LINAC2014 - List of Keywords (SRF)

Paper	Title	Other Keywords	Page
MOIOB01	Early Commissioning Experience and Future Plans for the 12 GeV Continuous Electron Beam Accelerator Facility	cryomodule, linac, operation, cavity	11
	M. Spata JLab, Newport News, Virginia, USA
	Jefferson Lab has recently completed the accelerator portion of the 12 GeV Upgrade for the Continuous Electron Beam Accelerator Facility. All 52 SRF cryomodules have been commissioned and operated with beam. The initial beam transport goals of demonstrating 2.2 GeV per pass, greater than 6 GeV in 3 passes to an existing experimental facility and greater than 10 GeV in 5-1/2 passes have all been accomplished. These results along with future plans to commission the remaining beamlines and to increase the performance of the accelerator to achieve reliable, robust and efficient operations at 12 GeV are presented.
	Slides MOIOB01 [2.754 MB]

MOPP002	Design of a Superconducting Quarter-Wave Resonator for eRHIC	cavity, electron, linac, niobium	49
	S.V. Kutsaev, Z.A. Conway, M.P. Kelly, B. Mustapha, P.N. Ostroumov ANL, Argonne, USA S.A. Belomestnykh, I. Ben-Zvi Stony Brook University, Stony Brook, USA S.A. Belomestnykh, I. Ben-Zvi, Q. Wu, W. Xu BNL, Upton, Long Island, New York, USA B. P. Xiao SBU, Stony Brook, New York, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 and by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 The electron-ion collider project (eRHIC) at Brookhaven National Laboratory requires a 50 mA 12 MeV electron injector linac for eRHIC main linac and an SRF electron gun for a Coherent electron Cooling (CeC) linac. The necessity to deal with long electron bunches required for both the eRHIC injector and the coherent electron cooler sets the frequency requirement of 84.5 MHz. Quarter wave resonator is a perfect choice for this frequency because of its dimensions, RF parameters and good experience with manufacturing and using them at ANL. Here we present the design and optimization of an 84.5 MHz 2.5 MV superconducting quarter-wave cavity suitable for both machines. One such QWR will be used as a bunching cavity in the injector linac, the other one as the photoemission electron source for the CeC linac. In addition to the optimization of the QWR electromagnetic design we will discuss the tuner design, approaches to cavity fabrication and processing.

MOPP012	Beam Commissioning of the SRF 704 MHz Photoemission Gun	cathode, gun, cavity, electron	70
	W. Xu, S.A. Belomestnykh, I. Ben-Zvi, D.M. Gassner, H. Hahn, J.P. Jamilkowski, P. Kankiya, D. Kayran, N. Laloudakis, R.F. Lambiase, G.T. McIntyre, D. Phillips, V. Ptitsyn, K.S. Smith, R. Than, D. Weiss, A. Zaltsman BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, I. Ben-Zvi, V. Ptitsyn Stony Brook University, Stony Brook, USA D. Holmes AES, Medford, New York, USA
	Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE. A 704 MHz superconducting RF photoemission electron gun for the R&D ERL project is under comissioning at BNL. Without a cathode insert, the SRF gun achieved its design goal: an accelerating voltage of 2 MV in CW mode. During commissioning with a copper cathode insert it reached 1.9 MV with 18% duty factor, which is limited by mulitpacting in a choke-joint cathode stalk. A new cathode stalk has been designed to eliminate multipacting in the choke-joint. This paper presents recent commissioning results, including cavity commissioning without the cathode stalk insert, first beam commissioning of the SRF gun in pulsed regime, and the design of a multipacting-free cathode stalk.

MOPP013	Vertical Test Results of 704 MHz BNL3 SRF Cavities	cavity, HOM, electron, damping	73
	W. Xu, S.A. Belomestnykh, I. Ben-Zvi, H. Hahn, R. Porgueddu, R. Than, D. Weiss BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, I. Ben-Zvi Stony Brook University, Stony Brook, USA C.H. Boulware, T.L. Grimm Niowave, Inc., Lansing, Michigan, USA M.D. Cole, D. Holmes, T. Schultheiss AES, Medford, New York, USA
	Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE, and Award No. DE-SC0002496 to Stony Brook University with the U.S. DOE. An electron-ion collider (eRHIC) proposed at BNL requires superconducting RF cavities able to support high average beam current. A 5-cell niobium SRF cavity, called BNL3, was designed for a conventional lattice eRHIC design. To avoid inducing emittance degradation and beam-break-up (BBU), the BNL3 cavity was optimized to damp all dangerous higher-order-modes (HOMs) by employing a large beam pipes and coaxial antenna-type couplers. Additionally, the cavity was designed for an acceptable cryogenic load and peak surface RF fields. Two BNL3 cavities have been fabricated and tested at a vertical test facility at BNL. This paper addresses development of the SRF cavities for eRHIC, including SRF cavity design, fabrication and test results.

MOPP016	Extracting Superconducting Parameters from Surface Resistivity by Using Inside Temperature of SRF Cavities	cavity, accelerating-gradient, electron, superconductivity	80
	G.M. Ge, G.H. Hoffstaetter, M. Liepe, H. Padamsee, V.D. Shemelin Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	The surface resistance of an RF superconductor depends on the surface temperature, the residual resistance and various superconductor parameters. These parameters can be determined by measuring the quality factor of a SRF cavity in helium-baths of different temperatures. The surface resistance can be computed from Q0 for any cavity geometry, however it is less simple to determine the temperature of the surface when only the temperature of the helium bath is known. Traditionally, it was approximated that the surface temperature on the inner surface of the cavity is the same as the temperature of the bath. This is a good approximation at small RF-field losses on the surface, but to determine the field dependence of Rs, one cannot be restricted to small field losses. Here we show how computer simulations can be used to determine the inside temperature so that Rs(Tin) can then be used to extract superconductor parameters. The computer code combines the well-known programs HEAT and SRIMP. We find that the error of the incorrect fitting method is about 10% at high RF-fields.

MOPP017	Cool Down and Flux Trapping Studies on SRF Cavities	cavity, cryomodule, linac, operation	84
	D. Gonnella, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Recent results from Cornell and FNAL have shown that cool down rate can have a strong impact on the residual resistance of a superconducting RF cavity during operation. We have studied the effect of cool down rate, gradient, and external magnetic field during cool down on the residual resistance of an EP, EP+120C baked, and nitrogen-doped cavities. For each cavity, faster cool down and large gradient resulted in lower residual resistance in vertical test. The nitrogen-doped cavities showed the largest improvement with fast cool down, while the EP+120C cavity showed the smallest. The cavities were also placed in a uniform external magnetic field and residual resistance was measured as a function of applied field and cool down rate. We show that the nitrogen-doped cavity was the most susceptible to losses from trapped flux and the EP+120C cavity was least susceptible. These measurements provide new insights into understanding the physics behind the observed impact of cool down rates and gradients on the performance of cavities with differing preparations.

MOPP018	Nitrogen-Doped 9-Cell Cavity Performance in the Cornell Horizontal Test Cryomodule	cavity, cryomodule, radiation, linac	88
	D. Gonnella, R.G. Eichhorn, F. Furuta, G.M. Ge, D.L. Hall, Y. He, G.H. Hoffstaetter, M. Liepe, T.I. O'Connel, S. Posen, P. Quigley, J. Sears, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA A. Grassellino, A. Romanenko Fermilab, Batavia, Illinois, USA
	Funding: U.S. Department of Energy Cornell has recently completed construction and qualification of a horizontal cryomodule capable of holding a 9-cell ILC cavity. A nitrogen-doped niobium 9-cell cavity was assembled into the Horizontal Test Cryomodule (HTC) with a high Q input coupler and tested. We report on results from this test of a nitrogen-doped cavity in cryomodule and discuss the effects of cool down rate and thermal cycling on the residual resistance of the cavity.

MOPP019	Nb3Sn Materials Studies	niobium, cavity, electron, ion	92
	S. Posen, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA Th. Proslier ANL, Argonne, Illinois, USA
	Nb₃Sn is a very promising material for use in SRF cavity applications, potentially offering significant improvements in quality factor and energy gradient compared to niobium. In order to better understand how to optimize this material for SRF applications, Nb₃Sn samples were prepared at Cornell via vapor deposition, using varying parameters in the coating process. Microscopic studies were performed with SEM/EDX, and studies were performed on bulk samples to measure secondary electron yield, energy gap, and upper critical magnetic field. The results are presented here, with discussion for how they might point the way towards reaching even higher fields in Nb₃Sn cavities.
	Poster MOPP019 [2.742 MB]

MOPP054	Continuous-Wave Horizontal Tests of Dressed 1.3 GHz SRF Cavities for LCLS-II	cavity, HOM, controls, linac	177
	A. Hocker, A.C. Crawford, M. Geynisman, J.P. Holzbauer, A. Lunin, D.A. Sergatskov, N. Solyak, A.I. Sukhanov Fermilab, Batavia, Illinois, USA
	Funding: United States Department of Energy, Contract No. DE-AC02-07CH11359 Fermilab’s Horizontal Test Stand has recently been upgraded to provide CW RF testing capabilities in support of the LCLS-II project at SLAC. Several cavities have been tested in this new configuration in order to validate component designs and processes for meeting the requirements of LCLS-II. Areas of study included gradient and Q0 performance and their dependence on extrinsic factors, thermal performance of the input coupler and HOM feedthroughs, and microphonics and RF control. A description of the testing and the results obtained are presented.
	Poster MOPP054 [0.276 MB]

MOPP071	BESSY VSR 1.5 GHz Cavity Design and Considerations on Waveguide Damping	damping, cavity, HOM, operation	221
	A.V. Velez, J. Knobloch, A. Neumann HZB, Berlin, Germany
	The BESSY VSR upgrade of the BESSY II light source represents a novel approach to simultaneously store long (ca. 15ps) and short (ca. 1.5ps) bunches in the storage ring with the present user optics. To this end, new high-voltage L-Band superconducting multi-cell cavities must be installed in one of the straights of the ring. These 1.5 GHz and 1.75 GHz cavities are based on 1.3 GHz systems being developed for the BERLinPro energy-recovery linac. This paper describes the baseline electromagnetic design of the first 5-cell cavity operating at 1.5 GHz.
	Poster MOPP071 [1.088 MB]

MOPP081	The ECT System for RAON's Cavities	cavity, experiment, niobium, controls	242
	M.J. Joung, Y. Jung, H.J. Kim IBS, Daejeon, Republic of Korea
	The ECT system is in use for Nb surface control in many laboratories. This system can inspect Nb surface quickly using high resolution. The ECT system for RAON's cavity was made with the feature : It has 3-axis acting probe movement system, It can inspect big size of Nb sheet, which is 1m by 1m and It contain the analysis program that can show the result as 2D and 3D image as well as relative figure of surface level. The standard sample was made with various sizes of defects using the same Nb sheet that was used to make RISP cavity. The ECT system conditioining was carried out to optimize ECT operation on the frequency, the range is from 300kHz to 2MHz. The result of 900 kHz shows the strongest signal. The conditioning experiment on other parameter will be carried out in near future. .

