WEPWI —  Wednesday Posters (Wilson)   (06-May-15   16:00—18:00)

Paper	Title	Page
WEPWI001	An Overview of the MaRIE X-FEL and Electron Radiography Linac RF Systems	3482
	J.T. Bradley III, D. Rees, A. Scheinker, R.L. Sheffield LANL, Los Alamos, New Mexico, USA
	The purpose of the Matter-Radiation Interactions in Extremes (MaRIE) facility at Los Alamos National Laboratory is to investigate the performance limits of materials in extreme environments. The MaRIE facility will utilize a 12 GeV linac to drive an X-ray FEL. Most of the same linac will also be used to perform electron radiography. The main linac is driven by two shorter linacs; one short linac optimized for X-FEL pulses and one for electron radiography. The RF systems have historically been the one of the largest single component costs of a linac. We will describe the details of the different types of RF systems required by each part of the linacs. Starting with the High Power RF system, we will present our methodology for the choice of RF system peak power and pulselength with respect to klystrons parameters, modulator parameters, performance requirements and relative costs. We will also present an overview of the low level RF systems that are proposed for MaRIE and briefly describe their use with some proposed control schemes. * * A. Scheinker, "Adaptive Accelerator Tuning", Proc. of IPAC'15.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI001
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WEPWI002	Installation and Operation of Replacement 201 MHz High Power RF System at LANSCE	3485
	J.T.M. Lyles, W.C. Barkley, J. Davis, D. Rees, G. M. Sandoval, Jr. LANL, Los Alamos, New Mexico, USA R.E. Bratton, R.D. Summers Compa Industries, Inc., Los Alamos, New Mexico, USA
	Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-­-AC52-­-06NA25396. The LANSCE RM project has restored the linac to high power capability after the power tube manufacturer could no longer provide triodes that consistently met our high average power requirement. Diacrodes® now supply RF power to two of the four DTL tanks. These tetrodes reuse the existing infrastructure including water-cooling systems, coaxial transmission lines, high voltage power supplies and capacitor banks. The power amplifier system uses a combined pair of LANL-designed cavity amplifiers using the TH628L Diacrode® to produce up to 3.5 MW peak and 420 kW of mean power. Design and prototype testing was completed in 2012, with commercialization following in 2013. The first installation was completed in 2014 and a second installed system is ready to test. The remaining replacement will follow in 2016. Meanwhile, there is a hybrid of old/new amplifiers until the changeover is complete. Operating results of the replacement system are summarized, along with observations from the rapid-­-paced installation project.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI002
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WEPWI003	Design of a Radial Klystron	3489
	M. Dal Forno, A. Jensen, R.D. Ruth, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: Work supported by the US DOE under contract DEAC03-76SF00515. The radial klystron is a multidimensional rf source where the beam is generated by a cylindrical gun and it propagates in the radial dimension. The advantage of this design is that the space charge effects are balanced in the azimuthal dimension and a lower magnetic fields is required to focus the electron beam. The bunching is made with concentric coaxial resonators, connected by drift tube. The electron beam interaction with the cavity fields has been analyzed by means of particle tracking software in order to evaluate the beam bunching and the beam dynamics. This paper shows the klystron design, optimizing the shape and the position of each cavity, in order to maximize the efficiency of the device.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI003
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WEPWI004	FPC and Hi-Pass Filter HOM Coupler Design for the RF Dipole Crab Cavity for the LHC HiLumi Upgrade	3492
	Z. Li SLAC, Menlo Park, California, USA S.U. De Silva, J.R. Delayen, R.G. Olave, H. Park ODU, Norfolk, Virginia, USA
	Funding: Work partially supported by the US DOE through the US LHC Accelerator Research Program (LARP), and by US DOE under contract number DE-AC02-76SF00515. A 400-MHz compact RF dipole (RFD) crab cavity design was jointly developed by Old Dominion University and SLAC under the support of US LARP program for the LHC HiLumi upgrade. The RFD cavity design is consisted of a rounded-square tank and two ridged deflecting poles, operating with a TE11-like dipole mode, which is the lowest mode of the cavity. A prototype RFD cavity is being manufactured and will be tested on the SPS beam line at CERN. The coaxial fundamental Power Coupler (FPC) of the prototype cavity was re-optimized to minimizing the power heating on the coupler internal antenna. A hi-pass filter HOM damping coupler was developed to achieve the required wakefield damping while maintaining a compact size to fit into the beam line space. In this paper, we will discuss the details of the RF optimization and tolerance analyses of the FPC and HOM couplers.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI004
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WEPWI005	Novel Approach to Variable Voltage Substation Protection	3496
	M.Y. Mehtabuddin, C. Jach, S. Olek SLAC, Menlo Park, California, USA
	Conventional electrical system protection of variable voltage substations(medium voltage rated) of using fuses and phase overcurrent and/or phase time overcurrent protection is not adequate. This was evident from the recent variable voltage substation (VVS) electrical fire at SLAC. Using information obtained from the fire investigation, ETAP simulations, and event reports of the faults which led to the fire, SLAC put into action a fast, feasible, and economical relay protection plan into adequately protecting VVS until long term plan of replacements is implemented. The plan utilizes the existing microprocessor protection relays on the upstream vacuum breakers and included the following adjustments: Adjusting the long time overcurrent according to the de-rated cable ampacities, dual-fed arc flash fault protection, adding negative sequence settings and relay control logic to allow for two sets of settings for inrush mode and normal mode.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI005
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WEPWI006	Dither Coils for the SuperKEKB Fast Collision Feedback System	3500
	U. Wienands, S.D. Anderson, S.M. Gierman, M. Kosovsky, C.M. Spencer, M.K. Sullivan SLAC, Menlo Park, California, USA Y. Funakoshi, M. Masuzawa, T. Oki KEK, Ibaraki, Japan
	Funding: Work supported in part by US DOE and in part by the US-Japan collaboration agreement. The collision feedback system for the SuperKEKB electron-positron collider at KEK will employ a dither feedback with a roughly 100 Hz excitation frequency to generate a signal proportional to the offset of the two beams. The excitation will be provided by a local bump across the interaction point (IP) that is generated by a set of eight air-core solid-wire magnet coil assemblies, each of which provides a horizontal and/or vertical deflection of the beam, to be installed around the vacuum system of the SuperKEKB Low Energy Ring. The design of the coils was challenging as large antechambers had to be accommodated and a 0.1% relative field uniformity across a good-field region of ±1 cm was aimed for, while keeping reasonable dimensions of the coils. This led to non-symmetric, non-flat designs of the coils. The paper describes the magnetic design and the method used to calculate the magnetic field of the coils, the mechanical design and the field measurement results. Tracking in the lattice model has indicated acceptable performance.
