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Sekutowicz, J.S.

Paper Title Page
TPPT056 Design of a Low Loss SRF Cavity for the ILC 3342
 
  • J.S. Sekutowicz
    DESY, Hamburg
  • L. Ge, K. Ko, L. Lee, Z. Li, C.-K. Ng, G.L. Schussman, L. Xiao
    SLAC, Menlo Park, California
  • I.G. Gonin, T.K. Khabiboulline, N. Solyak
    Fermilab, Batavia, Illinois
  • P. Kneisel
    Jefferson Lab, Newport News, Virginia
  • Y. Morozumi, K. Saito
    KEK, Ibaraki
 
  An international team comprising DESY, KEK, JLAB, FNAL and SLAC is collaborating on the design, fabrication and test of a low loss, 1.3 GHz 9-cell SRF structure as a potential improvement for the ILC main linac. The advantages of this structure over the TTF structure include lower cryogenic loss, shorter rise time, and less stored energy. Among the issues to be addressed in this design are HOM damping, Lorentz force detuning and multipacting. We will report on HOM damping calculations using the parallel finite element eigenmode solver Omega3P and the progress made towards an optimized design. Studies on multipacting and estimates of the Lorentz force detuning will also be presented.  
TPPT072 Effects of Electric and Magnetic Fields on the Performance of a Superconducting Cavity 3874
 
  • G. Ciovati, P. Kneisel
    Jefferson Lab, Newport News, Virginia
  • J.S. Sekutowicz, W. Singer
    DESY, Hamburg
 
  Funding: Work supported by the U.S. DOE Contract No DE-AC05-84ER40150.

A special two-cell cavity was designed to obtain surface field distributions suitable for investigation of electric and magnetic field effects on cavity performance. The cavity design and preliminary results were presented in a previous contribution. The bulk niobium cavity was heat-treated in a vacuum furnace at 1250C to improve the thermal conductivity. Three seamless hydroformed NbCu cavities of the same design were fabricated to investigate the role of the electron beam welds located in high field areas.

 
TPPT076 Preliminary Results from Single Crystal and Very Large Crystal Niobium Cavities 3991
 
  • P. Kneisel, G. Ciovati, G. Myneni
    Jefferson Lab, Newport News, Virginia
  • T. Carneiro
    Reference Metals, Bridgeville, Pennsylvania
  • J.S. Sekutowicz
    DESY, Hamburg
 
  Funding: Work supported by the U.S. DOE Contract No DE-AC05-84ER40150.

We have fabricated and tested several single cell cavities using material from very large grain niobium ingots. In one case the central grain exceeded 7" in diameter and this was used for a 2 GHz cavity. This activity had a dual purpose: to investigate the influence of grain boundaries on the often observed Q-drop at gradients Eacc > 20 MV/m in the absence of field emission, and to study the possibility of using ingot material for cavity fabrication without going through the expensive process of sheet fabrication. The sheets for these cavities were cut from the ingot by wire electro-discharge machining (EDM) and subsequently formed into half–cells by deep drawing. The following fabrication steps were standard: machining of weld recesses, electron beam welding of beam pipes onto the half cells and final equator weld to join both half cell/beam pipe subunits.The cavities showed heavy Q–disease caused by the EDM; after hydrogen degassing at 800C for 3 hrs in UHV the cavities showed promising results, however, a Q-drop above Eacc ~ 20 MV/m was still present. Testing of the cavities is still ongoing – so far accelerating gradients of 30 MV/m have been achieved.

 
TPPT077 Testing of HOM Coupler Designs on a Single Cell Niobium Cavity 4012
 
  • P. Kneisel, G. Ciovati, G. Myneni, G. Wu
    Jefferson Lab, Newport News, Virginia
  • J.S. Sekutowicz
    DESY, Hamburg
 
  Funding: Work supported by the U.S. DOE Contract No DE-AC05-84ER40150.

Coaxial higher order mode (HOM) couplers were developed initially for PETRA cavitiesand subsequently for TESLA cavities. They were adopted later for SNS and Jlab upgrade cavities. The principle of operation is the rejection of the fundamental mode by the tunable filter configuration of the coupler and the transmission of the HOMs. It has been recognized recently that, in high average power applications, the pick-up probe of the HOM coupler must be superconducting in order to avoid substantial heat dissipation by the fundamental mode fields and deterioration of the cavity Q. In addition, the thermal conduction of existing rf feedthrough designs is only marginally sufficient to keep even the niobium probe tip superconducting in cw operation. We have equipped a single-cell niobium cavity with different HOM coupler configurations and tested the different designs by measuring Q vs Eacc behavior at 2 K for different feedthroughs and probe tipmaterials