MOPP115	Plasma Processing of Nb Surfaces for SRF Cavities	plasma, cavity, accelerating-gradient, vacuum	323
	P.V. Tyagi, M. Doleans, S.-H. Kim ORNL, Oak Ridge, Tennessee, USA R. Afanador, C.J. McMahan ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: This work is supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. Field emission is one of the most critical issues to achieve high performances of niobium (Nb) superconducting radio frequency (SRF) cavities. Field emission is mainly related to contaminants present at top surface of SRF cavities that act as electron emitters at high gradient operation and limit the cavity accelerating gradient. An R&D program at the Spallation Neutron Source (SNS) is in place* aiming to develop an in-situ plasma processing technique to remove some of the residual contaminants from inner surfaces of Nb cavities and improve their performance. The plasma processing R&D has first concentrated on removing hydrocarbon contamination from top surface of SRF cavities. Results from the surface studies on plasma processed Nb samples will be presented in this article and showed the removal of hydrocarbons from Nb surfaces as well as improvement of the surface workfuntion (WF). *M. Doleans et al. “Plasma processing R&D for the SNS superconducting linac RF cavities” Proceedings of 2013 SRF workshop, Paris, France
	Slides MOPP115 [1.405 MB]

TUIOA02	R&D Efforts for ERLs	linac, emittance, cavity, operation	394
	R.G. Eichhorn Cornell University, Ithaca, New York, USA
	The last few years has seen extensive R&D for ERLs, with several prototype facilities now under construction or in operation. The Cornell ERL R&D program has reached major goals, with producing the world’s brightest beam from any photoinjector, reaching CW beam current of greaters than 75 mA, and reaching intrinsic quality factors of 10¹¹ in an SRF cavity installed in a cryomodule. The talk gives an overview of status of ERLs projects, and ERL R&D.
	Slides TUIOA02 [8.803 MB]

TUIOC03	Nb3Sn - Present Status and Potential as an Alternative SRF Material	cavity, niobium, linac, cryogenics	431
	S. Posen, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Nb₃Sn is a material that has the potential to have a transformative impact on SRF linacs. Due to its large critical temperature of approximately 18 K, Nb₃Sn cavities can have far smaller surface resistances at a given temperature than standard Nb cavities. This could significantly reduce the costs for infrastructure and power in cryoplants for large CW linacs. In addition, the predicted superheating field of Nb₃Sn is approximately double that of Nb, potentially doubling the maximum energy gradient. This would significantly decrease the size and cost of high energy linacs. In this work, we present recent progress in research and development for this promising material.
	Slides TUIOC03 [3.357 MB]
	Poster TUIOC03 [2.046 MB]

TUPP002	Commissioning of the 72 MHz Quarter-Wave Cavity Cryomodule at ATLAS	cavity, cryomodule, ion, operation	440
	M.P. Kelly, Z.A. Conway, S.M. Gerbick, M. Hendricks, M. Kedzie, S.H. Kim, S.W.T. MacDonald, R.C. Murphy, P.N. Ostroumov, T. Reid, S.I. Sharamentov, G.P. Zinkann ANL, Argonne, Illinois, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under contract number DE-AC02-06CH11357. A cryomodule of seven 72 MHz SC quarter-wave cavities optimized for ions with v/c=0.077 has been commissioned in the ATLAS heavy-ion accelerator at Argonne. ATLAS has a new capability for increased beam currents with low beam losses for nuclear physics experiments using stable or rare isotope beams or neutron rich beams from the Californium Rare Isotope Breeder. The main goal for the cryomodule, to provide an accelerating voltage of 17.5 MV (2.5 MV/cavity), with no detectable beam losses has been met within the first month of commissioning. Thus far, cavities and primary subsystems including high-power couplers and pneumatic tuners are operating as designed with full availability. For present levels there is practically no field emission (EPEAK=40 MV/m) and RF losses of ~5 Watts/cavity are only half of that planned. Cavity fields will continue to be gradually increased, with the limits due to cavity quench measured at VACC=3.75 MV. Due to a combination of rf design and cavity processing, effective voltages are now 2 ½ times those for any other operational cavities for this v/c. We report here on the recent online test results and technical features of the present design.

TUPP018	Analysis of Systematic and Random Error in SRF Material Parameter Calculations	simulation, cavity, extraction, niobium	465
	S.J. Meyers, M. Liepe, S. Posen Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA M. Liepe Cornell University, Ithaca, New York, USA
	Funding: NSF Career award PHY-0841213 and DOE award ER41628 To understand the relationship between an RF cavity’s performance and the material on its surface, one must look at various parameters, including energy gap, mean free path, and residual resistance. Though SRIMP fits for seven parameters, three parameters are eliminated using measurement and literature values, and the uncertainty of the fit of the remaining four parameters is further reduced by synthesizing two 3-parameter fits, each from a different data set. To study random error, Monte Carlo simulations were performed of ideal data with added noise; for systematic error, contour plots of normalized residual sum of squares (RSS) of the polymorphic fit on inputted data were generated.
	Poster TUPP018 [1.183 MB]

TUPP040	Preliminary Functional Analysis of ESS Superconducting Radio-Frequency Linac	cryomodule, vacuum, controls, interface	522
	C. Darve, N. Elias, J. Fydrych, D.P. Piso ESS, Lund, Sweden
	The European Spallation Source (ESS) is one of Europe's largest planned research infrastructures. The collaborative project is funded by a collaboration of 17 European countries and is under design and construction in Lund, Sweden. Three families of Superconducting Radio-Frequency (SRF) cavities are being prototyped, counting the spoke resonators with a geometric beta of 0.5, medium-beta elliptical cavities (βg=0.67) and high-beta elliptical cavities (bg=0.86). The 5 MW, 2.86 ms long pulse proton accelerator has a repetition frequency of 14 Hz (4 % duty cycle), and a beam current of 62.5 mA. The cavities and power couplers are assembled into cryomodules, which are operating using RF sources, cryogenic and water coolings. This document describes the process of the ESS SRF cryomodule operation while refereeing to operational modes.

TUPP052	SSR1 Tuner Mechanism: Passive and Active Device	cavity, cryomodule, alignment, operation	541
	D. Passarelli Fermilab, Batavia, Illinois, USA
	In this paper we present the methodology adopted in designing the mechanism responsible for controlling the resonant frequency of Single Spoke Resonators of first type (SSR1). Such device is capable of compensating the effects of external perturbations, such as pressure fluctuations and microphonics, on the frequency of SSR1. The compensation is achieved through active responses via an actuation system and passive responses which are inherent to the elastic behavior of the overall system. The first experiences in the design, assembly, QA and testing are reported.
	Poster TUPP052 [2.368 MB]

TUPP055	Progress on Euclid SRF Conical Half-Wave Resonator Project	cavity, niobium, vacuum, proton	547
	E.N. Zaplatin FZJ, Jülich, Germany T.L. Grimm Niowave, Inc., Lansing, Michigan, USA A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio, USA V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Funding: This Work is supported by the DOE SBIR Program, contract # DE-SC0006302. Euclid conical Half-Wave Resonator (cHWR) project develops 162.5 MHz β=v/c=0.11 accelerator structure for the high-intensity proton accelerator complex proposed at Fermi National Accelerator Laboratory. The main idea of this project is to provide a self-compensation cavity design together with its helium vessel to minimize the resonant frequency dependence on external loads. A unique cavity side-tuning option is also under development. Niowave, Inc. proposed a complete cavity production procedure including preparation of technical drawings, processing steps and resonator high-gradient tests to demonstrate such possibility for the private company. Here we present the procedure of the cavity and helium vessel fabrication, cavity preparation and initial experimental results.