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WEPWI007	TTF3 Power Coupler Thermal Analysis for LCLS-II CW Operation	3503
	L. Xiao, C. Adolphsen, Z. Li, C.D. Nantista, T.O. Raubenheimer SLAC, Menlo Park, California, USA I.V. Gonin, N. Solyak Fermilab, Batavia, Illinois, USA
	The TESLA 9-cell SRF cavity design has been adopted for use in the LCLS-II SRF Linac. Its TTF3 coaxial Fundamental Power Coupler (FPC), developed for pulsed operation in the European XFEL and ILC, requires modest changes to make it suitable for LCLS-II CW operation, in which it must be able to handle up to 7 kW of average power with the maximum temperature rise not to exceed 150 C. In order to improve TTF3 FPC cooling, an increased copper plating thickness will be used on the inner and outer conductor stainless steel RF surfaces. Fully 3D FPC thermal analysis with copper plating was performed using the SLAC developed parallel finite element code suite ACE3P with integrated electromagnetic, thermal and mechanical multi-physics simulation capabilities. In this paper, we present TTF3 FPC thermal analysis simulation results obtained using ACE3P as well as a comparison with measurement results.
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WEPWI009	Nitrogen Doping Study in Ingot Niobium Cavities	3506
	P. Dhakal, G. Ciovati, P. Kneisel, G.R. Myneni JLab, Newport News, Virginia, USA J. Makita ODU, Norfolk, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 Thermal diffusion of nitrogen in superconducting radio frequency cavities at temperatures around 800C has resulted in the increase in quality factor with a low-field Q-rise. However, the maximum accelerating gradients of these doped cavities often reduces below the values achieved by standard treatments. In this contribution, we present the results of the nitrogen diffusion into ingot niobium cavities subjected to successive material removal from the inner cavity surface by electropolishing in an effort to explore the underlying cause for the gradient degradation.
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WEPWI010	Results from the First Single Cell Nb3Sn Cavity Coatings at JLab	3509
	G.V. Eremeev JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Nb3Sn is a promising superconducting material for SRF applications and has the potential to exceed the limitations of niobium. We have used the recently commissioned Nb3Sn coating system to investigate Nb3Sn coatings on several single cell cavities by applying the same coating procedure on several different single cells with different history and pre-coating surface preparation. We report on our findings with four 1.5 GHz CEBAF-shape single cell and one 1.3 GHz ILC-shape single cavities that were coated, inspected, and tested.
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WEPWI011	Commissioning Results of Nb3Sn Cavity Vapor Diffusion Deposition System at JLab	3512
	G.V. Eremeev, W.A. Clemens, K. Macha, H. Park, R.S. Williams JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Nb3Sn as a BCS superconductors with a superconducting critical temperature higher than that of niobium offers potential benefit in lower surface resistance at the same temperature and frequency for SRF cavities. A Nb3Sn vapor diffusion deposition system was built and commissioned at Jefferson Lab. As the part of the commissioning a single cell 1.5 GHz CEBAF-shaped cavity was coated in the built system. The cavity exhibited the superconducting transition at about 17.9 K. The low field quality factor was about 5x109 at 4 K and 7x109 at 2 K dropping with field to about 109 at both temperatures at about 8 MV/m.
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WEPWI012	First Attempt of At-cavity X-ray Detection in a CEBAF Cryomodule for Field Emission Monitoring	3515
	R.L. Geng, E. Daly, M.A. Drury, A.D. Palczewski JLab, Newport News, Virginia, USA
	We report on the first result of at-cavity X-ray detection in a CEBAF cryomodule for field emission monitoring. In the 8-cavity cryomodule F100, two silicon diodes were installed near the end flange of each cavity. Each cavity was individually tested during the cryomodule test in JLab’s cryomodule test facility. The behaviors of these at-cavity cryogenic X-ray detectors were compared with those of the standard “in air” Geiger-Muller tubes. Our initial experiments establish correlation between X-ray response of near diodes and the field emission source cavity in the 8-cavity string. For two out of these eight cavities, we also carried out at-cavity X-ray detection experiment during their vertical testing. The aim is to track field emission behavior uniquely from vertical cavity testing to horizontal cavity testing in the cryomodule.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI012
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WEPWI013	New Results of Development on High Efficiency High Gradient Superconducting RF Cavities	3518
	R.L. Geng JLab, Newport News, Virginia, USA C. Adolphsen, Z. Li SLAC, Menlo Park, California, USA J.K. Hao, K.X. Liu PKU, Beijing, People's Republic of China H.Y. Zhao Ningxia Orient Tantalum Industry Co., Ltd., Dawukou District, Shizuishan city, People's Republic of China
	We report on the latest results of development on high efficiency high gradient superconducting radio frequency (SRF) cavities. Several 1-cell cavities made of large-grain niobium (Nb) were built, processed and tested. Two of these cavities are of the Low Surface Field (LSF) shape. Series of tests were carried out following controlled thermal cycling. Experiments toward zero-field cooling were carried out. The best experimentally achieved results are Eacc = 41 MV/m at Q0 = 6.5×1010 at 1.4 K by a 1-cell 1.3 GHz large-grain Nb TTF shape cavity and Eacc = 49 MV/m at Q0 = 1.5×1010 at 1.8 K by a 1-cell 1.5 GHz large-grain Nb CEBAF upgrade low-loss shape cavity.
