• Z.A. Conway, D.L. Hartill, H. Padamsee, E.N. Smith
  CLASSE, Ithaca, New York

Funding: Work Supported by the NSF and DOE

Superconducting RF cavity quench detection is presently a cumbersome procedure requiring two or more expensive cold tests. One cold test identifies the cell-pair involved via quench field measurements in several 1.3 GHz TM010 pass-band modes. A second test follows with numerous fixed thermometers attached to the culprit cell-pair to identify the particular cell. A third measurement with many localized thermometers is necessary to zoom in on the quench spot. We report here on a far more efficient alternative method which utilizes a few (e.g. 8) oscillating superleak transducers (OST) to detect the He-II second sound wave driven by the defect induced quench. Results characterizing defect location with He-II second sound wave OST detection, powering multiple modes of the 1.3GHz TM010 passband to locate multiple defects, and corroborating measurements with carbon thermometers will be presented.

• Z.A. Conway, E.P. Chojnacki, D.L. Hartill, M. Liepe, D. Meidlinger, H. Padamsee, J. Sears, E.N. Smith
  CLASSE, Ithaca, New York

Funding: Work Supported by the NSF and the DOE

An innovative reentrant cavity design instigated the initial, highly successful, superconducting niobium reentrant-single-cell cavity tests at Cornell and KEK. Prompted by the success of the single cell program a joint effort of Cornell University and Advanced Energy Systems (AES) fabricated two multiple-cell reentrant cavities: a three-cell and a nine-cell cavity. This paper reports the development status of these two cavities. First, the results of cold tests, superfluid helium defect location and repair work on the reentrant nine-cell cavity will be presented. Second, the results of cold tests, including defect location and repair efforts of the reentrant three-cell cavity will be presented.

• E.P. Chojnacki, S.A. Belomestnykh, S.S. Chapman, R.D. Ehrlich, G.H. Hoffstaetter, M. Liepe, H. Padamsee, J. Sears, E.N. Smith, V. Veshcherevich
  CLASSE, Ithaca, New York

Funding: Work supported by NSF, New York State, and Cornell University

A cryomodule design for the Cornell Energy Recovery Linac (ERL) will be based on TTF technology, but must have several unique features dictated by the ERL beam parameters. The main deviations from TTF are that the HOM loads must be on the beamline for sufficient damping, that the average power through the RF couplers is low, and that cw beam operation introduces higher heat loads. Several of these challenges were addressed for the Cornell ERL Injector, from which fabrication and operational insight was gained. A baseline design for the Cornell ERL Linac cryomodule will be presented that includes fabrication and operational considerations along with thermal and mechanical analyses.

• I.V. Bazarov, S.A. Belomestnykh, E.P. Chojnacki, J. Dobbins, B.M. Dunham, R.D. Ehrlich, M.J. Forster, C.M. Gulliford, G.H. Hoffstaetter, Y. Li, M. Liepe, X. Liu, F. Löhl, D.G. Ouzounov, H. Padamsee, D.H. Rice, V.D. Shemelin, E.N. Smith, K.W. Smolenski, M. Tigner, V. Veshcherevich
  CLASSE, Ithaca, New York
• H. Li
  Cornell University, Ithaca, New York
• H. K. Sayed
  JLAB, Newport News, Virginia

Cornell University has built a high average current electron injector for use with an Energy Recovery Linac. The injector is capable of up to 100 mA average current at 5 MeV (33 mA at 15 MeV) and is expected to produce the ultra low emittances needed for an ERL. This talk will give an overview of the initial performance of this injector and summarize a spectrum of beam physics experiments undertaken to demonstrate low emittance, high average current operation.