TUPP065	RF Input Power Couplers for High Current SRF Applications	cavity, booster, linac, simulation	575
	V.F. Khan, W. Anders, A. Burrill, J. Knobloch, O. Kugeler, A. Neumann HZB, Berlin, Germany H. Wang JLab, Newport News, Virginia, USA
	High current SRF technology is being explored in present day accelerator science. The BERLinPro project is presently being built at the HZB to address the challenges involved in high current SRF machines. A 100 mA electron beam is designed to be accelerated to 50 MeV in continuous wave (cw) mode at 1.3 GHz. One of the main challenges in this project is that of handling high input RF power for the gun as well as booster cavities where there is no energy recovery process. A high power co-axial input coupler is being developed to be used for the booster and gun cavities at the nominal beam current. The coupler is based on the KEK–cERL coupler design. The KEK coupler design has been modified to minimise the penetration of the tip in the beampipe without compromising on beam-power coupling ( Qext ~1 x 105). Herein we report on the RF design for the high power (130 kW) BERLinPro (BP) couplers along with the test stand for conditioning the couplers. We will also report on the RF conditioning of the TTF-III couplers modified for cw operation (low power ~ 10 kW) which will be utilised in a new 4-mA SRF Photoinjector and the BERLinPro main linac cryomodule.
	Slides TUPP065 [2.465 MB]

TUPP066	Commissioning Results of the 2nd 3.5 Cell SRF Gun for ELBE	gun, cavity, electron, solenoid	578
	A. Arnold, M. Freitag, P. Murcek, J. Teichert, H. Vennekate, R. Xiang HZDR, Dresden, Germany G. Ciovati, P. Kneisel, L. Turlington JLab, Newport News, Virginia, USA
	As in 2007 the first 3.5 cell superconducting radio frequency (SRF) gun was taken into operation at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), it turned out that the specified performance to realize an electron energy gain of 9.4 MeV (Epk=50 MV/m @ Q0=10¹⁰) has not been achieved. Instead, the resonator of the gun was limited by field emission to about one third of these values and the measured beam parameters remained significantly behind the expectations. However, to demonstrate the full potential of this new electron source for the ELBE LINAC, a second and slightly modified SRF gun was developed and built in collaboration with Thomas Jefferson National Accelerator Facility (TJNAF). We will report on commissioning and first results of this new SRF gun. This includes in particular the characterization of the most important RF properties of the cavity as well as their comparison with previous vertical test results.
	Poster TUPP066 [1.220 MB]

TUPP068	New SRF Facility at KEK for Mass-Production Study in Collaboration with Industries	cryomodule, cavity, operation, cryogenics	584
	H. Hayano KEK, Ibaraki, Japan
	The construction of the new SRF facility next to the KEK-STF facility has started from 2014 for the mass-production study of SRF accelerators in collaboration with industries. The new building for this facility has the dimension of 80 m x 30 m, and the plan is to install clean-room for cavity-string assembly, cryomodule-assembly facility, cryogenic system, vertical test facility, cryomodule test facility, input coupler process facility, cavity Electro-Polishing (EP) facility, and control-room/office-rooms in it. The purpose of this new SRF facility is to establish a close collaboration between SRF researchers and industries in order to prepare for the upcoming large-scale future SRF project, like ILC. This paper describes the infra-structure detail and the plan to utilize for future SRF accelerators.

TUPP083	Design and Analysis of Slow Tuner in the Superconducting Cavity of RISP	cavity, superconducting-cavity, niobium, target	616
	M.O. Hyun, H.C. Jung, H.J. Kim IBS, Daejeon, Republic of Korea
	Funding: This work was supported by the Rare Isotope Science Project of Institute of Basic Science funded by the Ministry of Science, ICT and Future Planning and National Research Foundation. Superconducting cavity is one of the most complex systems from the view of mechanical engineering, which is installed and operated in the superconducting linear accelerator. In order to operate SC cavity properly and precisely, superconducting cavity needs many sub-systems, including power coupler for applying RF power inside cavity, and liquid helium jacket for cooling cavity until reaching to the superconducting conditions. And, also cavity needs frequency tuning system for adjusting operating frequency when RF frequency of cavity is changed with outer disturbances such as liquid helium fluctuation, mechanical deformation due to vacuum condition of cavity. Generally, this tuning system is called as a tuner. There are two types of tuner, one is slow tuner which operates with motor, and the other is fast tuner which operates with piezo-electric actuator. This paper describes about design process and analysis results about slow tuner.

TUPP086	RAON Superconducting Radio Frequency Test Facility Construction	cavity, radiation, cryogenics, electron	625
	H. Kim, D. Jeon, Y.W. Jo, Y. Jung, S.A. Kim, W.K. Kim, S.J. Lee, S.W. Nam, G.-T. Park, J.H. Shin IBS, Daejeon, Republic of Korea
	Superconducting Radio Frequency (SRF) test facility for RAON is under construction process. It consists of cryogenic system, clean room for cavity process and assembles vertical test, horizontal test, and the radiation shield. The cryoplant has 330 W (4.5 K equivalent) which supplies 4.5K supercritical helium to the cavity test and cryomodule test bench. Clean rooms are for cavity process and assemble whose class is from 10 to 10000. The layout for the vertical and horizontal test bench is shown and the radiation shield for the test bench is shown to reduce X-ray coming from cavity. To estimate the thickness of concrete, radiation simulation is performed.

TUPP138	Analysis of New High-Q0 SRF Cavity Tests by Nitrogen Gas Doping at Jefferson Lab	cavity, injection, niobium, vacuum	736
	A.D. Palczewski, R.L. Geng, C.E. Reece JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. In order to refine systematic understanding and establish confident process control, Jefferson Lab has joined with partners to investigate and thoroughly characterize the dramatically higher Q0 of 1.3 GHz niobium cavities first reported by FNAL in 2013[1]. With partial support from the LCLS-II project, JLab has undertaken a parametric study of nitrogen doping in vacuum furnace at 800 C followed by variable depth surface removal in the 5 - 20 μm range. Q0 above 3×10¹⁰ are typical at 2.0 K and 16 MV/m accelerating field. We report observations from the single cell study and current interpretations. In addition to the parametric single cell study, we also report on the ongoing serial testing of six nitrogen-doped 9-cell cavities as baseline prototypes for LCLS-II. [1] A. Grassellino, et al., Supercon. Sci.and Tech., 2013. 26(10): p. 102001
	Poster TUPP138 [4.214 MB]

WEIOA06	Low Level RF for SRF Accelerators	LLRF, cavity, controls, operation	760
	J. Branlard DESY, Hamburg, Germany
	Low level radio frequency (LLRF) systems are a fundamental component of superconducting RF accelerators. Since the release of the MicroTCA standard (MTCA.4), major developments in MTCA.4-based LLRF systems have taken place. State-of-the-art LLRF designs deliver better than 10^-4 relative amplitude and 10 mdeg phase stability for the vector sum control of SRF cavities. These developments in LLRF systems architecture and technology, driven by research institutes and supported by the industry are of highest importance for the European XFEL, but also for other SRF-based projects such as LCLS-II and the ESS, as well as for the next generation accelerators with 10-5 and mdeg regulation requirements.
	Slides WEIOA06 [5.812 MB]

THIOA02	Superconducting RF Development for FRIB at MSU	cavity, cryomodule, solenoid, operation	790
	K. Saito, N.K. Bultman, E.E. Burkhardt, F. Casagrande, S.K. Chandrasekaran, S. Chouhan, C. Compton, J.L. Crisp, K. Elliott, A. Facco, A.D. Fox, P.E. Gibson, M.J. Johnson, G. Kiupel, R.E. Laxdal, M. Leitner, S.M. Lidia, 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, T. Russo, S. Shanab, M. Shuptar, S. Stark, N.R. Usher, G.J. Velianoff, D.R. Victory, J. Wei, G. Wu, X. Wu, T. Xu, T. Xu, Y. Yamazaki, Q. Zhao, Z. Zheng 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. FRIB is a $730M heavy ion accelerator project and a very large scale machine for many nuclear physics users. The civil construction started on March 17th 2014. The SRF system design and development have completed. The machine is to be in early completion end of 2019. FRIB accelerates ion species up to 238U with energies of no less than 200MeV/u and provides a beam power up to 400kW. Four SRF cavity families are used from β=0.041, 0.085 (QWRs) to 0.29 and 0.53 (HWRs). 8T superconducting solenoids are installed in the cryomodules for space effective strong beam focusing. The biggest challenges are in accelerating the high-power heavy ion beams from the very low energy to medium energy and the stable operation for large user community. The SRF cryomodule design addressed three critical issues: high performance, stable operation and easy maintainability, which chose several unique technical strategies, e.g.2K operation, bottom up cryomodule assembly, local magnetic shielding and so on. This talk will include high performance cavity R&D, local magnetic shielding, flux trapping by solenoid fringe field, and bottom up cryomodule assembly.
	Slides THIOA02 [5.049 MB]

THIOB01	Cryogenic Plants for SRF Linacs	vacuum, cryomodule, linac, cryogenics	811
	D. Arenius JLab, Newport News, Virginia, USA
	Review of the types of considerations that go into cryo-plant design. Arenius is a world expert on this topic and has led the completion of the upgraded cryo-plant at Jefferson Lab, and has recently provided substantial input on this question to the new LCLS II project.
	Slides THIOB01 [4.382 MB]

THPP016	Nitrogen-Treated Cavity Testing at Cornell	cavity, niobium, linac, vacuum	866
	D. Gonnella, F. Furuta, G.M. Ge, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: U.S. Department of Energy Recent results from Cornell, FNAL, and TJNAF have shown that superconducting RF cavities given a heat treatment in a nitrogen atmosphere show higher Q₀ at operating gradients at 2.0 K than standard SRF cavities. Here we present on recent results at Cornell in which five single cell cavities and three 9-cell cavities were tested after receiving various nitrogen-doping treatments. Cavity performance was correlated with treatment, and samples treated with the cavities were analyzed with SIMS. These results provide new insights into the science behind the excellent performance that is observed in these cavities.