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WEPWI015	BNL 56 MHz HOM Damper Prototype Fabrication at JLab	3521
	N.A. Huque, W.A. Clemens, E. Daly JLab, Newport News, Virginia, USA S. Bellavia, G.T. McIntyre, S.K. Seberg, Q. Wu BNL, Upton, Long Island, New York, USA
	A prototype Higher-Order Mode (HOM) Damper was fabricated at JLab for the Relativistic Heavy-Ion Collider’s (RHIC) 56 MHz cavity at Brookhaven National Laboratory (BNL). Primarily constructed from high RRR Niobium and Sapphire, the coaxial damper presented significant challenges in electron-beam welding (EBW), brazing and machining via acid etching. The results of the prototype operation brought about changes in the damper design, due to overheating braze alloys and possible multi-pacting. Five production HOM dampers are currently being fabricated at JLab. This paper outlines the challenges faced in the fabrication process, and the solutions put in place.
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WEPWI016	Investigation of Differential Surface Removal due to Electropolishing at JLab	3525
	F. Marhauser, J. Follkie, C.E. Reece JLab, Newport News, Virginia, USA
	Surface chemistry carried out for Superconducting Radio Frequency (SRF) cavities such as Buffered Chemical Polishing (BCP) and Electropolishing (EP) aims to uniformly remove the internal surface of a cavity along the entire structure and within each cell from equator to iris in order to obtain an equally etched surface. A uniform removal however is not readily achievable due to the complex fluid flow and varying temperatures of the acid mixture, which can lead to differential etching. This needs to be considered when envisaging a certain surface damage removal throughout the interior. The process-specific differential etching influences the target frequency set at the manufacturing stage as well as the field flatness and length of the as-built cavity. We report on analyses of JLab's present EP system using experimental data for six nine-cell cavities that have been processed recently in the frame of the LCLS-II high-Q development plan. In conjunction with numerical simulations, the differential etching and the impact on field flatness is assessed.
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WEPWI019	Quench Studies of Six High Temperature Nitrogen Doped 9 Cell Cavities for Use in the LCLS-II Baseline Prototype Cryo-module at Jefferson Laboratory	3528
	A.D. Palczewski, G.V. Eremeev, 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. Jefferson Lab (JLab) processed six nine-cell cavities as part of a small-scale production for LCLS-II cavity processing development utilizing the promising nitrogen-doping process. [1] Various nitrogen-doping recipes have been scrutinized to optimize process parameters with the aim to guarantee an unloaded quality factor (Q 0) of 2.7·1010 at an accelerating field (Eacc) of 16 MV/m at 2.0 K in the cryomodule. During the R&D phase the characteristic Q0 vs. Eacc performance curve of the cavities has been measured in JLab’s vertical test area at 2 K. The findings showed the characteristic rise of the Q0 with Eacc as expected from nitrogen-doping. Initially, five cavities achieved an average Q0 of 3.3·1010 at the limiting Eacc averaging to 16.8 MV/m, while one cavity experienced an early quench accompanied by an unusual Q 0 vs. Eacc curve. The project accounts for a cavity performance loss from the vertical dewar test (with or without the helium vessel) to the horizontal performance in a cryomodule, such that these results leave no save margin to the cryomodule specification. Consequently, a refinement of the nitrogen-doping has been initiated to guarantee an average quench field above 20 MV/m without impeding the Q 0. This paper covers the refinement work performed for each cavity, which depends on the initial results, as well as a quench analysis carried out before and after the rework during the vertical RF tests as far as applicable.
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WEPWI021	An Analysis of the Temperature and Field Dependence of the RF Surface Resistance of Nitrogen-Doped Niobium SRF Cavities with Respect to Existing Theoretical Models	3532
	C.E. Reece, A.D. Palczewski JLab, Newport News, Virginia, USA B. P. Xiao BNL, Upton, Long Island, New York, 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 DE-AC05-06OR23177 Recent progress with the reduction of rf surface resistance (Rs) of niobium SRF cavities via the use of high temperature surface doping by nitrogen has opened a new regime for energy efficient accelerator applications. For particular doping conditions one observes dramatic decreases in Rs with increasing surface magnetic fields. The observed variations as a function of temperature may be analyzed in the context of recent theoretical treatments in hopes of gaining insight into the underlying beneficial mechanism of the nitrogen treatment. Systematic data sets of Q0 vs. Eacc vs. temperature acquired during the high Q0 R&D work of the past year will be compared with theoretical model predictions. * * B. P. Xiao et al., Physica C: Superconductivity 490 (0), 26-31 (2013) and A. Gurevich, PRL 113 (8), 087001 (2014)
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WEPWI022	RF System Requirements for a Medium-Energy Electron-Ion Collider (MEIC) at JLab	3536
	R.A. Rimmer, J. Guo, J. Henry, H. Wang, S. Wang JLab, Newport News, Virginia, USA Y.L. Huang IMP/CAS, Lanzhou, People's Republic of China
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 JLab is studying options for a medium energy electron-ion collider that could fit on the JLab site and use CEBAF as a full-energy electron injector. A new ion source, linac and booster would be required, together with collider storage rings for the ions and electrons. In order to achieve the maximum luminosity these will be high current storage rings with many bunches. We present the high level RF system requirements for the storage rings, ion booster ring and high-energy ion beam cooling system, and describe the technology options under consideration to meet them. We also present options for staging that might reduce the initial capital cost while providing a smooth upgrade path to a higher final energy. The technologies under consideration may also be useful for other proposed storage ring colliders or ultimate light sources.
