• M. Liepe, S.A. Belomestnykh, R.L. Geng, V. Medjidzade, H. Padamsee, V.D. Shemelin, V. Veshcherevich
  Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York

The Cornell ERL Prototype injector will accelerate bunches from an electron source to an energy of several MeV, while preserving the ultra-low emittance of the beam. The injector linac will be based on superconducting RF technology with five 2-cell RF cavities operated in cw mode. The beam tubes on one side of the cavities have been enlarged to propagate Higher-Order-Mode power from the cavities to broadband RF ring-absorbers located at 80 K between the cavities. The axial symmetry of these ferrite based absorbers, together with two symmetrically placed input couplers per cavity, avoids transverse on-axis fields, which would cause emittance growth. Each cavity is surrounded by a LHe vessel and equipped with a frequency tuner. The cryomodule provides the support and alignment for the cavity string, the LN cooling of the ferrite loads, and the 2K LHe cryogenic system for the high cw heat load of the cavities. In this paper we give an overview of the ERL injector cryomodule design.

• S.A. Belomestnykh, R.P.K. Kaplan, J.J.R. Reilly, V. Veshcherevich
  Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York

An instability of the active RF cavity field control loop was observed during experiments with beam-driven (passive) superconducting cavities in CESR when the cavity external Q factor was raised to a value above 1x10⁷. A computer model was developed and further experiments have been performed to study this instability and find a way to cure it. The results of simulations are presented alongside the experimental results.

• S.A. Belomestnykh, R.P.K. Kaplan, H. Padamsee, P. Quigley, J.J.R. Reilly, J. Sears, V. Veshcherevich
  Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
• S. Bauer, M. Pekeler, H. Vogel
  ACCEL, Bergisch Gladbach
• L.-H. Chang, C.-T. Chen, F.-Z. Hsiao, M.-C. Lin, G.-H. Luo, C. Wang, T.-T. Yang, M.-S. Yeh
  NSRRC, Hsinchu
• E. Matias, J. Stampe, M.S. de Jong
  CLS, Saskatoon, Saskatchewan

Upon signing a technology transfer agreement with Cornell University, ACCEL began producing turn-key 500 MHz superconducting cavity systems. Four such cryomodules have been delivered, commissioned and installed in accelerators for operation to date. Two more cryomodules are scheduled for testing in early 2005. One of them will be put in operation at Canadian Light Source (CLS); the other will serve as a spare at Taiwan Light Source (TLS). The commissioning results and operational experience with the cryomodules in CESR, CLS and TLS are presented.