• H. Bluem, D. Holmes, T. Schultheiss
  AES, Medford, NY
• I. Ben-Zvi, A. Burrill, J. Kewisch, D. Pate, T. Rao, R.J. Todd, E. Wang, Q. Wu
  BNL, Upton, Long Island, New York

Funding: AES is funded under DOE SBIR contract #DE-FG02-06ER84450. BNL work is performed under DOE contract #DE-AC02-98CH10886.

The use of an RF electron gun with a magnetized cathode in place of a DC gun for ILC may reduce the requirements for emittance damping rings. Maintaining adequate lifetime of the necessary cathode material requires vacuum levels in the 10^-11 torr range. While vacuum levels around the 10^-9 torr range are common in a normal conducting RF gun, the cryogenic pumping of the cavity walls of a superconducting RF (SRF) gun may maintain vacuum in the range needed for GaAs cathode longevity. Advanced Energy Systems, Inc. is collaborating with Brookhaven National Laboratory to investigate the generation of polarized electron beams using a SRF photocathode gun. The team is developing an experiment to study the quantum lifetime of a GaAs cathode in a SRF cavity and investigate long term cavity performance while integrated with a cesiated GaAs cathode*. In addition to the experimental investigation, a design is being developed that is compatible with the production of high aspect ratio polarized electron beams. The mechanical and physics aspects of this design will be discussed.

*J. Kewisch, et. al., Presentation at PAC09.

• J. Kewisch, I. Ben-Zvi, A. Burrill, D. Pate, T. Rao, R.J. Todd, E. Wang, Q. Wu
  BNL, Upton, Long Island, New York
• H. Bluem, D. Holmes, T. Schultheiss
  AES, Medford, NY

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.

Gallium arsenide cathodes are used in electron guns for the production of polarized electrons. In order to have a sufficient quantum efficiency lifetime of the cathode the vacuum in the gun must be 10^-11 torr or better, so that the cathode is not destroyed by ion back bombardment. All successful polarized guns are DC guns, because such vacuum levels can not be obtained in normal conducting RF guns. A superconductive RF gun may provide a sufficient vacuum level due to cryo-pumping of the cavity walls. We report on the progress of our experiment to test such a gun.

• A. Burrill, I. Ben-Zvi, R. Calaga, T. D'Ottavio, L.R. Dalesio, D.M. Gassner, H. Hahn, L.T. Hoff, A. Kayran, J. Kewisch, R.F. Lambiase, D.L. Lederle, V. Litvinenko, G.J. Mahler, G.T. McIntyre, B. Oerter, C. Pai, D. Pate, D. Phillips, E. Pozdeyev, C. Schultheiss, L. Smart, K. Smith, T.N. Tallerico, J.E. Tuozzolo, D. Weiss, A. Zaltsman
  BNL, Upton, Long Island, New York

This paper will present the preliminary results of the testing of the 703 MHz SRF cryomodule designed for use in the ampere class ERL under construction at Brookhaven National Laboratory. The preliminary VTA cavity testing, carried out at Jefferson Laboratory, demonstrated cavity performance of 20 MV/m with a Qo of 1x10¹⁰, results we expect to reproduce in the horizontal configuration. This test of the entire string assembly will allow us to evaluate all of the additional cryomodule components not previously tested in the VTA and will prepare us for our next milestone test which will be delivery of electrons from our injector through the cryomodule to the beam dump. This will also be the first demonstration of an accelerating cavity designed for use in an ampere class ERL, a key development which holds great promise for future machines.