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WEPWI024	Vacuum Characterization and Improvement for the Jefferson Lab Polarized Electron Source	3540
	M.L. Stutzman, P.A. Adderley, M. Poelker JLab, Newport News, Virginia, USA M.A. Mamun Old Dominion University, Norfolk, Virginia, USA
	Operating the JLab polarized electron source with high reliability and long lifetime requires vacuum near the XHV level (<=1x10-12 Torr). This paper describes ongoing vacuum research at Jefferson Lab including characterization of outgassing rates for surface coatings and heat treatments, ultimate pressure measurements, investigation of pumping including an XHV cryopump, and characterization of ionization gauges in this pressure regime.
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WEPWI028	Simulation Study Using an Injection Phase-locked Magnetron as an Alternative Source for SRF Accelerators	3544
	H. Wang, T. E. Plawski, R.A. Rimmer JLab, Newport News, Virginia, USA
	As a drop-in replacement for the CEBAF CW klystron system, a 1497 MHz, CW type high efficiency magnetron using injection phase lock and amplitude variation is attractive. Amplitude control using magnetic field trimming and anode voltage modulation has been studied using analytical models and MATLAB/Simulink simulations. Since the 1497 MHz magnetron has not been built yet, previously measured characteristics of a 2.45GHz cooker magnetron are used as reference. The results of linear responses to the amplitude and phase control of a superconducting RF (SRF) cavity, and the expected overall benefit for the current CEBAF and future MEIC RF systems are presented in this paper.
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WEPWI029	Cavity Design, Fabrication and Test Performance of 750 MHz, 4-Rod Separators for CEBAF 4-Hall Beam Delivery System	3548
	H. Wang, G. Cheng, L. Turlington, M.J. Wissmann JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. A short version of the original CEBAF normal conducting 4-rod separator cavity has been developed into a 750MHz one * since the concept of simultaneous 4-hall operation for CEBAF is introduced **. This work has been advanced further based on the EM design optimization, bench measurement and by conducting RF-thermal coupled simulation using CST and ANSYS to confirm the cavity tuning and thermal performance. The cavity fabrication used matured technology like copper plating and machining. The cavity flanges, couplers, tuners and cooling channels adopted consistent/compatible hardware with the existing 500MHz cavities. The electromagnetic and thermal design simulations have greatly reduced the prototyping and bench tuning time of the first prototype. Four production cavities have reached a typical 1.94MV kick voltage or 3.0kW wall loss on each cavity after a minor multipactoring or no processing, 7.5% overhead power than the design specification. * R. Kazimi et al., IPAC2013, Shanghai, China, pp 2896-2898. ** R. Kazimi, IPAC2013, Shanghai, China, pp 3502-3504.
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WEPWI030	Injector Cavities Fabrication, Vertical Test Performance and Primary Cryomodule Design	3551
	H. Wang, G. Cheng, W.A. Clemens, G.K. Davis, K. Macha, R.B. Overton, D. Spell JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. After the electromagnetic design * and the mechanical design ** of a β=0.6, 2-cell elliptical SRF cavity, the cavity has been fabricated. Then both 2-cell and 7-cell cavities have been bench tuned to the target values of frequency, coupling external Q and field flatness. After buffer chemistry polishing (BCP) and high pressure rinses (HPR), Vertical 2K cavity test results have been satisfied the specifications and ready for the string assembly. We will report the cavity performance including Lorenz Force Detuning (LFD) and Higher Order Modes (HOM) damping data. Its integration with cavity tuners to the cryomodule design will be reported. * H. Wang, etc., Proceeding of IPAC2013, Shanghai, China, WEPWO073. ** G. Cheng, etc., Proceeding of PAC2013, Pasadena, CA, WEPAC47.
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WEPWI032	Mechanical Properties of Niobium Cavities	3554
	G. Ciovati, P. Dhakal, J. Matalevich, G.R. Myneni JLab, Newport News, Virginia, USA
	Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 The mechanical stability of bulk Nb cavity is an important aspect to be considered in relation to cavity material, geometry and treatments. Mechanical properties of Nb are typically obtained from uniaxial tensile tests of small samples. In this contribution we report the results of measurements of the resonant frequency and local strain along the contour of single-cell cavities made of ingot and fine-grain Nb of different purity subjected to increasing uniform differential pressure, up to 6 atm. Measurements have been done on cavities subjected to different heat treatments. Good agreement between finite element analysis simulations and experimental data in the elastic regime was obtained with a single set of values of Young’s modulus and Poisson’s ratio. The experimental results indicate that the yield strength of medium-purity ingot Nb cavities is higher than that of fine-grain, high-purity Nb.
