A   B   C   D   E   F   G   H   I   K   L   M   N   O   P   Q   R   S   T   U   V   W  

higher-order-mode

Paper Title Other Keywords Page
MOP067 First High Power Tests of CLIC Prototype Accelerating Structures with HOM Waveguide Damping damping, linac, target, HOM 208
 
  • S. Döbert, A. Grudiev, G. Riddone, W. Wuensch, R. Zennaro
    CERN, Geneva
  • C. Adolphsen, F. Wang, J.W. Wang
    SLAC, Menlo Park, California
  • T. Higo, S. Matsumoto, K. Yokoyama
    KEK, Ibaraki
 
 

Prototype accelerating structures for the Compact Linear Collider (CLIC) are being developed and high-power tested in a collaboration between SLAC, KEK and CERN. Several undamped, low group-velocity and strongly tapered prototypes (of the so-called T18 design) have been operated above 100 MV/m average gradient at a very low breakdown rates. Recently two new structures with the same iris apertures but now including higher order mode damping waveguides in each cell (TD18 design) have been tested at SLAC and KEK. The damped versions could be processed to similar gradients but an increased breakdown rate was observed. The damping waveguides lead to a magnetic field enhancement in the outer diameter of the cells which results in increased pulsed surface heating. The maximum pulsed temperature rise is 80 deg at the design gradient of 100 MV/m compared to only 20 deg for the undamped version. The high-power tests of the two TD18 structures are analyzed with special emphasis on the influence on breakdown rate of the enhanced magnetic field and consequent increased pulsed surface temperature rise.

 
THP015 A Review of the 1.3GHz Superconducting 9-Cell Cavity Fabrication for DESY cavity, HOM, linac, electron 794
 
  • J. Iversen, R. Bandelmann, G. Kreps, W.-D. Möller, D. Proch, J.K. Sekutowicz, W. Singer
    DESY, Hamburg
 
 

Since 1993 DESY ordered 165 1.3GHz 9-cell superconducting cavities. The cavities have been developed for TeV-Energy Superconducting Linear Accelerator (TESLA) and are used in the linac of the Free Electron Laser in Hamburg (FLASH). The fabrication of all cavities was done in 9 production groups at industry. From the beginning the industrialization was carried out in close collaboration between DESY and the industry. From order to order the cavity design was optimized and the fabrication sequences were improved to realize stable and better cavity performance and to safe costs. Now a final cavity design for the European XFEL is defined. We summarize the development phases and design changes up to the final XFEL design. An outlook on the near future production of hundreds of cavities for XFEL based on our experience will be given.

 
THP024 Design Sensitivities of the Superconducting Parallel-Bar Cavity cavity, luminosity, HOM, superconductivity 812
 
  • S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia
 
 

The superconducting parallel-bar cavity has properties that makes it attractive as a deflecting or crabbing rf structure. For example it is under consideration as an rf separator for the Jefferson Lab 12 GeV upgrade and as a crabbing structure for a possible LHC luminosity upgrade. In order to maintain the purity of the deflecting mode and avoid mixing with the near accelerating mode caused by geometrical imperfection, a minimum frequency separation is needed which depends on the expected deviations from perfect symmetry. We have done an extensive analysis of the impact of several geometrical imperfections on the properties of the parallel-bar cavities and the effects on the beam, and present the results in this paper.

 
THP034 Baseline Cavity Design for Cornell's Energy Recovery Linac cavity, HOM, linac, dipole 830
 
  • N.R.A. Valles, M. Liepe
    CLASSE, Ithaca, New York
 
 

This paper discusses the baseline superconducting RF cavity design to be used in Cornell's Energy Recovery Linac, a next generation light source. We discuss the methods used to obtain the design and present the cavity's figures of merit. The baseline cavity design is ready for prototyping, which will begin in the fall of 2010. Finally, we introduce small variations in the center cell design to increase the threshold current through the cavity by increasing the higher order mode relative frequency spread in the main linac, that have the effect of more than doubling the threshold current to 450 mA.