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Janssen, D.

Paper Title Page
TUPPH002 High Order Mode Analyses for the Rossendorf SRF Gun 228
 
  • D. Janssen
    FZD, Dresden
  • V. Volkov
    BINP SB RAS, Novosibirsk
 
  High Order Modes (HOM) excited by the beam in a superconducting RF gun (SRF gun) could destroy the quality of the electron beam. This problem is studied on the base of frequency domain description by considering of the equivalent RLC circuit contour for each HOM, periodical excited by a pulsed current source. Expression for the voltage, the field amplitude and the phase of the excited HOM has been obtained. The equations for the coupling impedances of monopole TM-HOM and TE-HOM in the RF gun cavity has been derived. In this calculation the change of the particle velocity due to acceleration is taken into account. Resonance frequencies, coupling impedances, unloaded and external quality factors, excitation voltages and field distributions for each HOM including trapped HOM are calculated for Rossendorf SRF gun up to the frequency of 7.5 GHz, using the complex field solver CLANS. The dependence of the calculated parameters from a cavity deformation has been studied. The influence of the seven most dangerous HOM on the beam quality has been estimated by particle tracking using the ASTRA code.  
WEPPH046 A Superconducting RF Photo-Injector for Operation at the ELBE Linear Accelerator 449
 
  • A. Arnold, H. Buettig, D. Janssen, M. Justus, U. Lehnert, P. Michel, K. Moeller, P. Murcek, Ch. Schneider, R. Schurig, F. Staufenbiel, R. Xiang, J. Teichert
    FZD, Dresden
  • T. Kamps
    BESSY GmbH, Berlin
  • G. Klemz, I. Will
    MBI, Berlin
  • W.-D. Lehmann
    IfE, Dresden
  • A. Matheisen, B. van der Horst
    DESY, Hamburg
  • J. Stephan
    IKST, Drsden
  • V. Volkov
    BINP SB RAS, Novosibirsk
  • P. vom Stein
    ACCEL, Bergisch Gladbach
 
  For the ELBE superconducting linear accelerator at Forschungszentrum Dresden-Rossendorf (FZD) a radiofrequency photoelectron injector with a superconducting cavity (SRF gun) is under development. The SRF gun combines the excellent beam quality which can be delivered by RF photoinjectors with the possibility of continuous wave operation. The superconducting niobium cavity of the injector consists of 3½ cells and contains a Cs2Te photocathode which is normal-conducting and cooled by liquid nitrogen. The RF frequency of the cavity is 1.3 GHz. The final electron energy will be about 9.5 MeV and the average electron current will be 1 mA. In the past years the SRF photo injector has been designed and fabricated. Several critical subsystems have been tested. For the cavity, the results of the RF measurements will be shown. An UV driver laser system has been developed which fulfils the different requirements (77 pC at 13 MHz, 1 nC at 500 kHz) for the future operation at ELBE. A photo cathode preparation system was developed and installed. The equipment is now in operation and the first series of Cs2Te photo cathodes have been produced.