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WEPWI033	Effects of Plasma Processing on Secondary Electron Yield of Niobium Samples	3558
	M. Basovic, S. Popović, M. Tomovic, L. Vušković ODU, Norfolk, Virginia, USA F. Čučkov, A. Samolov University of Massachusetts Boston, Boston, Massachusetts, USA
	Impurities deposited on the surface of Nb during both the forming and welding of accelerator cavities add to the imperfections of the sheet metal, which then affects the overall performance of the cavities. This leads to a drop in the Q factor and limits the maximum acceleration gradient achievable per unit length of the cavities. The performance can be improved either by adjusting the fabrication and preparation parameters, or by mitigating the effects of fabrication and preparation techniques used. We have developed the experimental setup to determine Secondary Electron Yield (SEY) from the surface of Nb samples. Our aim is to show the effect of plasma processing on the SEY of Nb. The setup measures the secondary electron energy distribution at various incident angles as measured between the electron beam and the surface of the sample. The goal is to determine the SEY on non-treated and plasma treated surface of electron beam welded samples. Here we describe the experimental setup, plasma treatment device, and fabrication and processing of the Nb samples.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI033
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WEPWI034	Effects of Crab Cavities' Multipole Content in an Electron-Ion Collider	3561
	A. Castilla, J.R. Delayen, T. Satogata ODU, Norfolk, Virginia, USA A. Castilla, J.R. Delayen, V.S. Morozov, T. Satogata JLab, Newport News, Virginia, USA A. Castilla DCI-UG, León, Mexico
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The impact on the beam dynamics of the Medium Energy Electron-Ion Colider (MEIC) due to the multipole content of the 750 MHz crab cavity was studied using thin multipole elements for 6D phase space particle tracking in ELEGANT. Target values of the sextupole component for the cavity’s field expansion were used to perform preliminary studies on the proton beam stability when compared to the case of pure dipole content of the rf kicks. Finally, important effects on the beam sizes due to non-linear components of the crab cavities’ fields were identified and some criteria for their future study were proposed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI034
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WEPWI035	Beam Dynamics Studies of 499 MHz Superconducting RF-Dipole Deflecting Cavity System	3564
	S.U. De Silva, K.E. Deitrick, J.R. Delayen, H. Park ODU, Norfolk, Virginia, USA
	A 499 MHz deflecting cavity has been designed as a three-way beam spreader to separate an electron beam into 3 beams. The rf tests carried out on the superconducting rf-dipole cavity have demonstrated that a transverse voltage of 4.2 MV can be achieved with a single cavity. This paper discusses the beam dynamics on a deflecting structure operating in continuous-wave mode with a relativistic beam. The study includes the analysis on emittance growth, energy spread, and change in bunch size including effects due to field non-uniformities.
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WEPWI036	Design and Prototyping of a 400 MHz RF-dipole Crabbing Cavity for the LHC High-Luminosity Upgrade	3568
	S.U. De Silva, J.R. Delayen, H. Park ODU, Norfolk, Virginia, USA Z. Li SLAC, Menlo Park, California, USA T.H. Nicol Fermilab, Batavia, Illinois, USA
	LHC High Luminosity Upgrade is in need of two crabbing systems that deflects the beam in both horizontal and vertical planes. The 400 MHz rf-dipole crabbing cavity system is capable of crabbing the proton beam in both planes. At present we are focusing our efforts on a complete crabbing system in the horizontal plane. Prior to LHC installation the crabbing system will be installed for beam test at SPS. The crabbing system consists of two rf-dipole cavities in the cryomodule. This paper discusses the electromagnetic design and mechanical properties of the rf-dipole crabbing system for SPS beam test.
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WEPWI037	Imperfection and Tolerance Analysis of HOM Couplers for ODU/SLAC 400 MHz Crabbing Cavity	3572
	S.U. De Silva, J.R. Delayen, H. Park ODU, Norfolk, Virginia, USA Z. Li SLAC, Menlo Park, California, USA R.G. Olave Old Dominion University, Norfolk, Virginia, USA
	In preparation for the LHC High Luminosity upgrade, a 400 MHz crab cavity has been developed jointly at ODU/SLAC, including two higher order mode couplers designed to dampen the wakefields in order to comply with the impedance budget specified for the LHC system. During fabrication, assembly, and processing of the couplers, a number of imperfections may arise that could modify the higher order mode spectrum and the associated impedance for each mode. We present here a detailed study of the imperfections of the horizontal- and vertical- HOM couplers, and the associated allowed tolerances for manufacture, assembly and processing.
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WEPWI038	Temperature Mapping of Nitrogen-doped Niobium Superconducting Radiofrequency Cavities	3575
	J. Makita ODU, Norfolk, Virginia, USA G. Ciovati, P. Dhakal JLab, Newport News, Virginia, USA
	It was recently shown that diffusing nitrogen on the inner surface of superconducting radiofrequency (SRF) cavities at high temperature can improve the quality factor of the niobium cavity. However, a reduction of the quench field is also typically found. To better understand the location of rf losses and quench, we used a thermometry system to map the temperature of the outer surface of ingot Nb cavities after nitrogen doping and electropolishing. Surface temperature of the cavities was recorded while increasing the rf power and also during the quenching. The results of thermal mapping showed no precursor heating on the cavities and quenching to be ignited near the equator where the surface magnetic field is maximum. Hot-spots at the equator area during multipacting were also detected by thermal mapping.
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WEPWI039	Engineering Study of Crab Cavity HOM Couplers for LHC High Luminosity Upgrade	3578
	H. Park, S.U. De Silva, J.R. Delayen, R.G. Olave ODU, Norfolk, Virginia, USA T. Capelli CERN, Geneva, Switzerland S.U. De Silva, J.R. Delayen, H. Park JLab, Newport News, Virginia, USA Z. Li SLAC, Menlo Park, California, USA T.H. Nicol Fermilab, Batavia, Illinois, USA N. Templeton STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	The LHC is planning to employ crab cavities for the high luminosity upgrade. Old Dominion University and SLAC National Laboratory are developing the crab cavity completed with the HOM damping couplers. The HOM couplers are coaxial type and perform over broad band up to 2 GHz. The amount of extracted power requires active cooling using liquid helium. The electromagnetic study has provided expected power dissipation on the coupler. Correlations between the fabrication tolerance and its damping performance have been studied and the results are providing guidelines on how to manufacture the HOM couplers. This paper summarizes the engineering studies; mechanical strength as a part of pressure system, thermal stability, and fabrication method to ensure the required tolerance.
