfolk, Virginia, USA S.U. De Silva JLAB, Newport News, Virginia, USA
	Recently, new geometries for superconducting crabbing and deflecting cavities have been developed that have significantly improved properties over those the standard TM110 cavities. They are smaller, have low surface fields, high shunt impedance and, more importantly for some of them, no lower-order-mode with a well-separated fundamental mode. This talk will present the status of the development of these cavities.
MO1A03	SRF Linac Technology Development at Fermilab	110
	V.P. Yakovlev, C.M. Ginsburg Fermilab, Batavia, USA
	Superconducting linear accelerators are developing for different applications – for fundamental researches in High-Energy and High – Intensity Frontiers, nuclear physics, energetics, neutron spallation sources, synchrotron radiation sources, etc. The linac applications dictate the requirements for superconducting acceleration system, and, thus, for SRF technology. Fermilab is currently involved in two projects: ILC and Project X, both are based on SRF technology. For High-Intensity Frontier investigations, the Project X – a multi-experiment facility is developing based on 3 GeV, CW H− linac in the frame of a wide collaboration of US National Laboratories. In a CW H− linac several families of SC cavities are used: half-wave resonators (162.5 MHz); single-spoke cavities, SSR1 and SSR2 (325 MHz); elliptical 5-cell β=0.6 and β=0.9 cavities (650 MHz). Pulsed 3-8 GeV linac and ILC linac are based on 9-cell 1.3 GHz cavities. In the paper the basic requirements and the status of development of SC accelerating cavities, auxiliaries (couplers, tuners, etc.) and cryomodules are presented as well as technology challenges caused by their specifics.
	Slides MO1A03 [3.551 MB]
MOPLB06	Fermilab 1.3 GHz Superconducting RF Cavity and Cryomodule Program for Future Linacs	153
	C.M. Ginsburg Fermilab, Batavia, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The proposed Project X accelerator and the International Linear Collider are based on superconducting RF technology. As a critical part of this effort, Fermilab has developed an extensive program in 1.3 GHz SRF cavity and cryomodule development. This program includes cavity inspection, surface processing, clean assembly, low-power bare cavity tests and pulsed high-power dressed cavity tests. Well performing cavities have been assembled into cryomodules for pulsed high-power tests and will be tested with beam. In addition, peripheral hardware such as tuners and couplers are under development. The current status and accomplishments of the Fermilab 1.3 GHz activity will be described, as well as the R&D program to extend the existing SRF pulsed operational experience into the CW regime.
	Slides MOPLB06 [1.508 MB]
MOPLB07	Non-destructive Inspections for SC Cavities	156
	Y. Iwashita, Y. Fuwa, M. Hashida, K. Otani, S. Sakabe, S. Tokita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan H. Hayano, K. Watanabe, Y. Yamamoto KEK, Ibaraki, Japan
	Non-destructive Inspections play important roles to improve yield in production of high-performance SC Cavities. Starting from the high-resolution camera for inspection of the cavity inner surface, high resolution T-map, X-map and eddy current scanner have been developed. We are also investigating radiography to detect small voids inside the Nb EBW seam, where the target resolution is 0.1 mm. We are carrying out radiography tests with X-rays induced from an ultra short pulse intense laser. Recent progress will be presented.
	Slides MOPLB07 [5.810 MB]
MOPB052	Fermilab 1.3 GHz Superconducting RF Cavity and Cryomodule Program for Future Linacs	291
	C.M. Ginsburg Fermilab, Batavia, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The proposed Project X accelerator and the International Linear Collider are based on superconducting RF technology. As a critical part of this effort, Fermilab has developed an extensive program in 1.3 GHz SRF cavity and cryomodule development. This program includes cavity inspection, surface processing, clean assembly, low-power bare cavity tests and pulsed high-power dressed cavity tests. Well performing cavities have been assembled into cryomodules for pulsed high-power tests and will be tested with beam. In addition, peripheral hardware such as tuners and couplers are under development. The current status and accomplishments of the Fermilab 1.3 GHz activity will be described, as well as the R&D program to extend the existing SRF pulsed operational experience into the CW regime.