 
WPAP039 Progress on Lead Photocathodes for Superconducting Injectors 2598
 
  • J. Smedley, T. Rao
    BNL, Upton, Long Island, New York
  • P. Kneisel
    Jefferson Lab, Newport News, Virginia
  • J.L. Langner, P. Strzyzewski
    The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock
  • R.S. Lefferts, A.R. Lipski
    SBUNSL, Stony Brook, New York
  • J.S. Sekutowicz
    DESY, Hamburg
 
  Funding: This work was supported by DOE contracts DE-AC02-98CH10886, DE-AC03-76SF00515 and DE-FG02-97ER82336.

We present the results of our investigation of bulk, electroplated and vacuum deposited lead as suitable photocathode materials for superconducting RF injectors. The quantum efficiency of each sample is presented as a function of the wavelength of the incident light, from 310 nm to 190 nm. Quantum efficiencies of 0.3% have been obtained. Production of a niobium cavity with a lead-plated cathode is underway.

 
WPAP047 Preliminary Results from a Superconducting Photocathode Sample Cavity 2956
 
  • P. Kneisel
    Jefferson Lab, Newport News, Virginia
  • R.S. Lefferts, A.R. Lipski
    SBUNSL, Stony Brook, New York
  • J.S. Sekutowicz
    DESY, Hamburg
 
  Funding: Work supported by the U.S. DOE Contract No DE-AC05-84ER40150.

Pure niobium has been proposed as a photocathode material and recently a successful test has been conducted with a niobium single cell cavity to extract photo-currents from the surface of this cavity. However, the quantum efficiency of niobium is ~2·10-4, whereas electrodeposited lead has a ~15 times higher quantum efficiency. We have designed and tested a photo-injector niobium cavity, which can be used to insert photo-cathodes made of different materials in the high electric field region of the cavity. Experiments have been conducted with niobium and lead, which show that neither the Q- values of the cavity nor the obtainable surface fields are significantly lowered. This paper reports about the results from these tests.

 
TPAP043 Electron Cooling of RHIC 2741
 
  • I. Ben-Zvi, D.S. Barton, D.B. Beavis, M. Blaskiewicz, J.M. Brennan, A. Burrill, R. Calaga, P. Cameron, X.Y. Chang, R. Connolly, Yu.I. Eidelman, A.V. Fedotov, W. Fischer, D.M. Gassner, H. Hahn, M. Harrison, A. Hershcovitch, H.-C. Hseuh, A.K. Jain, P.D.J. Johnson, D. Kayran, J. Kewisch, R.F. Lambiase, V. Litvinenko, W.W. MacKay, G.J. Mahler, N. Malitsky, G.T. McIntyre, W. Meng, K.A.M. Mirabella, C. Montag, T.C.N. Nehring, T. Nicoletti, B. Oerter, G. Parzen, D. Pate, J. Rank, T. Rao, T. Roser, T. Russo, J. Scaduto, K. Smith, D. Trbojevic, G. Wang, J. Wei, N.W.W. Williams, K.-C. Wu, V. Yakimenko, A. Zaltsman, Y. Zhao
    BNL, Upton, Long Island, New York
  • D.T. Abell, D.L. Bruhwiler
    Tech-X, Boulder, Colorado
  • H. Bluem, A. Burger, M.D. Cole, A.J. Favale, D. Holmes, J. Rathke, T. Schultheiss, A.M.M. Todd
    AES, Princeton, New Jersey
  • A.V. Burov, S. Nagaitsev
    Fermilab, Batavia, Illinois
  • J.R. Delayen, Y.S. Derbenev, L. W. Funk, P. Kneisel, L. Merminga, H.L. Phillips, J.P. Preble
    Jefferson Lab, Newport News, Virginia
  • I. Koop, V.V. Parkhomchuk, Y.M. Shatunov, A.N. Skrinsky
    BINP SB RAS, Novosibirsk
  • I.N. Meshkov, A.O. Sidorin, A.V. Smirnov, G.V. Troubnikov
    JINR, Dubna, Moscow Region
  • J.S. Sekutowicz
    DESY, Hamburg
 
  We report progress on the R&D program for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This electron cooler is designed to cool 100 GeV/nucleon at storage energy using 54 MeV electrons. The electron source will be a superconducting RF photocathode gun. The accelerator will be a superconducting energy recovery linac. The frequency of the accelerator is set at 703.75 MHz. The maximum electron bunch frequency is 9.38 MHz, with bunch charge of 20 nC. The R&D program has the following components: The photoinjector and its photocathode, the superconducting linac cavity, start-to-end beam dynamics with magnetized electrons, electron cooling calculations including benchmarking experiments and development of a large superconducting solenoid. The photoinjector and linac cavity are being incorporated into an energy recovery linac aimed at demonstrating ampere class current at about 20 MeV. A Zeroth Order Design Report is in an advanced draft state, and can be found on the web at http://www.agsrhichome.bnl.gov/eCool/.