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WEPWI040	Experiment and Results on Plasma Etching of SRF Cavities	3581
	J. Upadhyay, J.J. Peshl, S. Popović, L. Vušković ODU, Norfolk, Virginia, USA D.S. Im Old Dominion University, Norfolk, Virginia, USA H.L. Phillips, A-M. Valente-Feliciano JLab, Newport News, Virginia, USA
	The inner surfaces of SRF cavities are currently chemically treated (etched or electro polished) to achieve the state of the art RF performance. We designed an apparatus and developed a method for plasma etching of the inner surface for SRF cavities. The process parameters (pressure, power, gas concentration, diameter and shape of the inner electrode, temperature and positive dc bias at inner electrode) are optimized for cylindrical geometry. The etch rate non-uniformity has been overcome by simultaneous translation of the gas point-of-entry and the inner electrode during the processing. A single cell SRF cavity has been centrifugally barrel polished, chemically etched and RF tested to establish a baseline performance. This cavity is plasma etched and RF tested afterwards. The effect of plasma etching on the RF performance of this cavity will be presented and discussed.
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WEPWI042	A Table-Top Alpha-Magnet	3584
	A.V. Smirnov, R.B. Agustsson, T.J. Campese, Y.C. Chen, J.J. Hartzell, F.H. O'Shea, E. Spranza RadiaBeam, Santa Monica, California, USA
	Funding: Department of Energy, contract# DE- SC-FOA-0000760 A compact electromagnetic alpha-magnet design, engineering, and operation are presented. Initially the magnet has been designed for a low-energy, laser-free, coherent Cherenkov THz-sub-THz source. The source is designed and engineered in RadiaBeam in collaboration with ANL and integrated into the Injector Test Stand (ITS) of the Advanced Photon Source. The magnet having 15 cm depth, 14” height, and up to 4 T/m gradient features a rectangular yoke, two on-axis coils, and substantially truncated, partially non-hyperbolic poles. The tapered vacuum chamber for the magnet includes a motorized scraper and means of optical control. The novel and inexpensive design can be applied in relatively small, a few MeV facilities, where weight and dimensions are limited including free electron lasers, far infrared sources, inverse Compton sources of ultra-bright hard X-rays, as well as beam instrumentation for microbunching and phase-space manipulation (e.g., magnetic compression combined with round-to-flat beam transformation).
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WEPWI044	High-Power Magnetron Transmitter for the Electron Collider Ring of the MEIC Facility	3587
	G.M. Kazakevich Euclid TechLabs, LLC, Solon, Ohio, USA B.E. Chase, V.P. Yakovlev Fermilab, Batavia, Illinois, USA Y.S. Derbenev JLab, Newport News, Virginia, USA
	Operation of the 3-12 GeV electron collider 8-shape ring of the MEIC facility causes a Synchrotron Radiation (SR) of electrons in arcs with energy loss of ~20 kW/m at beam current of ~3 A. The total SR loss up to 2 MW per a revolution is presumed to compensate by Superconducting RF (SRF) accelerating cavities. To minimize the beam emittance, each individual SRF cavity is proposed to feed by an individual and independent RF source allowing a wide-band control in phase and power. Most efficient and less expensive in capital and maintenance costs the high-power transmitters based on magnetrons, injection-locked by phase-modulated signals, controlled in wide-band are proposed as the RF sources. The magnetron RF sources utilizing 2-cascade magnetrons allowing a wide-band phase and power control by the injection-locking phase-modulated signals were experimentally modelled by 2.45 GHz, CW, 1 kW magnetrons. Results of the modelling and adequacy of the transmitters for the SRF cavities are discussed in the presented article.
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WEPWI045	Status of Superconducting Traveling Wave Cavity for High Gradient Linac	3591
	R.A. Kostin, P.V. Avrakhov, A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio, USA T.N. Khabiboulline, Y.M. Pischalnikov, N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	The use of a travelling wave (TW) accelerating structure with a small phase advance per cell instead of standing wave may provide a significant increase of accelerating gradient in a superconducting linear accelerator. The TW section achieves an accelerating gradient 1.2-1.4 times larger than TESLA-shaped standing wave cavities for the same surface electric and magnetic fields. The final stage of a 3-cell superconducting travelling wave cavity development is presented. This cavity will be tested in travelling wave regime at cryogenic temperature.
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WEPWI046	Demonstration of Coaxial Coupling Scheme at 26 MV/m for 1.3 GHz TESLA-type SRF Cavities	3594
	Y. Xie, A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio, USA T.N. Khabiboulline, A. Lunin, V. Poloubotko, A.M. Rowe, N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA J. Rathke AES, Medford, New York, USA
	Funding: Work sponsored by DOE SBIR Grant DE-SC0002479. We will report the first successful rf test of a detachable coaxial coupler by Euclid Techlabs and Fermilab SRF development department. The coaxial coupling method has vast advantages compared with ordinary welded-on couplers. It totally eliminates coupler kicks and it is detachable and easy to clean. We reached 26 MV/m (no hard quench limit) with a quarter-wave detachable coaxial coupler. This is also a demonstration of the highest field gradient ever reached with a superconducting joint.
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WEPWI049	Commissioning of the 112 MHz SRF Gun and 500 MHz Bunching Cavities for the CeC PoP Linac	3597
	S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, V. Litvinenko, G. Narayan, P. Orfin, I. Pinayev, T. Rao, J. Skaritka, K.S. Smith, R. Than, J.E. Tuozzolo, E. Wang, Q. Wu, B. P. Xiao, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, I. Ben-Zvi, V. Litvinenko, T. Xin Stony Brook University, Stony Brook, USA P.A. McIntosh, A.J. Moss, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. The Coherent electron Cooling Proof-of-Principle (CeC PoP) experiment at BNL includes a short electron linac. During Phase I a 112 MHz superconducting RF photoemission gun and two 500 MHz normal conducting bunching cavities were installed and commissioned. The paper describes the Phase I linac layout and presents commissioning results for the cavities and associated RF, cryogenic and other sub-systems.