MOPB053	Non-destructive Inspections for SC Cavities	294
	Y. Iwashita, Y. Fuwa, M. Hashida, K. Otani, S. Sakabe, S. Tokita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan H. Hayano, K. Watanabe, Y. Yamamoto KEK, Ibaraki, Japan
	Non-destructive Inspections play important roles to improve yield in production of high-performance SC Cavities. Starting from the high-resolution camera for inspection of the cavity inner surface, high resolution T-map, X-map and eddy current scanner have been developed. We are also investigating radiography to detect small voids inside the Nb EBW seam, where the target resolution is 0.1 mm. We are carrying out radiography tests with X-rays induced from an ultra short pulse intense laser. Recent progress will be presented.
MOPB054	Test Results of Tesla-style Cryomodules at Fermilab	297
	E.R. Harms, K. Carlson, B. Chase, D.J. Crawford, E. Cullerton, D.R. Edstrom, Jr, A. Hocker, M.J. Kucera, J.R. Leibfritz, O.A. Nezhevenko, D.J. Nicklaus, Y.M. Pischalnikov, P.S. Prieto, J. Reid, W. Schappert, P. Varghese Fermilab, Batavia, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. Commissioning and operation of the first Tesla-style Cryomodule (CM-1) at Fermilab was concluded in recent months. It has now been replaced by a second Tesla Type III+ module, RFCA002. It is the first 8-cavity ILC style cryomodule to be built at Fermilab and also the first accelerating cryomodule of the Advanced Superconducting Test Accelerator (ASTA). We report on the operating results of both of these cryomodules.
MOPB055	Development of Superconducting Radio-Frequency (SRF) Deflecting Mode Cavities and Associated Waveguide Dampers for the APS Upgrade Short Pulse X-Ray Project	300
	J.P. Holzbauer, A. Nassiri, G.J. Waldschmidt, G. Wu ANL, Argonne, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CHI1357. The Advanced Photon Source Upgrade (APS-U) is a Department of Energy (DoE) funded project to increase the available x-ray beam brightness and add capability to enhance time-resolved experiments on few-ps-scale at APS. A centerpiece of the upgrade is the generation of short pulse x-rays (SPXs) for pump-probe time-resolved capability using SRF deflecting cavities[1]. The SPX project is designed to produce 1-2 ps x-ray pulses for some users compared to the standard 100 ps pulses currently produced. SPX calls for using superconducting rf (SRF) deflecting cavities to give the electrons a correlation between longitudinal position in the bunch and vertical momentum [2]. The light produced by this bunch can be passed through a slit to produce a pulse of light much shorter than the bunch length at reduced flux. The ongoing work of designing these cavities and associated technologies will be presented. This includes the design and prototyping of higher-order (HOM) and lower-order mode (LOM) couplers and dampers as well as the fundamental power coupler (FPC). This work will be given in the context of SPX0, a demonstration cryomodule with two deflecting cavities to be installed in APS in early 2014. [1] A. Zholents, et al., NIM A 425, 385 (1999) [2] A. Nassiri, et al., “ Status of the Short-Pulse X-Ray Project at the Advanced Photon Source,” IPAC 2012, New Orleans, LA, May 2012.
MOPB056	Multipacting Analysis of High-Velocity Superconducting Spoke Resonators	303
	C.S. Hopper, J.R. Delayen ODU, Norfolk, Virginia, USA
	Some of the advantages of superconducting spoke cavities are currently being investigated for the high-velocity regime. When determining a final, optimized geometry, one must consider the possible limiting effects multipacting could have on the cavity. We report on the results of analytical calculations and numerical simulations of multipacting electrons in superconducting spoke cavities and methods for reducing their impact.