Slides

• Y. Li, M.G. Billing, S. Greenwald, T.I. O'Connell, M.A. Palmer, J.P. Sikora, E.N. Smith, K.W. Smolenski
  CLASSE, Ithaca, New York
• J.N. Corlett, R. Kraft, D.V. Munson, D.W. Plate, A.W. Rawlins
  LBNL, Berkeley, California
• K. Kanazawa, Y. Suetsugu
  KEK, Ibaraki
• M.T.F. Pivi
  SLAC, Menlo Park, California

Funding: Work supported by the National Science Foundation, the US Department of Energy, and the Japan/US Cooperation Program

Wiggler magnets are one of the key components in the ILC Damping Ring. It is critical to the ILCDR GDE to understand electron cloud (EC) growth and patterns, and to develop EC suppression techniques in the wiggler beampipes. The CESR-c superconducting wigglers, closely matching the parameters of the ILCDR wigglers, serve as unique testing vehicles. As part of the CesrTA project, we replaced the copper beampipes of two SCWs with EC diagnostic beampipes, where one of the beampipes is uncoated and the second is coated with a thin TiN film. Each of the EC diagnostic beampipes is equipped with three retarding field analyzers (RFAs) at strategic longitudinal locations in the wiggler field. Each of the RFAs has 12-fold segmentation to measure the horizontal EC density distribution. To maintain sufficient vertical beam aperture and to fit within the SCW warm bore, a thin style of RFA (with a thickness of 2.5 mm) has been developed and deployed. These SCWs with RFA-equipped beampipe have been installed and successfully operated in the re-configured CesrTA vacuum system. This paper describes the design and the construction of the RFA-equipped SCW beampipes and operational experience.

• M.A. Palmer, J.P. Alexander, M.G. Billing, J.R. Calvey, S.S. Chapman, G.W. Codner, C.J. Conolly, J.A. Crittenden, J. Dobbins, G. Dugan, E. Fontes, M.J. Forster, R.E. Gallagher, S.W. Gray, S. Greenwald, D.L. Hartill, W.H. Hopkins, J. Kandaswamy, D.L. Kreinick, Y. Li, X. Liu, J.A. Livezey, A. Lyndaker, V. Medjidzade, R.E. Meller, S.B. Peck, D.P. Peterson, M.C. Rendina, P. Revesz, D.H. Rice, N.T. Rider, D. L. Rubin, D. Sagan, J.J. Savino, R.D. Seeley, J.W. Sexton, J.P. Shanks, J.P. Sikora, K.W. Smolenski, C.R. Strohman, A.B. Temnykh, M. Tigner, S. Vishniakou, W.S. Whitney, T. Wilksen, H.A. Williams
  CLASSE, Ithaca, New York
• J.M. Byrd, C.M. Celata, J.N. Corlett, S. De Santis, M.A. Furman, A. Jackson, R. Kraft, D.V. Munson, G. Penn, D.W. Plate, A.W. Rawlins, M. Venturini, M.S. Zisman
  LBNL, Berkeley, California
• J.W. Flanagan, P. Jain, K. Kanazawa, K. Ohmi, H. Sakai, K. Shibata, Y. Suetsugu
  KEK, Ibaraki
• K.C. Harkay
  ANL, Argonne
• Y. He, M.C. Ross, C.-Y. Tan, R.M. Zwaska
  Fermilab, Batavia
• R. Holtzapple
  CalPoly, San Luis Obispo, CA
• J.K. Jones
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• D. Kharakh, M.T.F. Pivi, L. Wang
  SLAC, Menlo Park, California
• E.N. Smith
  Cornell University, Ithaca, New York
• A. Wolski
  Cockcroft Institute, Warrington, Cheshire

Funding: Support provided by the US National Science Foundation, the US Department of Energy, and the Japan/US Cooperation Program.

In March of 2008, the Cornell Electron Storage Ring (CESR) concluded twenty eight years of colliding beam operations for the CLEO high energy physics experiment. We have reconfigured CESR as an ultra low emittance damping ring for use as a test accelerator (CesrTA) for International Linear Collider (ILC) damping ring R&D. The primary goals of the CesrTA program are to achieve a beam emittance approaching that of the ILC Damping Rings with a positron beam, to investigate the interaction of the electron cloud with both low emittance positron and electron beams, to explore methods to suppress the electron cloud, and to develop suitable advanced instrumentation required for these experimental studies (in particular a fast x-ray beam size monitor capable of single pass measurements of individual bunches). We report on progress with the CESR conversion activities, the status and schedule for the experimental program, and the first experimental results that have been obtained.

Slides