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WEPWI050	SRF and RF Systems for LEReC Linac	3600
	S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, A.V. Fedotov, G.T. McIntyre, S. Polizzo, K.S. Smith, R. Than, J.E. Tuozzolo, Q. Wu, B. P. Xiao, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, I. Ben-Zvi Stony Brook University, Stony Brook, USA V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. The Low Energy RHIC electron Cooling (LEReC) is under development at BNL to improve RHIC luminosity at low energies. It will consist of a short electron linac and two cooling sections, one for blue and one for yellow beams. For the first stage of the project, LEReC-1, we will to install a 704 MHz superconducting RF cavity and two normal conducting cavities operating at 704 MHz and 2.1 GHz. The SRF cavity will boost the electron beam energy up to 2 MeV. The warm cavities will be used to correct the energy spread introduced in the SRF cavity. The paper describes layouts of the SRF and RF systems, their parameters and status.
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WEPWI051	Update on the CeC POP 704 MHz 5-Cell Cavity Cryomodule Design and Fabrication	3603
	J.C. Brutus, S.A. Belomestnykh, I. Ben-Zvi, V. Litvinenko, I. Pinayev, J. Skaritka, L. Snydstrup, R. Than, J.E. Tuozzolo, W. Xu BNL, Upton, Long Island, New York, USA S.M. Gerbick, M.P. Kelly, T. Reid ANL, Argonne, USA T.L. Grimm, R. Jecks, J.A. Yancey Niowave, Inc., Lansing, Michigan, USA Y. Huang Fermilab, Batavia, Illinois, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. A 5-cell SRF cavity operating at 704 MHz will be used for the Coherent Electron Cooling Proof of Principle (CeC PoP) system currently under development for the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The CeC PoP experiment will demonstrate the ability of relativistic electrons to cool a single bunch of heavy ions in RHIC. The cavity will accelerate 2 MeV electrons from a 112 MHz SRF gun up to 22 MeV. Novel mechanical designs, including the helium vessel, vacuum vessel, tuner mechanism, and FPC are presented. This paper provides an overview of the design, the project status and schedule of the 704 MHz 5-cell SRF for the CeC PoP experiment. .
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WEPWI052	Commissioning and Early Operation Experience of the NSLS-II Storage Ring RF System	3606
	F. Gao, J. Cupolo, P. Davila, T. Dilgen, W.K. Gash, B. Holub, J.G. Kulpin, J. Papu, G. Ramirez, V. Ravindranath, B. Rose, J. Rose, R. Sikora, J. Tagger, M. Yeddulla BNL, Upton, Long Island, New York, USA
	The National Synchrotron Light Source II (NSLS-II) is a 3 GeV X-ray user facility commissioned in 2014. The storage ring RF system, essential for replenishing energy loss per turn of the electrons, consists of digital low level RF controllers, 310 kW CW klystron transmitters, CESR-B type superconducting cavities, as well as a supporting cryogenic system. Here we will report on RF commissioning and early operation experience of the system for beam current up to 200 mA.
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WEPWI053	HTS/lTS Hybrid High Field Superconducting Magnet Designs for the Proposed 100 TeV Proton Colliders	3609
	R.C. Gupta, M. Anerella, A.K. Ghosh, W. Sampson, J. Schmalzle BNL, Upton, Long Island, New York, USA J. Kolonko, D. Larson, R.M. Scanlan, R.J. Weggel, E. Willen Particle Beam Lasers, Inc., Northridge, California, USA C.M. Rey e2P, Knoxville, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under contract Number DE-SC0012704, with the U.S. Department of Energy and STTR contract DOE Grant Number DE-SC0011348. Proposed proton-proton colliders with a center-of-mass energy up to 100 TeV in a tunnel of desired size require the dipole magnets to be of very high field–20 teslas in some proposals. This field is beyond the limit of present conventional Low Temperature Superconductors (LTS) and requires using High Temperature Superconductors (HTS). The preliminary magnetic design presented in this paper is an HTS/LTS hybrid design with high strength HTS tape used in higher field regions and less expensive LTS in lower field regions, with a goal of optimizing the performance while reducing the cost. A major concern in the magnets built with the HTS tape is the large field errors associated with the conductor magnetization. The strategy presented here aims to reduce those errors considerably. This paper also presents a proof-of-principle design and program to experimentally evaluate that concept.
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WEPWI054	Design and Test of the RHIC CMD10 Abort Kicker	3612
	H. Hahn, M. Blaskiewiczpresenter, K.A. Drees, W. Fischer, W. Meng, J.-L. Mi, C. Montag, C. Pai, J. Sandberg, N. Tsoupas, J.E. Tuozzolo, W. Zhang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Planned and unplanned thyratron pre-fire triggered beam dumps have been observed in the yellow ring that were associated with quenches of the superconducting main ring magnets as the proton intensities increased in the FY1013 run. The increasing vacuum level indicated beam induced kicker ferrite heating causing lower magnetic kick field at a nominal pulse current. In anticipation of higher current and shorter bunches in FY2015 an accelerator improvement program was initiated to reduce the longitudinal coupling impedance with changes to the eddy-current strip geometry using Opera simulations and to change the CMD5005 to CMD10 ferrite. Results of the standard impedance measurements and of pulse current in heating tests to 170 °C are reported. All 10 dump kickers are being modified and are encapsulated with a cooling system for installation in the rings.
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WEPWI055	Commissioning and Early Operation for the NSLS-II Booster RF System	3615
	C. Marques, J. Cupolo, P. Davila, F. Gao, A. Goel, B. Holub, J.G. Kulpin, K. McDonald, J. Oliva, J. Papu, G. Ramirez, J. Rose, R. Sikora, C. Sorrentino, N.A. Towne BNL, Upton, Long Island, New York, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-SC0012704. The National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory (BNL) is a third generation 3GeV, 500mA synchrotron light source. We discuss the booster synchrotron RF system responsible for providing power to accelerate an electron beam from 200MeV to 3GeV. The RF system design and construction are complete and is currently in the operational phase of the NSLS-II project. Preliminary operational data is also discussed.