MOPB057	Mechanical Study of the First Superconducting Half-wave Resonator for Injector II of CADS Project	306
	S. He, Y. He, S.C. Huang, F.F. Wang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	Funding: This work is Supported by the National Natural Science Foundation of China (Grant Agreement 91026001) Within the framework of the China Accelerator-Driven Sub-critical Systems (CADS) project, Institute of Modern Physics (IMP) Chinese Academic of Sciences has proposed a 162.5 MHz Half-Wave Resonator (HWR) Superconducting cavity for low energy section (β=0.09) of high power proton linear accelerators as a new injector II for CIADS. For the geometrical design of superconducting cavities structure mechanical simulations are essential to predict mechanical eigenmodes and the deformation of the cavity walls due to bath pressure effects and the cavity cool-down. Additionally, the tuning analysis has been investigated to control the frequency against microphonics and Lorentz force detuning. Therefore, several RF, static structure, thermal and modal analysis with a three-dimensional Finite-Element Method (FEM) code Traditional ANSYS have been performed.
MOPB059	The Superconducting CH Cavity Development in IMP*	309
	M.X. Xu, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, Z.J. Wang, J.W. Xia, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	Funding: Work supported by 91026001 Nature Science Foundation of China The Cross-Bar H-type (CH) cavity is a multi-gap drift tube structure operated in the H21 mode [1]. The Institute of Modern Physics (IMP) has been doing research and development on this type of superconducting CH cavity which can work at the C-ADS (accelerator driver sub-critical system of China). A new geometry CH cavity has been proposed which have smaller radius. It’s suitable in fabrication, and it’s can reduce cost too .Detailed numerical simulations with CST MicroWave Studio have been performed. An overall surface reduction of 30% against the old structure seems feasible. A copper model CH cavity is being fabrication for validating the simulations and the procedure of fabricating niobium cavity.
MOPB060	RF Surface Impedance Characterization of Potential New Materials for SRF-based Accelerators	312
	B. P. Xiao, G.V. Eremeev, H.L. Phillips, C.E. Reece JLAB, Newport News, Virginia, USA M.J. Kelley, B. P. Xiao The College of William and Mary, Williamsburg, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. In the development of new superconducting materials for possible use in SRF-based accelerators, it is useful to work with small candidate samples rather than complete resonant cavities. The recently commissioned Jefferson Lab rf Surface Impedance Characterization (SIC) system* can presently characterize the central region of 50 mm diameter disk samples of various materials from 2 to 40 K exposed to RF magnetic fields up to 14 mT at 7.4 GHz. We report the measurement results from bulk Nb, thin film Nb on Cu and sapphire substrates, and thin film MgB2 on sapphire substrate provided by colleagues at JLab and Temple University. We also report on efforts to extend the operating range to higher fields. * B.P. Xiao, et al., RSI, 2011. 82: p. 056104
MOPB061	The New 2nd Generation SRF R&D Facility at Jefferson Lab: TEDF	315
	C.E. Reece, A.V. Reilly JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The US Department of Energy has funded a near-complete renovation of the SRF-based accelerator research and development facilities at Jefferson Lab. The project to accomplish this, the Technical and Engineering Development Facility (TEDF) Project has completed the first of two phases. An entirely new 3,300 m2 purpose-built SRF technical work facility has been constructed and is being occupied in summer of 2012. All SRF work processes with the exception of cryogenic testing has been relocated into the new building. All cavity fabrication, processing, thermal treatment, chemistry, cleaning, and assembly work is collected conveniently into a new LEED-certified building. An innovatively designed 750 m2 cleanroom/chemrooms suite provides long-term flexibility for support of multiple R&D and construction projects as well as continued process evolution. The detailed characteristics of this perhaps first 2nd-generation SRF facility will be described.
MOPB062	A New Internal Optical Profilometry System for Characterization of RF Cavity Surfaces – CYCLOPS	318
	C.E. Reece, A.D. Palczewski, H. Tian JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Jefferson Lab has received and commissioned a new interferometric optical profilometer specifically designed to provide internal surface mapping of elliptical rf cavities. The CavitY CaLibrated Optical Profilometry System – CYCLOPS – provides better than 2 micron lateral resolution and 0.1 micron surface height resolution of programmatically selected locations on the interior surface of multi-cell cavities. The system is being used to provide detailed characterization of surface topographic evolution as a function of applied surface treatments and to investigate particular localized defects. We also intend to use the system for 3D mapping of actual interior rf surface geometry for feedback to structure design model and fabrication tooling. First uses will be illustrated. CYCLOPS was developed and fabricated by MicroDynamics Inc., Woodstock, GA, USA.