THPP018	Sample Plate Studies Using a High Field TE Cavity With Thermometry Mapping System	cavity, niobium, coupling, experiment	873
	D.L. Hall, C.D. Burton, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: NSF Career Grant PHY-0841213 A TE-Mode sample plate cavity capable of sustaining peak fields of >90 mT on the surface of a 10cm diameter sample plate has been developed and tested at Cornell. A thermometry mapping system composed of 40 Allen-Bradley resistors, mounted on the outside of the sample plate, is capable of measuring the surface resistance of the sample with a resolution of 1 nOhm and a spatial resolution of 0.5 cm. In this paper we present the design and expected performance of this high field TE cavity, and show data taken with a sample plate of niobium as well as results from tests qualifying the performance of the thermometry mapping system.

THPP021	Analysis of the RF Test Results from the On-going Accelerator Cavity Production for the European XFEL	cavity, superconductivity, linac, operation	879
	D. Reschke, S. Aderhold, V. Gubarev, J. Schaffran, N.J. Walker DESY, Hamburg, Germany L. Monaco INFN/LASA, Segrate (MI), Italy Y. Yamamoto KEK, Ibaraki, Japan
	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 superconducting accelerator modules, operated at an average design gradient of 23.6 MV/m. The fabrication by industry (which includes chemical surface preparation) of the required 800 superconducting cavities is now in full swing, with approximately 400 cavities having been delivered to date. In this interim report, we present an analysis of the RF acceptance tests amassed so far.

THPP031	Plans for an ERL Test Facility at CERN	cavity, cryomodule, electron, linac	905
	E. Jensen, O.S. Brüning, R. Calaga, K.M. Schirm, R. Torres-Sanchez, A. Valloni CERN, Geneva, Switzerland K. Aulenbacher IKP, Mainz, Germany S.A. Bogacz, A. Hutton JLab, Newport News, Virginia, USA M. Klein The University of Liverpool, Liverpool, United Kingdom
	The baseline electron accelerator for LHeC and one option for FCC-he is an Energy Recovery Linac. To prepare and study the necessary key technologies, CERN has started – in collaboration with JLAB and Mainz University – the conceptual design of an ERL Test Facility (ERL-TF). Staged construction will allow the study under different conditions with up to 3 passes, beam energies of up to about 1 GeV and currents of up to 50 mA. The design and development of superconducting cavity modules, including coupler and HOM damper designs, are also of central importance for other existing and future accelerators and their tests are at the heart of the current ERL-TF goals. The ERL-TF could also provide a unique infrastructure for several applications that go beyond developing and testing the ERL technology at CERN. In addition to experimental studies of beam dynamics, operational and reliability issues in an ERL, it could equally serve for quench tests of superconducting magnets, as physics experimental facility on its own right or as test stand for detector developments. This contribution will describe the goals and the concept of the facility and the status of the R&D.

THPP046	SRF Highbay Technical Infrastructure for FRIB Production at Michigan State University	cavity, cryomodule, vacuum, controls	954
	L. Popielarski, F. Casagrande, C. Compton, T. Elkin, A. Fila, P.E. Gibson, M. Hodek, L. Hodges, I.M. Malloch, C. Nguyen, R. Oweiss, J.P. Ozelis, J. Popielarski, C. Thronson, D.R. Victory, T. Xu FRIB, East Lansing, Michigan, USA M. Leitner LBNL, Berkeley, California, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE- SC0000661 Michigan State University (MSU) has funded the construction of a new 27,000 square foot high bay building to house the Superconducting Radio Frequency (SRF) infrastructure for the Facility for Rare Isotope Beams (FRIB) production requirements. The construction has been completed and beneficial occupancy began on May 19th, 2014. The new SRF highbay includes over 4,000 square feet of cleanroom and chemistry facility space, automated cavity etch tools, ultra pure water systems, cold mass component inspection area, hydrogen degassing furnace, SRF testing capabilities for three vertical test Dewars and two horizontal cryomodule test bunkers with dedicated helium refrigeration system. The status of the technical equipment design, installation and commissioning will be presented.

THPP048	Design of a Compact Lever Slow/Fast Tuner for 650 MHz Cavities for Project X	cavity, operation, resonance, simulation	957
	I.V. Gonin, E. Borissov, T.N. Khabiboulline, Y.M. Pischalnikov, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Fermilab is developing 5-cell elliptical 650 MHz β=0.6 and β=0.9 cavities for Project X. A compact fast/slow lever tuner intended for both types of cavities has been developed for final tuning of the resonance frequency of the cavity after cooling down and to compensate the resonance frequency variations of the cavity during operation coming from liquid helium pressure fluctuations. The updated helium vessel (presented at this conference) is equipped with the tuner located at one of the end of the cavity. The tuner design and results of ANSYS analysis of their properties are presented.

THPP057	Results of Cold Tests of the Fermilab SSR1 Cavities	cavity, cryomodule, radiation, resonance	979
	A.I. Sukhanov, M.H. Awida, P. Berrutti, E. Cullerton, B.M. Hanna, A. Hocker, T.N. Khabiboulline, O.S. Melnychuk, D. Passarelli, R.V. Pilipenko, Y.M. Pischalnikov, L. Ristori, A.M. Rowe, W. Schappert, D.A. Sergatskov Fermilab, Batavia, Illinois, USA
	Fermilab is currently building the Project X Injector experiment (PXIE). The PXIE linac will accelerate a 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. We discuss tests of nine bare SSR1 cavities at the Fermilab Vertical Test Stand (VTS). Recently, one of the SSR1 cavities was welded inside a helium jacket. Results of the test of this cavity in the Fermilab Spoke Test Cryostat (STC) are shown. We report on the measured performance parameters of SSR1 cavities achieved during the tests.

THPP062	BERLinPro SRF Gun Notch Filter Investigations	gun, cathode, cavity, resonance	995
	E.N. Zaplatin FZJ, Jülich, Germany J. Knobloch, A. Neumann HZB, Berlin, Germany
	BERLinPro is an approved ERL project to demonstrate energy recovery at 100 mA beam current by pertaining a high quality beam. These goals place stringent requirements on the SRF cavity (1300 MHz, β=1) for the photoinjector which has to deliver a small emittance 100 mA beam with at least 1.8 MeV kinetic energy while limited by fundamental power coupler performance to about 230 kW forward power. The RF and beam dynamics gun cavity features 1.4 λ/2 cell resonator. To protect a cathode housing from RF power propagation from the cavity cells and to reduce its component heating a high-frequency notch filter was investigated. We present results of different schemes of choke cell combinations to optimize filter parameters. The goal for the filter design was the RF power attenuation better than -30 dB in the wide frequency range.

THPP072	BERLinPro Booster Cavity Design, Fabrication and Test Plans	cavity, cryomodule, booster, linac	1019
	A. Burrill, W. Anders, A. Frahm, J. Knobloch, A. Neumann HZB, Berlin, Germany G. Ciovati, P. Kneisel, L. Turlington JLab, Newport News, Virginia, USA
	The BERLinPro project, a 100 mA, 50 MeV superconducting RF (SRF) Energy Recovery Linac (ERL) is under construction at Helmholtz-Zentrum Berlin for the purpose of studying the technical challenges and physics of operating a high current, c.w., 1.3 GHz ERL. This machine will utilize three unique SRF cryomodules for the injector, booster and linac module respectively. The booster cryomodule will contain three 2-cell SRF cavities, based on the original design by Cornell University, and will be equipped with twin 115 kW RF power couplers in order to provide the appropriate acceleration to the high current electron beam. This paper will review the status of the fabrication of the 4 booster cavities that have been built for this project by Jefferson Laboratory and look at the challenges presented by the incorporation of fundamental power couplers capable of delivering 115 kW. The test plan for the cavities and couplers will be given along with a brief overview of the cryomodule design.

THPP077	Fast Tuner Performance for a Double Spoke Cavity	cavity, operation, simulation, controls	1034
	N. Gandolfo, S. Bousson, S. Brault, P. Duchesne, P. Duthil, G. Olry, D. Reynet IPN, Orsay, France C. Darve, M. Lindroos ESS, Lund, Sweden
	IPN Orsay is developing the low-beta double Spoke cavities cryomodule for the ESS. In order to compensate resonant frequency variations of each cavity during operation, a deformation tuner has been studied and two of them have been built. The typical perturbations are coming from LHe saturated bath pressure variations as well as microphonics and Lorentz force detuning (LFD). In this paper, the tuner performance of the double Spoke cavity is presented.

THPP107	Study on Polishing Method of Nb Surface by Periodic Reverse Current Electrolysis With Alkali Solution	experiment, cavity, laser, operation	1102
	M. Umehara Nomura Plating Co, Ltd., Osaka, Japan H. Hayano, T. Saeki KEK, Ibaraki, Japan
	Currently, electropolising method is thought to be the best method for the final surface preparation of superconducting RF cavity to obtain high gradient. In this conventional electropolising method, the electrolyte is the mixture of fluoric and sulfuric acids. Therefore, the operation of this method is dangerous, and the equipment becomes expensive because all parts should be made of high density polyethylene or fluorocarbon resin to avoid metallic parts which suffers from corrosion by electrolyte. Moreover, sulfur is produced as byproduct in the electropolishing process and this causes degradation of cavity performance. In order to overcome these drawbacks, we studied new polishing method of Nb surface by periodic reverse current electrolysis with alkali solution which causes no sulfur and allows the usage of metallic parts to realize cost effective equipment. In the study, we performed experiment of Nb coupons by this new method and obtained as good surface roughness as conventional electropolishing method. In this article, we report the details of the study.

THPP135	Recent Improvements to Software Used for Optimization of SRF Linacs	cryomodule, cavity, linac, cryogenics	1174
	T. Powers JLab, Newport News, Virginia, USA
	Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. This work describes a 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 program includes estimates for the associated cryogenic facility, and controls hardware, where operation costs includes the cost of the electrical utilities but not the labor or other costs. The software interface provides the ability to vary the cost of the different aspects of the machine as well as to change the cryomodule and cavity types. Additionally, this work will describe the recent improvements to the software that allow one to estimate the costs of energy recovery based linacs and to enter arbitrary values of the low field Qo and Qo slope. The initial goal was to convert a spreadsheet 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. An example of how it was used to investigate the cost optimization tradeoffs for the LCLS 2 linac will also be presented.

