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| THPPH008 |
High Peak Current Design of a Superconducting Cavity for a SRF Photoinjector
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571 |
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- D. Janssen
FZR, Dresden
- F. Marhauser
BESSY GmbH, Berlin
- V. Volkov
BINP SB RAS, Novosibirsk
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In collaboration between BESSY, DESY, FZR, MBI and BINP a SRF electron gun is under development. The progress obtained in the last year is reported on this conference. The motivation for the design of a new gun cavity is the FEL project at BESSY. The electron injector of the linac should produce bunches with a charge of 2.5 nC and a transverse emittance of 1.5 mm mrad. In order to compensate the emittance expansion by space charge effects a large electric field on the cavity axis and a strong magnetic field near the cathode are necessary. The strengths of these fields are limited by the maximum magnetic surface field in superconducting cavities. We have designed a 1.5 cell gun cavity, where the magnetic field is realized by an additional RF mode (TE mode). In order to reduce third order effects of the RF fields, for the accelerating field a frequency below the linac frequency is used. The laser pulse, which creates the electron bunch, has a length of 20ps and a rise time of 2ps. In the tracking calculation the electrons start with an average energy of 1eV. For a bunch charge of 2.5 nC a transverse emittance of 1.8 mm mrad has been obtained. The maximal surface field is 160 mT.
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| THPPH007 |
First RF-Measurements at the 3.5-Cell SRF-Photo-Gun Cavity in Rossendorf
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567 |
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- A. Arnold, H. Buettig, D. Janssen, U. Lehnert, P. Michel, K. Moeller, P. Murcek, Ch. Schneider, R. Schurig, F. Staufenbiel, J. Teichert, R. Xiang
FZR, Dresden
- T. Kamps, D. Lipka, F. Marhauser
BESSY GmbH, Berlin
- G. Klemz
DESY Zeuthen, Zeuthen
- W.-D. Lehmann
IfE, Dresden
- A. Matheisen, B. van der Horst
DESY, Hamburg
- J. Stephan
IKST, Drsden
- V. Volkov
BINP SB RAS, Novosibirsk
- I. Will
MBI, Berlin
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At the Forschungszentrum Rossendorf the development and the setup of the 2nd superconducting radio frequency photo electron injector (SRF-Photo-Gun) is nearly finished. One of the main attention was focussed at the treatment of the cavity. Their RF properties were measured at room temperature. The warm tuning was carried out considering pre-stressing and tuning range of both tuners (half cell and full cells). The adjusted field profiles and pass band frequencies of the four fundamental modes met the requirements. An external Q study of the main coupler yielded to an optimal antenna length and showed very good agreement between simulation and measurement. Furthermore the characteristics of the choke filter and both HOM filters were simulated, measured and tuned at the pi-mode frequency. The preparation (etching and rinsing) and the cold test were successfully done at DESY. The poster presents the setup for the measurements as well as a comparison of the simulated and measured results. Submitted as poster to the 2006 FEL conference
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