MOPB063	Superconducting RF Linac for eRHIC	321
	S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, H. Hahn, D. Kayran, V. Litvinenko, G.J. Mahler, G.T. McIntyre, V. Ptitsyn, R. Than, J.E. Tuozzolo, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA S.A. Belomestnykh Stony Brook University, Stony Brook, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE. eRHIC will collide high-intensity hadron beams from RHIC with 50-mA electron beam from a six-pass 30-GeV Energy Recovery Linac (ERL), which will utilize 704 MHz superconducting RF accelerating structures. This presentation describes the eRHIC SRF linac requirements, layout and parameters, 5-cell SRF cavity with a new HOM damping scheme, project status and plans.
MOPB064	Developing of Superconducting RF Guns at BNL	324
	S.A. Belomestnykh, Z. Altinbas, I. Ben-Zvi, J.C. Brutus, D.M. Gassner, H. Hahn, L.R. Hammons, J.P. Jamilkowski, D. Kayran, J. Kewisch, V. Litvinenko, G.J. Mahler, G.T. McIntyre, D. Pate, D. Phillips, T. Rao, S.K. Seberg, T. Seda, B. Sheehy, J. Skaritka, K.S. Smith, R. Than, J.E. Tuozzolo, E. Wang, Q. Wu, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, J. Dai, M. Ruiz-Osés, T. Xin Stony Brook University, Stony Brook, USA C.H. Boulware, T.L. Grimm Niowave, Inc., Lansing, Michigan, USA A. Burrill JLAB, Newport News, Virginia, USA R. Calaga CERN, Geneva, Switzerland M.D. Cole, A.J. Favale, D. Holmes, J. Rathke, T. Schultheiss, A.M.M. Todd AES, Medford, NY, USA X. Liang SBU, Stony Brook, New York, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. The work at Niowave is supported by the US DOE under SBIR contract No. DE-FG02-07ER84861. BNL is developing several superconducting RF guns for different applications. The first gun is based on a half-cell 1.3 GHz elliptical cavity. This gun is used to study generation of polarized electrons from GaAs photocathodes. The second gun, also of a half-cell elliptical cavity design, operates at 704 MHz and is designed to produce high average current electron beam for the ERL prototype from a multi-alkali photocathodes. The third gun is of a quarter-wave resonator type, operating at 112 MHz. This gun will be used for photocathode studies, including a diamond-amplified cathode, and to generate high charge, low repetition rate beam for the coherent electron cooling experiment. In this presentation we will briefly describe the gun designs, present recent test results and discuss future plans.
MOPB065	Impact of Trapped Magnetic Flux and Systematic Flux Expulsion in Superconducting Niobium	327
	J.M. Vogt, J. Knobloch, O. Kugeler HZB, Berlin, Germany
	The intrinsic quality factor Q0 of superconducting cavities is known to depend on various factors like niobium material properties, treatment history and magnetic shielding. We already reported an additional impact of temperature gradients during the cool-down on the obtained Q0. We believe cooling conditions can influence the level of flux trapping and hence the residual resistance. For further studies we have constructed a test stand using niobium rods to study flux trapping. Here we can precisely control the temperature and approach Tc in the superconducting state. Although the sample remains in the superconducting state a change in the amount of trapped flux is visible. The procedure can be applied repeatedly resulting in a significantly lowered level of trapped flux in the sample. Applying a similar procedure to a superconducting cavity could allow for reduction of the magnetic contribution to the surface resistance and result in a significant improvement of Q0.