Paper

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MOIOB01

Early Commissioning Experience and Future Plans for the 12 GeV Continuous Electron Beam Accelerator Facility

cryomodule, linac, operation, cavity

11

M. Spata
JLab, Newport News, Virginia, USA

Jefferson Lab has recently completed the accelerator portion of the 12 GeV Upgrade for the Continuous Electron Beam Accelerator Facility. All 52 SRF cryomodules have been commissioned and operated with beam. The initial beam transport goals of demonstrating 2.2 GeV per pass, greater than 6 GeV in 3 passes to an existing experimental facility and greater than 10 GeV in 5-1/2 passes have all been accomplished. These results along with future plans to commission the remaining beamlines and to increase the performance of the accelerator to achieve reliable, robust and efficient operations at 12 GeV are presented.

Slides MOIOB01 [2.754 MB]

MOPP002

Design of a Superconducting Quarter-Wave Resonator for eRHIC

cavity, electron, linac, niobium

49

S.V. Kutsaev, Z.A. Conway, M.P. Kelly, B. Mustapha, P.N. Ostroumov
ANL, Argonne, USA
S.A. Belomestnykh, I. Ben-Zvi
Stony Brook University, Stony Brook, USA
S.A. Belomestnykh, I. Ben-Zvi, Q. Wu, W. Xu
BNL, Upton, Long Island, New York, USA
B. P. Xiao
SBU, Stony Brook, New York, USA

Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 and by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357
The electron-ion collider project (eRHIC) at Brookhaven National Laboratory requires a 50 mA 12 MeV electron injector linac for eRHIC main linac and an SRF electron gun for a Coherent electron Cooling (CeC) linac. The necessity to deal with long electron bunches required for both the eRHIC injector and the coherent electron cooler sets the frequency requirement of 84.5 MHz. Quarter wave resonator is a perfect choice for this frequency because of its dimensions, RF parameters and good experience with manufacturing and using them at ANL. Here we present the design and optimization of an 84.5 MHz 2.5 MV superconducting quarter-wave cavity suitable for both machines. One such QWR will be used as a bunching cavity in the injector linac, the other one as the photoemission electron source for the CeC linac. In addition to the optimization of the QWR electromagnetic design we will discuss the tuner design, approaches to cavity fabrication and processing.

MOPP012

Beam Commissioning of the SRF 704 MHz Photoemission Gun

cathode, gun, cavity, electron

70

W. Xu, S.A. Belomestnykh, I. Ben-Zvi, D.M. Gassner, H. Hahn, J.P. Jamilkowski, P. Kankiya, D. Kayran, N. Laloudakis, R.F. Lambiase, G.T. McIntyre, D. Phillips, V. Ptitsyn, K.S. Smith, R. Than, D. Weiss, A. Zaltsman
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, I. Ben-Zvi, V. Ptitsyn
Stony Brook University, Stony Brook, USA
D. Holmes
AES, Medford, New York, USA

Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
A 704 MHz superconducting RF photoemission electron gun for the R&D ERL project is under comissioning at BNL. Without a cathode insert, the SRF gun achieved its design goal: an accelerating voltage of 2 MV in CW mode. During commissioning with a copper cathode insert it reached 1.9 MV with 18% duty factor, which is limited by mulitpacting in a choke-joint cathode stalk. A new cathode stalk has been designed to eliminate multipacting in the choke-joint. This paper presents recent commissioning results, including cavity commissioning without the cathode stalk insert, first beam commissioning of the SRF gun in pulsed regime, and the design of a multipacting-free cathode stalk.

MOPP013

Vertical Test Results of 704 MHz BNL3 SRF Cavities

cavity, HOM, electron, damping

73

W. Xu, S.A. Belomestnykh, I. Ben-Zvi, H. Hahn, R. Porgueddu, R. Than, D. Weiss
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, I. Ben-Zvi
Stony Brook University, Stony Brook, USA
C.H. Boulware, T.L. Grimm
Niowave, Inc., Lansing, Michigan, USA
M.D. Cole, D. Holmes, T. Schultheiss
AES, Medford, New York, USA

Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE, and Award No. DE-SC0002496 to Stony Brook University with the U.S. DOE.
An electron-ion collider (eRHIC) proposed at BNL requires superconducting RF cavities able to support high average beam current. A 5-cell niobium SRF cavity, called BNL3, was designed for a conventional lattice eRHIC design. To avoid inducing emittance degradation and beam-break-up (BBU), the BNL3 cavity was optimized to damp all dangerous higher-order-modes (HOMs) by employing a large beam pipes and coaxial antenna-type couplers. Additionally, the cavity was designed for an acceptable cryogenic load and peak surface RF fields. Two BNL3 cavities have been fabricated and tested at a vertical test facility at BNL. This paper addresses development of the SRF cavities for eRHIC, including SRF cavity design, fabrication and test results.

MOPP016

Extracting Superconducting Parameters from Surface Resistivity by Using Inside Temperature of SRF Cavities

cavity, accelerating-gradient, electron, superconductivity

80

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

The surface resistance of an RF superconductor depends on the surface temperature, the residual resistance and various superconductor parameters. These parameters can be determined by measuring the quality factor of a SRF cavity in helium-baths of different temperatures. The surface resistance can be computed from Q0 for any cavity geometry, however it is less simple to determine the temperature of the surface when only the temperature of the helium bath is known. Traditionally, it was approximated that the surface temperature on the inner surface of the cavity is the same as the temperature of the bath. This is a good approximation at small RF-field losses on the surface, but to determine the field dependence of Rs, one cannot be restricted to small field losses. Here we show how computer simulations can be used to determine the inside temperature so that Rs(Tin) can then be used to extract superconductor parameters. The computer code combines the well-known programs HEAT and SRIMP. We find that the error of the incorrect fitting method is about 10% at high RF-fields.

MOPP017

Cool Down and Flux Trapping Studies on SRF Cavities

cavity, cryomodule, linac, operation

84

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

Recent results from Cornell and FNAL have shown that cool down rate can have a strong impact on the residual resistance of a superconducting RF cavity during operation. We have studied the effect of cool down rate, gradient, and external magnetic field during cool down on the residual resistance of an EP, EP+120C baked, and nitrogen-doped cavities. For each cavity, faster cool down and large gradient resulted in lower residual resistance in vertical test. The nitrogen-doped cavities showed the largest improvement with fast cool down, while the EP+120C cavity showed the smallest. The cavities were also placed in a uniform external magnetic field and residual resistance was measured as a function of applied field and cool down rate. We show that the nitrogen-doped cavity was the most susceptible to losses from trapped flux and the EP+120C cavity was least susceptible. These measurements provide new insights into understanding the physics behind the observed impact of cool down rates and gradients on the performance of cavities with differing preparations.

MOPP018

Nitrogen-Doped 9-Cell Cavity Performance in the Cornell Horizontal Test Cryomodule

cavity, cryomodule, radiation, linac

88

D. Gonnella, R.G. Eichhorn, F. Furuta, G.M. Ge, D.L. Hall, Y. He, G.H. Hoffstaetter, M. Liepe, T.I. O'Connel, S. Posen, P. Quigley, J. Sears, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
A. Grassellino, A. Romanenko
Fermilab, Batavia, Illinois, USA

Funding: U.S. Department of Energy
Cornell has recently completed construction and qualification of a horizontal cryomodule capable of holding a 9-cell ILC cavity. A nitrogen-doped niobium 9-cell cavity was assembled into the Horizontal Test Cryomodule (HTC) with a high Q input coupler and tested. We report on results from this test of a nitrogen-doped cavity in cryomodule and discuss the effects of cool down rate and thermal cycling on the residual resistance of the cavity.

MOPP019

Nb3Sn Materials Studies

niobium, cavity, electron, ion

92

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

Nb₃Sn is a very promising material for use in SRF cavity applications, potentially offering significant improvements in quality factor and energy gradient compared to niobium. In order to better understand how to optimize this material for SRF applications, Nb₃Sn samples were prepared at Cornell via vapor deposition, using varying parameters in the coating process. Microscopic studies were performed with SEM/EDX, and studies were performed on bulk samples to measure secondary electron yield, energy gap, and upper critical magnetic field. The results are presented here, with discussion for how they might point the way towards reaching even higher fields in Nb₃Sn cavities.

Poster MOPP019 [2.742 MB]

MOPP054

Continuous-Wave Horizontal Tests of Dressed 1.3 GHz SRF Cavities for LCLS-II

cavity, HOM, controls, linac

177

A. Hocker, A.C. Crawford, M. Geynisman, J.P. Holzbauer, A. Lunin, D.A. Sergatskov, N. Solyak, A.I. Sukhanov
Fermilab, Batavia, Illinois, USA

Funding: United States Department of Energy, Contract No. DE-AC02-07CH11359
Fermilab’s Horizontal Test Stand has recently been upgraded to provide CW RF testing capabilities in support of the LCLS-II project at SLAC. Several cavities have been tested in this new configuration in order to validate component designs and processes for meeting the requirements of LCLS-II. Areas of study included gradient and Q0 performance and their dependence on extrinsic factors, thermal performance of the input coupler and HOM feedthroughs, and microphonics and RF control. A description of the testing and the results obtained are presented.

