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Wilson, K.

Paper Title Page
TPPT082 High Thermal Conductivity Cryogenic RF Feedthroughs for Higher Order Mode Couplers 4108
 
  • C.E. Reece, E. Daly, T. Elliott, J.P. Ozelis, H.L. Phillips, T.M. Rothgeb, K. Wilson, G. Wu
    Jefferson Lab, Newport News, Virginia
 
  Funding: This manuscript has been authorized by SURA, Inc. under Contract No. DE-AC05-84ER-40150 with the U.S. Department of Energy.

The use of higher-order-mode (HOM) pickup probes in the presence of significant fundamental rf fields can present a thermal challenge for cw or high average power SRF cavity applications. The electric field probes on the HOM-damping couplers on the JLab "High Gradient" and "Low Loss" seven-cell cavities for the CEBAF upgrade are exposed to approximately 10% of the peak magnetic field in the cavity. To avoid significant dissipative losses, these probes must remain superconducting during operation. Typical cryogenic rf feedthroughs provide a poor thermal conduction path for the probes, and provide inadequate stabilization. We have developed solutions that meet the requirements, providing a direct thermal path from the niobium probe, thorough single-crystal sapphire, to bulk copper which can be thermally stationed (or heat sunk). Designs, electromagnetic and thermal analyses, and performance data will be presented.

 
TPPT083 RF Conditioning and Testing of Fundamental Power Couplers for SNS Superconducting Cavity Production 4132
 
  • M. Stirbet, G.K. Davis, M. A. Drury, C. Grenoble, J. Henry, G. Myneni, T. Powers, K. Wilson, M. Wiseman
    Jefferson Lab, Newport News, Virginia
  • I.E. Campisi, Y.W. Kang, D. Stout
    ORNL, Oak Ridge, Tennessee
 
  Funding: This work was supported by U.S. DOE contract DE-AC0500R22725.

The Spallation Neutron Source (SNS) makes use of 33 medium beta (0.61) and 48 high beta (0.81) superconducting cavities. Each cavity is equipped with a fundamental power coupler, which should withstand the full klystron power of 550 kW in full reflection for the duration of an RF pulse of 1.3 msec at 60 Hz repetition rate. Before assembly to a superconducting cavity, the vacuum components of the coupler are submitted to acceptance procedures consisting of preliminary quality assessments, cleaning and clean room assembly, vacuum leak checks and baking under vacuum, followed by conditioning and RF high power testing. Similar acceptance procedures (except clean room assembly and baking) were applied for the airside components of the coupler. All 81 fundamental power couplers for SNS superconducting cavity production have been RF power tested at JLAB Newport News and, beginning in April 2004 at SNS Oak Ridge. This paper gives details of coupler processing and RF high power-assessed performances.

 
RPPE063 Concepts for the JLab Ampere-Class CW Cryomodule 3588
 
  • R.A. Rimmer, E. Daly, J. Henry, W.R. Hicks, J.P. Preble, M. Stirbet, H. Wang, K. Wilson, G. Wu
    Jefferson Lab, Newport News, Virginia
 
  Funding: This manuscript has been authored by SURA, Inc. under Contract No. DE-AC05-84ER-40150 with the U.S. Department of Energy, and by The Office of Naval Research under contract to the Dept. of Energy.

We describe the concepts and developments underway at JLab as part of the program to develop a new CW cryomodule capable of transporting ampere-level beam currents in a compact FEL. Requirements include real-estate gradient of at least 10 MV/m and very strong HOM damping to push BBU thresholds up by two or more orders of magnitude compared to existing designs. Cavity shape, HOM damping, power couplers, tuners etc. are being designed and optimized for this application. Cavity considerations include a large iris for beam halo, low-RF losses, HOM frequencies and Q’s, low peak surface fields, field flatness and microphonics. Module considerations include high packing factor, low static heat leak, image current heating of beam-line components, cost and maintainability. This module is being developed for the next generation ERL based high power FELs but may be useful for other applications such as electron cooling, electron-ion colliders, industrial processing etc.

 
RPPE061 SRF Accelerator Technology Transfer Experience from the Achievement of the SNS Cryomodule Production Run 3517
 
  • J. Hogan, T.C. Cannella, E. Daly, M. A. Drury, J.F. Fischer, T. Hiatt, P. Kneisel, J. Mammosser, J.P. Preble, T.E. Whitlatch, K. Wilson, M. Wiseman
    Jefferson Lab, Newport News, Virginia
 
  This paper will discuss the technology transfer aspect of superconducting RF expertise, as it pertains to cryomodule production, beginning with the original design requirements through testing and concluding with product delivery to the end user. The success of future industrialization, of accelerator systems, is dependent upon a focused effort on accelerator technology transfer. Over the past twenty years the Thomas Jefferson National Accelerator Facility (Jefferson Lab) has worked with industry to successfully design, manufacture, test and commission more superconducting RF cryomodules than any other entity in the United States. The most recent accomplishment of Jefferson Lab has been the successful production of twenty-four cryomodules designed for the Spallation Neutron Source (SNS). Jefferson Lab was chosen, by the United States Department of Energy, to provide the superconducting portion of the SNS linac due to its reputation as a primary resource for SRF expertise. The successful partnering with, and development of, industrial resources to support the fabrication of the superconducting RF cryomodules for SNS by Jefferson Lab will be the focus of this paper.