MOPB066	Alternative Approaches for HOM-Damped Cavities	330
	B. Riemann, T. Weis DELTA, Dortmund, Germany A. Neumann HZB, Berlin, Germany
	Funding: this work is partly funded by BMBF contract no. 05K10PEA Elliptical cavities have been a standard in SRF linac technology for 30 years. We present another approach to base cell geometry based on Bezier splines, that leads to equal performance levels and is much more flexible in terms of optimization. Using the BERLinPro main linac as an example, a spline multicell cavity is designed with equal performance goals. For the damping of higher order modes (HOMs), the installation of waveguides at the ends of a multicell cavity is a common approach.
MOPB067	Results and Performance Simulations of the Main Linac Design for BERLinPro	333
	A. Neumann, W. Anders, J. Knobloch HZB, Berlin, Germany K. Brackebusch, T. Flisgen, T. Galek, K. Papke, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany B. Riemann, T. Weis DELTA, Dortmund, Germany
	Funding: this work is partly funded by BMBF contract no. 05K10PEA and 05K10HRC The Berlin Energy Recovery Linac Project (BERLinPro) is designed to develop and demonstrate CW LINAC technology for 100-mA-class ERLs. High-current operation requires an effective damping of higher-order modes (HOMs) of the 1.3 GHz main-linac cavities. We have studied elliptical 7-cell cavities damped by on the whole five waveguides at both ends. Eigenmode computations for geometrical figures of merit show that the present design should allow successful CW linac operation at the maximum beam current of 100 mA/77 pC bunch charge. To verify the results, the external Q factors are compared to the results of S-Parameter simulations that are postprocessed by a pole-fitting technique. First results of scattering parameter measurement on a room-temperature aluminium model are discussed. An outlook presenting the possibilities of combined multi-cavity simulations is included.
MOPB069	Study of HPR Created Oxide Layer at Nb Surfaces	336
	P.V. Tyagi Sokendai, Ibaraki, Japan H. Hayano, S. Kato, T. Saeki, M. Sawabe KEK, Ibaraki, Japan
	The performance of superconducting radio frequency (SRF) niobium (Nb) cavities strongly depends on final surface condition. Therefore the surface preparation of these SRF cavities often becomes critical. The preparation of surface includes two steps; surface chemistry (in order to get a smooth surface) and cleaning/rinsing (in order to remove contaminants left after the surface chemistry). As high pressure rinsing (HPR) with ultra pure water (UPW) is most commonly used surface cleaning method after the surface chemistry, it's very interesting to characterize the Nb surfaces after HPR. Results of our surface characterization done by XPS (x-ray photoelectron spectroscopy) with depth profiling show the presence of a thicker oxide surface characterization results show the presence of a thicker oxide layer at Nb surface as an outcome of HPR. In this article, we report the production of oxide layer (FWHM thickness) based on different conditions such as the pressures and doses.
MOPB070	Quality Control of Cleanroom Processing Procedures of SRF Cavities for Mass Production	339
	R. Oweiss, K. Elliott, A. Facco, M. Hodek, I.M. Malloch, J. Popielarski, L. Popielarski, K. Saito FRIB, East Lansing, Michigan, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. Quality control is a key factor in the success of SRF cavity mass production. This paper summarizes ongoing research at the Facility for Rare Isotope Beams FRIB to validate the quality assurance of SRF cavities meanwhile optimizing processing procedures for mass production. Experiments are conducted to correlate surface cleanliness for niobium surfaces with high pressure rinse time using β=0.085 quarter-wave resonators (QWR) cavities. Diagnostic devices; liquid particle counter, surface particle detector and TOC analyzer are used to monitor key parameters for quality control. Rinse water samples are collected during high pressure rinsing to measure liquid particle counts. The SLS 1200 Sampler is used to detect the presence of liquid particles of 0.2 microns and up to 1 micron to set standards for acceptable cleaning thresholds and optimize high pressure rinse time. The QIII+ surface particle detector is used to scan high electric field region for the β=0.085 QWR to ensure high pressure rinsing efficiency. The β=0.085 QWR RF testing data are analyzed and results are presented to demonstrate the correlation between attained acceleration gradients and surface cleanliness.