Poster MOPP054 [0.276 MB]

MOPP071

BESSY VSR 1.5 GHz Cavity Design and Considerations on Waveguide Damping

damping, cavity, HOM, operation

221

A.V. Velez, J. Knobloch, A. Neumann
HZB, Berlin, Germany

The BESSY VSR upgrade of the BESSY II light source represents a novel approach to simultaneously store long (ca. 15ps) and short (ca. 1.5ps) bunches in the storage ring with the present user optics. To this end, new high-voltage L-Band superconducting multi-cell cavities must be installed in one of the straights of the ring. These 1.5 GHz and 1.75 GHz cavities are based on 1.3 GHz systems being developed for the BERLinPro energy-recovery linac. This paper describes the baseline electromagnetic design of the first 5-cell cavity operating at 1.5 GHz.

Poster MOPP071 [1.088 MB]

MOPP081

The ECT System for RAON's Cavities

cavity, experiment, niobium, controls

242

M.J. Joung, Y. Jung, H.J. Kim
IBS, Daejeon, Republic of Korea

The ECT system is in use for Nb surface control in many laboratories. This system can inspect Nb surface quickly using high resolution. The ECT system for RAON's cavity was made with the feature : It has 3-axis acting probe movement system, It can inspect big size of Nb sheet, which is 1m by 1m and It contain the analysis program that can show the result as 2D and 3D image as well as relative figure of surface level. The standard sample was made with various sizes of defects using the same Nb sheet that was used to make RISP cavity. The ECT system conditioining was carried out to optimize ECT operation on the frequency, the range is from 300kHz to 2MHz. The result of 900 kHz shows the strongest signal. The conditioning experiment on other parameter will be carried out in near future. .

MOPP115

Plasma Processing of Nb Surfaces for SRF Cavities

plasma, cavity, accelerating-gradient, vacuum

323

P.V. Tyagi, M. Doleans, S.-H. Kim
ORNL, Oak Ridge, Tennessee, USA
R. Afanador, C.J. McMahan
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: This work is supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
Field emission is one of the most critical issues to achieve high performances of niobium (Nb) superconducting radio frequency (SRF) cavities. Field emission is mainly related to contaminants present at top surface of SRF cavities that act as electron emitters at high gradient operation and limit the cavity accelerating gradient. An R&D program at the Spallation Neutron Source (SNS) is in place* aiming to develop an in-situ plasma processing technique to remove some of the residual contaminants from inner surfaces of Nb cavities and improve their performance. The plasma processing R&D has first concentrated on removing hydrocarbon contamination from top surface of SRF cavities. Results from the surface studies on plasma processed Nb samples will be presented in this article and showed the removal of hydrocarbons from Nb surfaces as well as improvement of the surface workfuntion (WF).
*M. Doleans et al. “Plasma processing R&D for the SNS superconducting linac RF cavities” Proceedings of 2013 SRF workshop, Paris, France

Slides MOPP115 [1.405 MB]

TUIOA02

R&D Efforts for ERLs

linac, emittance, cavity, operation

394

R.G. Eichhorn
Cornell University, Ithaca, New York, USA

The last few years has seen extensive R&D for ERLs, with several prototype facilities now under construction or in operation. The Cornell ERL R&D program has reached major goals, with producing the world’s brightest beam from any photoinjector, reaching CW beam current of greaters than 75 mA, and reaching intrinsic quality factors of 10¹¹ in an SRF cavity installed in a cryomodule. The talk gives an overview of status of ERLs projects, and ERL R&D.

Slides TUIOA02 [8.803 MB]

TUIOC03

Nb3Sn - Present Status and Potential as an Alternative SRF Material

cavity, niobium, linac, cryogenics

431

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

Nb₃Sn is a material that has the potential to have a transformative impact on SRF linacs. Due to its large critical temperature of approximately 18 K, Nb₃Sn cavities can have far smaller surface resistances at a given temperature than standard Nb cavities. This could significantly reduce the costs for infrastructure and power in cryoplants for large CW linacs. In addition, the predicted superheating field of Nb₃Sn is approximately double that of Nb, potentially doubling the maximum energy gradient. This would significantly decrease the size and cost of high energy linacs. In this work, we present recent progress in research and development for this promising material.

Slides TUIOC03 [3.357 MB]

Poster TUIOC03 [2.046 MB]

TUPP002

Commissioning of the 72 MHz Quarter-Wave Cavity Cryomodule at ATLAS

cavity, cryomodule, ion, operation

440

M.P. Kelly, Z.A. Conway, S.M. Gerbick, M. Hendricks, M. Kedzie, S.H. Kim, S.W.T. MacDonald, R.C. Murphy, P.N. Ostroumov, T. Reid, S.I. Sharamentov, G.P. Zinkann
ANL, Argonne, Illinois, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under contract number DE-AC02-06CH11357.
A cryomodule of seven 72 MHz SC quarter-wave cavities optimized for ions with v/c=0.077 has been commissioned in the ATLAS heavy-ion accelerator at Argonne. ATLAS has a new capability for increased beam currents with low beam losses for nuclear physics experiments using stable or rare isotope beams or neutron rich beams from the Californium Rare Isotope Breeder. The main goal for the cryomodule, to provide an accelerating voltage of 17.5 MV (2.5 MV/cavity), with no detectable beam losses has been met within the first month of commissioning. Thus far, cavities and primary subsystems including high-power couplers and pneumatic tuners are operating as designed with full availability. For present levels there is practically no field emission (EPEAK=40 MV/m) and RF losses of ~5 Watts/cavity are only half of that planned. Cavity fields will continue to be gradually increased, with the limits due to cavity quench measured at VACC=3.75 MV. Due to a combination of rf design and cavity processing, effective voltages are now 2 ½ times those for any other operational cavities for this v/c. We report here on the recent online test results and technical features of the present design.

TUPP018

Analysis of Systematic and Random Error in SRF Material Parameter Calculations

simulation, cavity, extraction, niobium

465

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

Funding: NSF Career award PHY-0841213 and DOE award ER41628
To understand the relationship between an RF cavity’s performance and the material on its surface, one must look at various parameters, including energy gap, mean free path, and residual resistance. Though SRIMP fits for seven parameters, three parameters are eliminated using measurement and literature values, and the uncertainty of the fit of the remaining four parameters is further reduced by synthesizing two 3-parameter fits, each from a different data set. To study random error, Monte Carlo simulations were performed of ideal data with added noise; for systematic error, contour plots of normalized residual sum of squares (RSS) of the polymorphic fit on inputted data were generated.

Poster TUPP018 [1.183 MB]

TUPP040

Preliminary Functional Analysis of ESS Superconducting Radio-Frequency Linac

cryomodule, vacuum, controls, interface

522

C. Darve, N. Elias, J. Fydrych, D.P. Piso
ESS, Lund, Sweden

The European Spallation Source (ESS) is one of Europe's largest planned research infrastructures. The collaborative project is funded by a collaboration of 17 European countries and is under design and construction in Lund, Sweden. Three families of Superconducting Radio-Frequency (SRF) cavities are being prototyped, counting the spoke resonators with a geometric beta of 0.5, medium-beta elliptical cavities (βg=0.67) and high-beta elliptical cavities (bg=0.86). The 5 MW, 2.86 ms long pulse proton accelerator has a repetition frequency of 14 Hz (4 % duty cycle), and a beam current of 62.5 mA. The cavities and power couplers are assembled into cryomodules, which are operating using RF sources, cryogenic and water coolings. This document describes the process of the ESS SRF cryomodule operation while refereeing to operational modes.

TUPP052

SSR1 Tuner Mechanism: Passive and Active Device

cavity, cryomodule, alignment, operation

541

D. Passarelli
Fermilab, Batavia, Illinois, USA

In this paper we present the methodology adopted in designing the mechanism responsible for controlling the resonant frequency of Single Spoke Resonators of first type (SSR1). Such device is capable of compensating the effects of external perturbations, such as pressure fluctuations and microphonics, on the frequency of SSR1. The compensation is achieved through active responses via an actuation system and passive responses which are inherent to the elastic behavior of the overall system. The first experiences in the design, assembly, QA and testing are reported.

Poster TUPP052 [2.368 MB]

TUPP055

Progress on Euclid SRF Conical Half-Wave Resonator Project

cavity, niobium, vacuum, proton

547

E.N. Zaplatin
FZJ, Jülich, Germany
T.L. Grimm
Niowave, Inc., Lansing, Michigan, USA
A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: This Work is supported by the DOE SBIR Program, contract # DE-SC0006302.
Euclid conical Half-Wave Resonator (cHWR) project develops 162.5 MHz β=v/c=0.11 accelerator structure for the high-intensity proton accelerator complex proposed at Fermi National Accelerator Laboratory. The main idea of this project is to provide a self-compensation cavity design together with its helium vessel to minimize the resonant frequency dependence on external loads. A unique cavity side-tuning option is also under development. Niowave, Inc. proposed a complete cavity production procedure including preparation of technical drawings, processing steps and resonator high-gradient tests to demonstrate such possibility for the private company. Here we present the procedure of the cavity and helium vessel fabrication, cavity preparation and initial experimental results.

TUPP065

RF Input Power Couplers for High Current SRF Applications

cavity, booster, linac, simulation

575

V.F. Khan, W. Anders, A. Burrill, J. Knobloch, O. Kugeler, A. Neumann
HZB, Berlin, Germany
H. Wang
JLab, Newport News, Virginia, USA

High current SRF technology is being explored in present day accelerator science. The BERLinPro project is presently being built at the HZB to address the challenges involved in high current SRF machines. A 100 mA electron beam is designed to be accelerated to 50 MeV in continuous wave (cw) mode at 1.3 GHz. One of the main challenges in this project is that of handling high input RF power for the gun as well as booster cavities where there is no energy recovery process. A high power co-axial input coupler is being developed to be used for the booster and gun cavities at the nominal beam current. The coupler is based on the KEK–cERL coupler design. The KEK coupler design has been modified to minimise the penetration of the tip in the beampipe without compromising on beam-power coupling ( Qext ~1 x 105). Herein we report on the RF design for the high power (130 kW) BERLinPro (BP) couplers along with the test stand for conditioning the couplers. We will also report on the RF conditioning of the TTF-III couplers modified for cw operation (low power ~ 10 kW) which will be utilised in a new 4-mA SRF Photoinjector and the BERLinPro main linac cryomodule.