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WEPWI056	A Number of Upgrades on RHIC Power Supply System	3618
	C. Mi, D. Bruno, A. Di Lieto, J. Drozd, G. Heppner, T. Nolan, F. Orsatti, T. Samms, J. Sandberg, C. Schultheiss, R. Zapasek BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. This year marks the 15th run for the Relativistic Heavy Ion Collider (RHIC). Operation of a reliable superconducting magnet power supply system is a key factor of accelerator’s performance. Over the past 15 of years, the RHIC power supply system has been made many improvements to increase the machine availability and reduce failures. During these past 15 years of operating RHIC a lot of problems have been solved or addressed. In this paper some of the essential upgrades/improvements are discussed.
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WEPWI057	A New Bipolar qtrim Power Supply System	3621
	C. Mi, D. Bruno, A. Di Lieto, J. Drozd, G. Heppner, T. Nolan, F. Orsatti, T. Samms, J. Sandberg, C. Schultheiss, R. Zapasek BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. This year marks the 15th run of RHIC (Relativistic Heavy Ion Collider) operations. The reliability of superconducting magnet power supplies is one of the essential factors in the entire accelerator complex. Besides maintaining existing power supplies and their associated equipment, newly designed systems are also required based on the physicist’s latest requirements. A bipolar power supply was required for this year’s main quadrupole trim power supply. This paper will explain the design, prototype, testing, installation and operation of this recently installed power supply system.
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WEPWI058	The NSLS-II RF Cryogenic System	3624
	J. Rose, T. Dilgen, W.K. Gash, J. Gosman, J. Papu, R. Sikora BNL, Upton, Long Island, New York, USA Y. Jia Linde BOC Process Plants LLC, Tulsa, Oklahoma, USA C.M. Monroe Monroe Brothers Ltd., Moreton-in-Marsh, United Kingdom V. Ravindranath SLAC, Menlo Park, California, USA H. Wilhelm Linde Kryotechnik AG, Pfungen, Switzerland
	Funding: Work supported by DOE contract DE-SC0012704 The National Synchrotron Light Source II is a 3 GeV X-ray user facility commissioned in 2014. A new helium refrigerator system has been installed and commissioned to support the superconducting RF cavities in the storage ring. Special care was taken to provide very stable helium and LN2 pressures and flow rates to minimize microphonics and thermal effects at the cavities. Details of the system design along with commissioning and early operations data will be presented.
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WEPWI059	Higher Order Mode Filter Design for Double Quarter Wave Crab Cavity for the LHC High Luminosity Upgrade	3627
	B. P. Xiao, S.A. Belomestnykh, I. Ben-Zvi, J. Skaritka, S. Verdú-Andrés, Q. Wu BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, I. Ben-Zvi Stony Brook University, Stony Brook, USA G. Burt, B.D.S. Hall Cockcroft Institute, Lancaster University, Lancaster, United Kingdom G. Burt Lancaster University, Lancaster, United Kingdom R. Calaga, O. Capatina CERN, Geneva, Switzerland T.J. Jones STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: Work partly supported by US LARP, by US DOE under contract No. DE-AC02-05CH11231 and through BSA under contract No. DE-AC02-98CH10886. Research supported by EU FP7 HiLumi LHC - Grant Agreement 284404. A double quarter wave crab cavity (DQWCC) was designed for the Large Hadron Collider (LHC) luminosity upgrade. A compact Higher Order Mode (HOM) filter with wide stop band at the deflecting mode is developed for this cavity. Multi-physics finite element simulation results are presented. The integration of this design to the cavity cryomodule is described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI059
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WEPWI060	Cryogenic Test of Double Quarter Wave Crab Cavity for the LHC High Luminosity Upgrade	3630
	B. P. Xiao, S.A. Belomestnykh, I. Ben-Zvi, C. Cullen, L.R. Hammons, C. Marques, J. Skaritka, S. Verdú-Andrés, Q. Wu BNL, Upton, Long Island, New York, USA L. Alberty, R. Calaga, O. Capatina CERN, Geneva, Switzerland S.A. Belomestnykh, I. Ben-Zvi Stony Brook University, Stony Brook, USA Z. Li SLAC, Menlo Park, California, USA
	Funding: Work partly supported by US LARP, by US DOE under contract No. DE-AC02-05CH11231 and through BSA under contract No. DE-AC02-98CH10886. Research supported by EU FP7 HiLumi LHC - Grant Agreement 284404. A Proof-of-Principle (PoP) Double Quarter Wave Crab Cavity (DQWCC) was designed and fabricated for the Large Hadron Collider (LHC) luminosity upgrade. A vertical cryogenic test has been done at Brookhaven National Lab (BNL). The cavity achieved 4.5 MV deflecting voltage with a quality factor above 3×109. We report the test results of this design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI060
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WEPWI061	Design of Normal Conducting 704 MHz and 2.1 GHz Cavities for LEReC Linac	3634
	B. P. Xiao, S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, A.V. Fedotov, G.T. McIntyre, K.S. Smith, J.E. Tuozzolo, Q. Wu, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, I. Ben-Zvi Stony Brook University, Stony Brook, USA V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. To improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon, the Low Energey RHIC electron Cooler (LEReC) is currently under development at BNL. Two normal conducting cavities, a single cell 704 MHz cavity and a 3 cell 2.1 GHz third harmonic cavity, will be used in LEReC for bunch stretching and energy spread correction. In this paper we report the design of these two cavities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI061
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