MOPB071	Process Developments for Superconducting RF Low Beta Resonators for the ReA3 LINAC and Facility for Rare Isotope Beams	342
	L. Popielarski, C. Compton, L.J. Dubbs, K. Elliott, A. Facco, L.L. Harle, I.M. Malloch, R. Oweiss, J.P. Ozelis, J. Popielarski, K. Saito 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) will utilize over 330 superconducting radio frequency (SRF) low beta cavities for its heavy ion driver linac. The SRF department will process and test all cavities prior to string assembly in the cleanroom. The baseline cavity surface and bulk niobium processing procedures have been established. The methods are being optimized for production process rate benchmarking. Additional processes are being developed to increase flexibility and reduce technical risks. This paper will describe procedure developments and experimental results. Topics include high temperature heat treatment for hydrogen degassing, selective chemical etching for cavity frequency tuning, low-temperature bake out and process quality control.
MOPB072	Multipole Expansion of the Fields in Superconducting High-Velocity Spoke Cavities	345
	R.G. Olave, J.R. Delayen, C.S. Hopper ODU, Norfolk, Virginia, USA
	Multi-spokes superconducting cavities in the high-beta regime are being considered for a number of applications. In order to accurately model the dynamics of the particles in such cavities, knowledge of the fields off-axis are needed. We present a study of the multipoles expansion of the fields from an EM simulation field data for a two-spoke cavity operating at 325 MHz, β = 0.82 and 500 MHz, β = 1.
MOPB073	Cold Testing of Superconducting 72 MHz Quarter-wave Cavities for ATLAS	348
	M.P. Kelly, Z.A. Conway, S.M. Gerbick, M. Kedzie, R.C. Murphy, P.N. Ostroumov, T. Reid ANL, Argonne, USA
	A set of seven 72 MHz β=0.077 superconducting quarter-wave cavities for a beam intensity upgrade of the ATLAS heavy-ion accelerator has been completed. Cavities have been fabricated using the lessons learned from the worldwide effort to extend the performance of niobium cavities close to the limits of the material. Key developments include the use of electropolishing on the completed cavity and with a temperature control system substantially upgraded from that for elliptical-cell EP systems. Wire EDM, used instead of traditional niobium machining, appears to be effective in eliminating performance limiting defects near the weld seams. Hydrogen degassing at 600C after electropolishing permits practical acceleration at 2 Kelvin with Bpeak>120 mT and cavity voltages>5 MV/cavity.
MOPB074	Thermo-Mechanical Simulations of the Frequency Tuning Plunger for the IFMIF Half-Wave Resonator	351
	N. Bazin, P. Bosland, S. Chel, G. Devanz, N. Grouas, P. Hardy, J. Migne, F. Orsini, F. Peauger CEA/DSM/IRFU, France
	In the framework of the International Fusion Materials Irradiation Facility (IFMIF), a superconducting option has been chosen for the 5 MeV RF Linac of the first phase of the project (EVEDA), based on a cryomodule composed of 8 HWRs, 8 RF couplers and 8 Solenoid packages. The frequency tuning system of the IFMIF HWR is an innovated system based on a capacitive plunger installed in the electric field region allowing a large tuning range. Following the cold test results obtained on HWR equipped with the first design of plunger in 2011*, it was decided to develop a new design of a fully-niobium plunger. The paper will present the development of the new plunger concepts and the thermo-mechanical simulations. For the mechanical simulations, the aim is to sufficiently deform the plunger to tune the cavity while staying in the elastic range of the niobium material. For the thermal simulations, all the non-linear properties of the materials and the effects of the RF fields are taken into account: thermal conductivity and surface resistance are depending on the temperature, RF fields computed with dedicated software are leading to thermal dissipations in the materials and the vacuum seal. * F. Orsini et al., “Vertical tests preliminary results of the IFMIF cavity prototypes and cryomodule development”, SRF 2011, Chigaco, USA
MOPB077	Lorentz Force Detuning Compensation Studies for Long Pulses in ILC type SRF Cavities	354
	N. Solyak, G.I. Cancelo, B. Chase, D.J. Crawford, D.R. Edstrom, Jr, E.R. Harms, Y.M. Pischalnikov, W. Schappert Fermilab, Batavia, USA
	Project-X 3-8 GeV pulsed linac is based on ILC type 1.3 GHz elliptical cavities. The cavity will operate at 25 MV/m accelerating gradient, but in contrast with XFEL and ILC projects the required loaded Q is much higher (Q=107) and RF pulse is much longer (~8ms). For these parameters Lorence force detuning (LFD) and microphonics should be controlled at the level <30 Hz. A new algorithm of LFD compensation, developed at Fermilab for ILC cavities was applied for Lorentz force compensation studies for 8ms pulses. In these studies two cavities inside TESLA-type cryomodule at Fermilab NML facility have been powered by one klystron. Studies done for different cavity gradients and different values of loaded Q demonstrated that required compensation are achievable. Detuning measurements and compensation results are presented.