Slides TUPP065 [2.465 MB]

TUPP066

Commissioning Results of the 2nd 3.5 Cell SRF Gun for ELBE

gun, cavity, electron, solenoid

578

A. Arnold, M. Freitag, P. Murcek, J. Teichert, H. Vennekate, R. Xiang
HZDR, Dresden, Germany
G. Ciovati, P. Kneisel, L. Turlington
JLab, Newport News, Virginia, USA

As in 2007 the first 3.5 cell superconducting radio frequency (SRF) gun was taken into operation at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), it turned out that the specified performance to realize an electron energy gain of 9.4 MeV (Epk=50 MV/m @ Q0=10¹⁰) has not been achieved. Instead, the resonator of the gun was limited by field emission to about one third of these values and the measured beam parameters remained significantly behind the expectations. However, to demonstrate the full potential of this new electron source for the ELBE LINAC, a second and slightly modified SRF gun was developed and built in collaboration with Thomas Jefferson National Accelerator Facility (TJNAF). We will report on commissioning and first results of this new SRF gun. This includes in particular the characterization of the most important RF properties of the cavity as well as their comparison with previous vertical test results.

Poster TUPP066 [1.220 MB]

TUPP068

New SRF Facility at KEK for Mass-Production Study in Collaboration with Industries

cryomodule, cavity, operation, cryogenics

584

H. Hayano
KEK, Ibaraki, Japan

The construction of the new SRF facility next to the KEK-STF facility has started from 2014 for the mass-production study of SRF accelerators in collaboration with industries. The new building for this facility has the dimension of 80 m x 30 m, and the plan is to install clean-room for cavity-string assembly, cryomodule-assembly facility, cryogenic system, vertical test facility, cryomodule test facility, input coupler process facility, cavity Electro-Polishing (EP) facility, and control-room/office-rooms in it. The purpose of this new SRF facility is to establish a close collaboration between SRF researchers and industries in order to prepare for the upcoming large-scale future SRF project, like ILC. This paper describes the infra-structure detail and the plan to utilize for future SRF accelerators.

TUPP083

Design and Analysis of Slow Tuner in the Superconducting Cavity of RISP

cavity, superconducting-cavity, niobium, target

616

M.O. Hyun, H.C. Jung, H.J. Kim
IBS, Daejeon, Republic of Korea

Funding: This work was supported by the Rare Isotope Science Project of Institute of Basic Science funded by the Ministry of Science, ICT and Future Planning and National Research Foundation.
Superconducting cavity is one of the most complex systems from the view of mechanical engineering, which is installed and operated in the superconducting linear accelerator. In order to operate SC cavity properly and precisely, superconducting cavity needs many sub-systems, including power coupler for applying RF power inside cavity, and liquid helium jacket for cooling cavity until reaching to the superconducting conditions. And, also cavity needs frequency tuning system for adjusting operating frequency when RF frequency of cavity is changed with outer disturbances such as liquid helium fluctuation, mechanical deformation due to vacuum condition of cavity. Generally, this tuning system is called as a tuner. There are two types of tuner, one is slow tuner which operates with motor, and the other is fast tuner which operates with piezo-electric actuator. This paper describes about design process and analysis results about slow tuner.

TUPP086

RAON Superconducting Radio Frequency Test Facility Construction

cavity, radiation, cryogenics, electron

625

H. Kim, D. Jeon, Y.W. Jo, Y. Jung, S.A. Kim, W.K. Kim, S.J. Lee, S.W. Nam, G.-T. Park, J.H. Shin
IBS, Daejeon, Republic of Korea

Superconducting Radio Frequency (SRF) test facility for RAON is under construction process. It consists of cryogenic system, clean room for cavity process and assembles vertical test, horizontal test, and the radiation shield. The cryoplant has 330 W (4.5 K equivalent) which supplies 4.5K supercritical helium to the cavity test and cryomodule test bench. Clean rooms are for cavity process and assemble whose class is from 10 to 10000. The layout for the vertical and horizontal test bench is shown and the radiation shield for the test bench is shown to reduce X-ray coming from cavity. To estimate the thickness of concrete, radiation simulation is performed.

TUPP138

Analysis of New High-Q0 SRF Cavity Tests by Nitrogen Gas Doping at Jefferson Lab

cavity, injection, niobium, vacuum

736

A.D. Palczewski, R.L. Geng, C.E. Reece
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
In order to refine systematic understanding and establish confident process control, Jefferson Lab has joined with partners to investigate and thoroughly characterize the dramatically higher Q0 of 1.3 GHz niobium cavities first reported by FNAL in 2013[1]. With partial support from the LCLS-II project, JLab has undertaken a parametric study of nitrogen doping in vacuum furnace at 800 C followed by variable depth surface removal in the 5 - 20 μm range. Q0 above 3×10¹⁰ are typical at 2.0 K and 16 MV/m accelerating field. We report observations from the single cell study and current interpretations. In addition to the parametric single cell study, we also report on the ongoing serial testing of six nitrogen-doped 9-cell cavities as baseline prototypes for LCLS-II.
[1] A. Grassellino, et al., Supercon. Sci.and Tech., 2013. 26(10): p. 102001

Poster TUPP138 [4.214 MB]

WEIOA06

Low Level RF for SRF Accelerators

LLRF, cavity, controls, operation

760

J. Branlard
DESY, Hamburg, Germany

Low level radio frequency (LLRF) systems are a fundamental component of superconducting RF accelerators. Since the release of the MicroTCA standard (MTCA.4), major developments in MTCA.4-based LLRF systems have taken place. State-of-the-art LLRF designs deliver better than 10^-4 relative amplitude and 10 mdeg phase stability for the vector sum control of SRF cavities. These developments in LLRF systems architecture and technology, driven by research institutes and supported by the industry are of highest importance for the European XFEL, but also for other SRF-based projects such as LCLS-II and the ESS, as well as for the next generation accelerators with 10-5 and mdeg regulation requirements.

Slides WEIOA06 [5.812 MB]

THIOA02

Superconducting RF Development for FRIB at MSU

cavity, cryomodule, solenoid, operation

790

K. Saito, N.K. Bultman, E.E. Burkhardt, F. Casagrande, S.K. Chandrasekaran, S. Chouhan, C. Compton, J.L. Crisp, K. Elliott, A. Facco, A.D. Fox, P.E. Gibson, M.J. Johnson, G. Kiupel, R.E. Laxdal, M. Leitner, S.M. Lidia, 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, T. Russo, S. Shanab, M. Shuptar, S. Stark, N.R. Usher, G.J. Velianoff, D.R. Victory, J. Wei, G. Wu, X. Wu, T. Xu, T. Xu, Y. Yamazaki, Q. Zhao, Z. Zheng
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.
FRIB is a $730M heavy ion accelerator project and a very large scale machine for many nuclear physics users. The civil construction started on March 17th 2014. The SRF system design and development have completed. The machine is to be in early completion end of 2019. FRIB accelerates ion species up to 238U with energies of no less than 200MeV/u and provides a beam power up to 400kW. Four SRF cavity families are used from β=0.041, 0.085 (QWRs) to 0.29 and 0.53 (HWRs). 8T superconducting solenoids are installed in the cryomodules for space effective strong beam focusing. The biggest challenges are in accelerating the high-power heavy ion beams from the very low energy to medium energy and the stable operation for large user community. The SRF cryomodule design addressed three critical issues: high performance, stable operation and easy maintainability, which chose several unique technical strategies, e.g.2K operation, bottom up cryomodule assembly, local magnetic shielding and so on. This talk will include high performance cavity R&D, local magnetic shielding, flux trapping by solenoid fringe field, and bottom up cryomodule assembly.

Slides THIOA02 [5.049 MB]

THIOB01

Cryogenic Plants for SRF Linacs

vacuum, cryomodule, linac, cryogenics

811

D. Arenius
JLab, Newport News, Virginia, USA

Review of the types of considerations that go into cryo-plant design. Arenius is a world expert on this topic and has led the completion of the upgraded cryo-plant at Jefferson Lab, and has recently provided substantial input on this question to the new LCLS II project.

Slides THIOB01 [4.382 MB]

THPP016

Nitrogen-Treated Cavity Testing at Cornell

cavity, niobium, linac, vacuum

866

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

Funding: U.S. Department of Energy
Recent results from Cornell, FNAL, and TJNAF have shown that superconducting RF cavities given a heat treatment in a nitrogen atmosphere show higher Q₀ at operating gradients at 2.0 K than standard SRF cavities. Here we present on recent results at Cornell in which five single cell cavities and three 9-cell cavities were tested after receiving various nitrogen-doping treatments. Cavity performance was correlated with treatment, and samples treated with the cavities were analyzed with SIMS. These results provide new insights into the science behind the excellent performance that is observed in these cavities.

THPP018

Sample Plate Studies Using a High Field TE Cavity With Thermometry Mapping System

cavity, niobium, coupling, experiment

873

D.L. Hall, C.D. Burton, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: NSF Career Grant PHY-0841213
A TE-Mode sample plate cavity capable of sustaining peak fields of >90 mT on the surface of a 10cm diameter sample plate has been developed and tested at Cornell. A thermometry mapping system composed of 40 Allen-Bradley resistors, mounted on the outside of the sample plate, is capable of measuring the surface resistance of the sample with a resolution of 1 nOhm and a spatial resolution of 0.5 cm. In this paper we present the design and expected performance of this high field TE cavity, and show data taken with a sample plate of niobium as well as results from tests qualifying the performance of the thermometry mapping system.