Under contract with the U.S. Department of Energy, Contract Number DE-AC02-98CH10886.

 
WPAP033 State-of-the-Art Electron Guns and Injector Designs for Energy Recovery Linacs (ERL) 2292
 
  • A.M.M. Todd, A. Ambrosio, H. Bluem, V. Christina, M.D. Cole, M. Falletta, D. Holmes, E. Peterson, J. Rathke, T. Schultheiss, R. Wong
    AES, Medford, NY
  • I. Ben-Zvi, A. Burrill, R. Calaga, P. Cameron, X.Y. Chang, H. Hahn, D. Kayran, J. Kewisch, V. Litvinenko, G.T. McIntyre, T. Nicoletti, J. Rank, T. Rao, J. Scaduto, K.-C. Wu, A. Zaltsman, Y. Zhao
    BNL, Upton, Long Island, New York
  • S.V. Benson, E. Daly, D. Douglas, H.F.D. Dylla, L. W. Funk, C. Hernandez-Garcia, J. Hogan, P. Kneisel, J. Mammosser, G. Neil, H.L. Phillips, J.P. Preble, R.A. Rimmer, C.H. Rode, T. Siggins, T. Whitlach, M. Wiseman
    Jefferson Lab, Newport News, Virginia
  • I.E. Campisi
    ORNL, Oak Ridge, Tennessee
  • P. Colestock, J.P. Kelley, S.S. Kurennoy, D.C. Nguyen, W. Reass, D. Rees, S.J. Russell, D.L. Schrage, R.L. Wood
    LANL, Los Alamos, New Mexico
  • D. Janssen
    FZR, Dresden
  • J.W. Lewellen
    ANL, Argonne, Illinois
  • J.S. Sekutowicz
    DESY, Hamburg
  • L.M. Young
    TechSource, Santa Fe, New Mexico
 
  Funding: This work is supported by NAVSEA, NSWC Crane, the Office of Naval Research, the DOD Joint Technology Office and by the U.S. DOE.

A key technology issue of ERL devices for high-power free-electron laser (FEL) and 4th generation light sources is the demonstration of reliable, high-brightness, high-power injector operation. Ongoing programs that target up to 1 Ampere injector performance at emittance values consistent with the requirements of these applications are described. We consider that there are three possible approaches that could deliver the required performance. The first is a DC photocathode gun and superconducting RF (SRF) booster cryomodule. Such a 750 MHz device is being integrated and will be tested up to 100 mA at the Thomas Jefferson National Accelerator Facility beginning in 2007. The second approach is a high-current normal-conducting RF photoinjector. A 700 MHz gun will undergo thermal test in 2006 at the Los Alamos National Laboratory, which, if successful, when equipped with a suitable cathode, would be capable of 1 Ampere operation. The last option is an SRF gun. A half-cell 703 MHz SRF gun capable of delivering 1.0 Ampere will be tested to 0.5 Ampere at the Brookhaven National Laboratory in 2006. The fabrication status, schedule and projected performance for each of these state-of-the-art injector programs will be presented.

 
RPPE067 Design and Fabrication of an FEL Injector Cryomodule 3724
 
  • J. Rathke, A. Ambrosio, H. Bluem, M.D. Cole, E. Peterson, T. Schultheiss, A.M.M. Todd
    AES, Princeton, New Jersey
  • I.E. Campisi, E. Daly, J. Hogan, J. Mammosser, G. Neil, J.P. Preble, R.A. Rimmer, C.H. Rode, T.E. Whitlatch, M. Wiseman
    Jefferson Lab, Newport News, Virginia
  • J.S. Sekutowicz
    DESY, Hamburg
 
  Funding: This work is supported by NAVSEA, MDA, and SMDC.

Advanced Energy Systems has recently completed the design of a four cavity cryomodule for use as an FEL injector accelerator on the JLAB Injector Test Stand. Fabrication is nearing completion. Four 748.5 MHz single cell superconducting cavities have been completed and are currently at Jefferson Lab for final processing and test prior to integration in the module. This paper will review the design and fabrication of the cavities and cryomodule.