TH1A01	Results Achieved by the S1-Global Collaboration for ILC	748
	H. Hayano, M. Akemoto, S. Fukuda, K. Hara, N. Higashi, E. Kako, H. Katagiri, Y. Kojima, Y. Kondo, T. Matsumoto, S. Michizono, T. Miura, H. Nakai, H. Nakajima, K. Nakanishi, S. Noguchi, N. Ohuchi, T. Saeki, T. Shidara, T. Shishido, T. Takenaka, A. Terashima, N. Toge, K. Tsuchiya, K. Watanabe, S. Yamaguchi, A. Yamamoto, Y. Yamamoto, K. Yokoya KEK, Ibaraki, Japan C. Adolphsen, C.D. Nantista SLAC, Menlo Park, California, USA T.T. Arkan, S. Barbanotti, M.A. Battistoni, H. Carter, M.S. Champion, A. Hocker, R.D. Kephart, J.S. Kerby, D.V. Mitchell, T.J. Peterson, Y.M. Pischalnikov, M.C. Ross, W. Schappert, B.E. Smith Fermilab, Batavia, USA A. Bosotti, R. Paparella, P. Pierini INFN/LASA, Segrate (MI), Italy K. Jensch, D. Kostin, L. Lilje, A. Matheisen, W.-D. Möller, P. Schilling, M. Schmökel, N.J. Walker, H. Weise DESY, Hamburg, Germany C. Pagani Università degli Studi di Milano & INFN, Segrate, Italy
	The S1-Global collaboration (scope and plans presented at Linac10) ended successfully in 2011. In the S1-Global experiment several variants of ILC components (e.g. cavities, tuners, modules, couplers) proposed by all SCRF collaborators worldwide have been extensively tested and their performances compared, in order to build consensus for the technical choices towards the ILC TDR and to develop further the concept of plug-compatible components for ILC. The experiment has been carried at KEK with contribution of hardware and manpower from all collaborators.
	Slides TH1A01 [6.656 MB]
TH1A02	Compact Superconducting Crabbing and Deflecting Cavities	753
	S.U. De Silva ODU, Norfolk, Virginia, USA S.U. De Silva JLAB, Newport News, Virginia, USA
	Recently, new geometries for superconducting crabbing and deflecting cavities have been developed that have significantly improved properties over those the standard TM110 cavities. They are smaller, have low surface fields, high shunt impedance and, more importantly for some of them, no lower-order-mode with a well-separated fundamental mode. This talk will present the status of the development of these cavities.
	Slides TH1A02 [3.811 MB]
TH1A03	Superconducting Spoke Cavities for Electron and High-Velocity Proton Linacs	758
	J.R. Delayen ODU, Norfolk, Virginia, USA
	Spoke resonantors are currently under development for many proton machines but these structures are also considered for high beta electron linacs as well. These structures compare well to traditional elliptical cavities.
	Slides TH1A03 [3.570 MB]