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RF-structure

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TUP036 Large Grain Superconducting RF Cavities at DESY superconductivity, superconducting-RF, scattering, free-electron-laser 327
 
  • W. Singer, A. Brinkmann, J. Iversen, G. Kreps, A. Matheisen, D. Reschke, X. Singer
    DESY, Hamburg
  The DESY R&D program on cavities fabricated from large grain niobium explores the potential of this material for the production of approx. 1000 nine-cell cavities for the European XFEL. The program investigates both, the basic material properties comparing large grain material to standard sheet niobium and the material availability, fabrication and preparation aspects. Several single-cell cavities of TESLA shape have been fabricated from large grain niobium. A gradient up to 41 MV/m at Q0 = 1.4·1010 (TB = 2K) was measured after electropolishing. Recently the first large grain nine-cell cavities worldwide have been produced under contract of DESY with ACCEL Instruments Co. The first cavity is already tested with an accelerating gradient of 29 MV/m after BCP (Buffered Chemical Polishing) treatment.  
 
THP034 Effective Standing-Wave RF Structure for Charged-Particle Beam Deflector linac, coupling, simulation, impedance 649
 
  • V. V. Paramonov, L. V. Kravchuk
    RAS/INR, Moscow
  • S. A. Korepanov
    DESY Zeuthen, Zeuthen
  In this report we describe new standing wave pi-mode rf structure for charged particles deflection. For L-band frequency range parameters of the proposed structure are compared with classical TM110 mode deflecting cavity ones. With originating TE11n mode, our proposal has several times higher rf efficiency, one order wider pass-band and smaller (in times) transverse dimensions. The cavity design idea and typical are parameters are presented. Some particularities of the beam dynamics in the proposed structure are pointed out. Preferable field of structure application is discussed.  
 
THP078 High-Gradient Test of a Tungsten-Iris X-Band Accelerator Structure at NLCTA vacuum, linear-collider, collider, impedance 764
 
  • S. Doebert, A. Grudiev, S. T. Heikkinen, J. A. Rodriguez, I. Syratchev, M. Taborelli, W. Wuensch
    CERN, Geneva
  • C. Adolphsen, L. Laurent
    SLAC, Menlo Park, California
  The CLIC study group at CERN has built two X-band accelerating structures to be tested at SLAC in NLCTA. The structures consist of copper cells with insert irises made out of Molybdenum and Tungsten, clamped together and installed in a vacuum tank. These structures are exactly scaled versions from structures tested previously at 30 GHz and with short pulses (16 ns) in the CLIC Test Facility at CERN. At 30 GHz these structures reached gradients of 150 MV/m for Tungsten and 195 MV/m for Molybdenum. These experiments were designed to provide data on the dependence of rf breakdown on pulse length and frequency. This paper reports in particular on the high-gradient test of the tungsten-iris structure. At a pulse length of 16 ns a gradient of 125 MV/m was reached at X-band, 20 % lower than the 150 MV/m measured at 30 GHz in the CLIC Test Facility. The pulse length dependence and the dependence of the break down rate as a function of gradient were measured in detail. The results are compared to data obtained from the Molybdenum-Iris experiment at X-band which took place earlier as well as to 30 GHz data.  
 
THP089 Testbench of the HICAT RFQ at GSI rfq, ion, linac, proton 791
 
  • C. M. Kleffner, R. Baer, W. Barth, M. Galonska, F. Heymach, R. Hollinger, G. Hutter, W. Kaufmann, M. T. Maier, A. Reiter, B. Schlitt, M. Schwickert, P. S. Spaedtke, W. Vinzenz
    GSI, Darmstadt
  • A. Bechtold, A. Schempp
    IAP, Frankfurt-am-Main
  • R. Cee, E. Feldmeier, S. Vollmer
    HIT, Heidelberg
  In April 2006 the commissioning of the ion linac for the HICAT therapy facility in Heidelberg, Germany was started. In preparation of this commissioning process beam tests of the RFQ cavity with protons were carried out at GSI. The RFQ cavity for the HICAT facility was delivered to GSI in March 2005. The operation with an rf power up to 200 kW and a pulse width of 500 μsec could be accomplished successfully after a short time of rf-conditioning to assure the operation mode with carbon ions. A testbench for the RFQ cavity was constructed at GSI to allow for exact measurements of the output energy with the time of flight (ToF) method in addition to the beam tests at IAP Frankfurt. Due to the fact that the rebuncher is fully integrated into the RFQ rf-structure beam studies with different mechanical settings of the rebuncher had to be conducted. For each setting the effective voltage of the rebuncher could be estimated. The final mechanical setting was chosen with respect to required longitudinal matching to the IH structure behind of the RFQ.