THPP021

Analysis of the RF Test Results from the On-going Accelerator Cavity Production for the European XFEL

cavity, superconductivity, linac, operation

879

D. Reschke, S. Aderhold, V. Gubarev, J. Schaffran, N.J. Walker
DESY, Hamburg, Germany
L. Monaco
INFN/LASA, Segrate (MI), Italy
Y. Yamamoto
KEK, Ibaraki, Japan

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 superconducting accelerator modules, operated at an average design gradient of 23.6 MV/m. The fabrication by industry (which includes chemical surface preparation) of the required 800 superconducting cavities is now in full swing, with approximately 400 cavities having been delivered to date. In this interim report, we present an analysis of the RF acceptance tests amassed so far.

THPP031

Plans for an ERL Test Facility at CERN

cavity, cryomodule, electron, linac

905

E. Jensen, O.S. Brüning, R. Calaga, K.M. Schirm, R. Torres-Sanchez, A. Valloni
CERN, Geneva, Switzerland
K. Aulenbacher
IKP, Mainz, Germany
S.A. Bogacz, A. Hutton
JLab, Newport News, Virginia, USA
M. Klein
The University of Liverpool, Liverpool, United Kingdom

The baseline electron accelerator for LHeC and one option for FCC-he is an Energy Recovery Linac. To prepare and study the necessary key technologies, CERN has started – in collaboration with JLAB and Mainz University – the conceptual design of an ERL Test Facility (ERL-TF). Staged construction will allow the study under different conditions with up to 3 passes, beam energies of up to about 1 GeV and currents of up to 50 mA. The design and development of superconducting cavity modules, including coupler and HOM damper designs, are also of central importance for other existing and future accelerators and their tests are at the heart of the current ERL-TF goals. The ERL-TF could also provide a unique infrastructure for several applications that go beyond developing and testing the ERL technology at CERN. In addition to experimental studies of beam dynamics, operational and reliability issues in an ERL, it could equally serve for quench tests of superconducting magnets, as physics experimental facility on its own right or as test stand for detector developments. This contribution will describe the goals and the concept of the facility and the status of the R&D.

THPP046

SRF Highbay Technical Infrastructure for FRIB Production at Michigan State University

cavity, cryomodule, vacuum, controls

954

L. Popielarski, F. Casagrande, C. Compton, T. Elkin, A. Fila, P.E. Gibson, M. Hodek, L. Hodges, I.M. Malloch, C. Nguyen, R. Oweiss, J.P. Ozelis, J. Popielarski, C. Thronson, D.R. Victory, T. Xu
FRIB, East Lansing, Michigan, USA
M. Leitner
LBNL, Berkeley, California, USA

Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE- SC0000661
Michigan State University (MSU) has funded the construction of a new 27,000 square foot high bay building to house the Superconducting Radio Frequency (SRF) infrastructure for the Facility for Rare Isotope Beams (FRIB) production requirements. The construction has been completed and beneficial occupancy began on May 19th, 2014. The new SRF highbay includes over 4,000 square feet of cleanroom and chemistry facility space, automated cavity etch tools, ultra pure water systems, cold mass component inspection area, hydrogen degassing furnace, SRF testing capabilities for three vertical test Dewars and two horizontal cryomodule test bunkers with dedicated helium refrigeration system. The status of the technical equipment design, installation and commissioning will be presented.

THPP048

Design of a Compact Lever Slow/Fast Tuner for 650 MHz Cavities for Project X

cavity, operation, resonance, simulation

957

I.V. Gonin, E. Borissov, T.N. Khabiboulline, Y.M. Pischalnikov, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Fermilab is developing 5-cell elliptical 650 MHz β=0.6 and β=0.9 cavities for Project X. A compact fast/slow lever tuner intended for both types of cavities has been developed for final tuning of the resonance frequency of the cavity after cooling down and to compensate the resonance frequency variations of the cavity during operation coming from liquid helium pressure fluctuations. The updated helium vessel (presented at this conference) is equipped with the tuner located at one of the end of the cavity. The tuner design and results of ANSYS analysis of their properties are presented.

THPP057

Results of Cold Tests of the Fermilab SSR1 Cavities

cavity, cryomodule, radiation, resonance

979

A.I. Sukhanov, M.H. Awida, P. Berrutti, E. Cullerton, B.M. Hanna, A. Hocker, T.N. Khabiboulline, O.S. Melnychuk, D. Passarelli, R.V. Pilipenko, Y.M. Pischalnikov, L. Ristori, A.M. Rowe, W. Schappert, D.A. Sergatskov
Fermilab, Batavia, Illinois, USA

Fermilab is currently building the Project X Injector experiment (PXIE). The PXIE linac will accelerate a 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. We discuss tests of nine bare SSR1 cavities at the Fermilab Vertical Test Stand (VTS). Recently, one of the SSR1 cavities was welded inside a helium jacket. Results of the test of this cavity in the Fermilab Spoke Test Cryostat (STC) are shown. We report on the measured performance parameters of SSR1 cavities achieved during the tests.

THPP062

BERLinPro SRF Gun Notch Filter Investigations

gun, cathode, cavity, resonance

995

E.N. Zaplatin
FZJ, Jülich, Germany
J. Knobloch, A. Neumann
HZB, Berlin, Germany

BERLinPro is an approved ERL project to demonstrate energy recovery at 100 mA beam current by pertaining a high quality beam. These goals place stringent requirements on the SRF cavity (1300 MHz, β=1) for the photoinjector which has to deliver a small emittance 100 mA beam with at least 1.8 MeV kinetic energy while limited by fundamental power coupler performance to about 230 kW forward power. The RF and beam dynamics gun cavity features 1.4 λ/2 cell resonator. To protect a cathode housing from RF power propagation from the cavity cells and to reduce its component heating a high-frequency notch filter was investigated. We present results of different schemes of choke cell combinations to optimize filter parameters. The goal for the filter design was the RF power attenuation better than -30 dB in the wide frequency range.

THPP072

BERLinPro Booster Cavity Design, Fabrication and Test Plans

cavity, cryomodule, booster, linac

1019

A. Burrill, W. Anders, A. Frahm, J. Knobloch, A. Neumann
HZB, Berlin, Germany
G. Ciovati, P. Kneisel, L. Turlington
JLab, Newport News, Virginia, USA

The BERLinPro project, a 100 mA, 50 MeV superconducting RF (SRF) Energy Recovery Linac (ERL) is under construction at Helmholtz-Zentrum Berlin for the purpose of studying the technical challenges and physics of operating a high current, c.w., 1.3 GHz ERL. This machine will utilize three unique SRF cryomodules for the injector, booster and linac module respectively. The booster cryomodule will contain three 2-cell SRF cavities, based on the original design by Cornell University, and will be equipped with twin 115 kW RF power couplers in order to provide the appropriate acceleration to the high current electron beam. This paper will review the status of the fabrication of the 4 booster cavities that have been built for this project by Jefferson Laboratory and look at the challenges presented by the incorporation of fundamental power couplers capable of delivering 115 kW. The test plan for the cavities and couplers will be given along with a brief overview of the cryomodule design.

THPP077

Fast Tuner Performance for a Double Spoke Cavity

cavity, operation, simulation, controls

1034

N. Gandolfo, S. Bousson, S. Brault, P. Duchesne, P. Duthil, G. Olry, D. Reynet
IPN, Orsay, France
C. Darve, M. Lindroos
ESS, Lund, Sweden

IPN Orsay is developing the low-beta double Spoke cavities cryomodule for the ESS. In order to compensate resonant frequency variations of each cavity during operation, a deformation tuner has been studied and two of them have been built. The typical perturbations are coming from LHe saturated bath pressure variations as well as microphonics and Lorentz force detuning (LFD). In this paper, the tuner performance of the double Spoke cavity is presented.

THPP107

Study on Polishing Method of Nb Surface by Periodic Reverse Current Electrolysis With Alkali Solution

experiment, cavity, laser, operation

1102

M. Umehara
Nomura Plating Co, Ltd., Osaka, Japan
H. Hayano, T. Saeki
KEK, Ibaraki, Japan

Currently, electropolising method is thought to be the best method for the final surface preparation of superconducting RF cavity to obtain high gradient. In this conventional electropolising method, the electrolyte is the mixture of fluoric and sulfuric acids. Therefore, the operation of this method is dangerous, and the equipment becomes expensive because all parts should be made of high density polyethylene or fluorocarbon resin to avoid metallic parts which suffers from corrosion by electrolyte. Moreover, sulfur is produced as byproduct in the electropolishing process and this causes degradation of cavity performance. In order to overcome these drawbacks, we studied new polishing method of Nb surface by periodic reverse current electrolysis with alkali solution which causes no sulfur and allows the usage of metallic parts to realize cost effective equipment. In the study, we performed experiment of Nb coupons by this new method and obtained as good surface roughness as conventional electropolishing method. In this article, we report the details of the study.

THPP135

Recent Improvements to Software Used for Optimization of SRF Linacs

cryomodule, cavity, linac, cryogenics

1174

T. Powers
JLab, Newport News, Virginia, USA

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
This work describes a 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 program includes estimates for the associated cryogenic facility, and controls hardware, where operation costs includes the cost of the electrical utilities but not the labor or other costs. The software interface provides the ability to vary the cost of the different aspects of the machine as well as to change the cryomodule and cavity types. Additionally, this work will describe the recent improvements to the software that allow one to estimate the costs of energy recovery based linacs and to enter arbitrary values of the low field Qo and Qo slope. The initial goal was to convert a spreadsheet 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. An example of how it was used to investigate the cost optimization tradeoffs for the LCLS 2 linac will also be presented.