Author: Ben-Zvi, I.
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MOPBTH005
 A FFAG-ERL at Cornell, a BNL/Cornell Collaboration  
 
  • G.H. Hoffstaetter, I.V. Bazarov, J. Dobbins, B.M. Dunham, C.E. Mayes, J.R. Patterson, D. Sagan
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • I. Ben-Zvi, J.S. Berg, M. Blaskiewicz, S.J. Brooks, K.A. Brown, W. Fischer, Y. Hao, W. Meng, F. Méot, M.G. Minty, S. Peggs, V. Ptitsyn, T. Roser, P. Thieberger, D. Trbojevic, N. Tsoupas
    BNL, Upton, Long Island, New York, USA
  
  Cornell University has prototyped technology essential for any high-brightness electron ERL. This includes a DC gun and an SRF injector Linac, a high-current CW cryomodule, a high-power beam stop, and several diagnostics tools for high-current and high-brightness beams. All these are now available to equip a one-cryomodule ERL, and laboratory space has been cleared out and is radiation shielded to install this ERL at Cornell. BNL has designed a multi-turn ERL for eRHIC where beam is transported 22 times around the RHIC tunnel. The number of transport lines is minimized by using two non-scaling FFAG arcs. A collaboration between BNL and Cornell has been formed to investigate the new NS-FFAG optics of this design, built with permanent magnets, and to commission the unprecedented multi-turn ERL operation. This collaboration plans to install a NS-FFAG return loop and the associated optics-matching sections at Cornell’s one-cryomodule ERL. This FFAG-ERL will be installed in several stages, each of which investigates crutial parts of this new design.  
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MOPDTH014 Status and Commissioning Results of the R&D ERL at BNL 10
 
  • D. Kayran, Z. Altinbas, D.R. Beavis, S.A. Belomestnykh, I. Ben-Zvi, S. Deonarine, D.M. Gassner, R.C. Gupta, H. Hahn, L.R. Hammons, C. Ho, J.P. Jamilkowski, P. K. Kankiya, N. Laloudakis, R.F. Lambiase, V. Litvinenko, G.J. Mahler, L. Masi, G.T. McIntyre, T.A. Miller, J. Morris, D. Phillips, V. Ptitsyn, T. Rao, T. Seda, B. Sheehy, L. Smart, K.S. Smith, T. Srinivasan-Rao, A.N. Steszyn, R. Than, E. Wang, D. Weiss, H. Xie, W. Xu, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh, I. Ben-Zvi, L.R. Hammons, D. Kayran, V. Litvinenko, V. Ptitsyn
    Stony Brook University, Stony Brook, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
An ampere class 20 MeV superconducting Energy Recovery Linac (ERL) is presently under commissioning at Brookhaven National Laboratory (BNL) for testing of concepts relevant for high-energy coherent electron cooling and electron-ion colliders. The injector subsystems tests and installation were finished in fall 2013. The injector includes: SRF photoelectron gun with 1 MW amplifier, 10W green drive-laser system, multi-alkaline cathode deposition system, cathode transport system, beam instrumentation and control. * The first photo current from ERL SRF gun has been observed in fall 2014 after second attempt. Completion of the ERL returning loop components installation is scheduled for April 2015 following full power ERL commissioning. After ERL commissioning in BLDG912 the ERL will be relocated to RHIC IP2 to be used as low energy RHIC electron cooler.
* D.Kayran et al., First test results from SRF photoinjector for the R&D ERL at BNL, IPAC'14, pp. 748-750 		 
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TUIBLH1023
 The Progress of Funneling Gun for eRHIC Injector  
 
  • E. Wang, I. Ben-Zvi, D.M. Gassner, R.F. Lambiase, W. Meng, T. Rao, B. Sheehy, J. Skaritka
    BNL, Upton, Long Island, New York, USA
  • M.A. Ackeret, J.R. Pietz
    Transfer Engineering and Manufacturing, Inc, Fremont, California, USA
  • E. Dobrin, R.C. Miller, K.A. Thompson, C. Yeckel
    Stangenes Industries, Palo Alto, California, USA
  • O.H. Rahman
    Stony Brook University, Stony Brook, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A prototype of the high average current polarized electron funneling gun as ERL-FFAG based eRHIC injector has built at BNL. In last year, we generated two beams from GaAs photocathodes by CW green laser and combined by a switched combiner field. We observed the combined beams on a YAG crystal ,measured the photocurrent and cathode lifetime by a Faraday cup. In this paper, we will describe the major components of the gun and beam line optics. We will also discuss the recent beam test results and high voltage conditioning results. 		 
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TUICLH1027
 Characterization of Multi-alkali Antimonide Cathode at Cryogenic Temperatures and its Performance in SRF Gun  
 
  • H.M. Xie
    PKU, Beijing, People's Republic of China
  • S.A. Belomestnykh, I. Ben-Zvi, D. Kayran, G.T. McIntyre, B. Sheehy, R. Than, E. Wang, D. Weiss, W. Xu
    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.
An alkali antimonide photocathode was tested in BNL 704 MHz SRF gun. The cathode QE and lifetime were measured inside the gun. We also observed a reduction on the QE upon cooling down to cryogenic temperature. In this paper, we propose an analytical model and present a Monte-Carlo simulation code to explain this QE decrease. Both results compared with experiments. Effect of cooling the cathode to cryogenic temperature and Schottky effect on QE will be discussed. 		 
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TUIDLH1036
 Commissioning Program for the 704 MHz SRF Gun at BNL  
 
  • W. Xu, S.A. Belomestnykh, I. Ben-Zvi, D. Kayran
    BNL, Upton, Long Island, New York, USA
  
  A 704 MHz superconducting RF photoemission electron gun for the R&D ERL project is under commissioning at BNL. It successfully generated the first photoemission beam in November 2014. The BNL SRF gun cavity operates well in CW mode up to 2 MV. However, its performance with inserted cathode stalk suffered due to multipacting in the quarter-wavelength choke-joint. A new multipacting-free cathode stalk was designed and tested. The test results proved that it is a truly “multipacting-free” stalk. With the new cathode, the gun is able to operate in CW mode. The total conditioning time of the new cathode stalk is very short. This paper describes configuration of the SRF gun test and the sub-systems. RF and thermal design of new cathode stalk and its conditioning results are presented. Finally, we report the latest results of the SRF gun commissioning, including the cavity performance, cathode QE measurements, beam current/energy measurements.  
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WEICLH2061
 SRF Cavities for High Current ERLs  
 
  • W. Xu, S.A. Belomestnykh, I. Ben-Zvi, H. Hahn
    BNL, Upton, Long Island, New York, USA
  
  The electron-ion collider eRHIC, proposed at BNL, requires superconducting RF cavities, which are able to support high average current beams. Two types of ERL lattices were designed for eRHIC. The first one is a conventional lattice, and the other one is a non-scaling FFAG lattice, which was proposed recently. For the conventional lattice with up to eight ERL passes, a 704 MHz 5-cell BNL3 cavity was designed, fabricated and tested vertically at BNL. The FFAG-based eRHIC design requires a high-current low-frequency SRF energy recovery linac with up to 16 passes. A 422 MHz 5-cell cavity (BNL4) was designed for for this lattice. This paper addresses development of the SRF cavities for eRHIC, including the cavity design, fabrication and test results. Beam-break-up (BBU) analysis for these cavities is presented as well. An HOM damping scheme for achiving low higher-order-modes’ impedance is proposed. HOM couplers were designed for these high current SRF cavities. HOM coupler prototypes were fabricated and tested.  
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