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Title |
Page |
| MOPCH151 |
Pulsed RF System for the ELBE Superconducting Accelerator
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411 |
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- A. Buechner, F.G. Gabriel
FZR/FWFE, Dresden
- H. Buettig, U. Lehnert, P. Michel, Ch. Schneider, R. Schurig
FZR, Dresden
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The RF system for the ELBE accelerator was originally designed for CW mode. Although this works problem-free tests have shown that it is possible to reach higher gradients in the TESLA cavities with a pulsed RF system. The new RF system will be presented together with measurements of the achievable gradients. Roughly 30% higher gradients could now be used in pulsed mode. As positive side effects the radiation by field emission is reduced by the duty cycle and an easy in situ RF conditioning of cavities and coupler windows is possible.
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| MOPCH152 |
A Pulsed-RF High-power Processing Effect of Superconducting Niobium Cavities observed at the ELBE Linear Accelerator
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413 |
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- U. Lehnert, H. Buettig, P. Michel, Ch. Schneider, R. Schurig
FZR, Dresden
- A. Buechner, F.G. Gabriel
FZR/FWFE, Dresden
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The driver LINAC of the ELBE radiation source is built for cw operation. However, in some cases a pulsed-mode operation was desired to extend the otherwise stringent gradient limits. The main restriction results from field emission that decreases the Q of the cavities which was evaluated from measurements of the liquid helium consumption. After pulsed-mode operation with gradients exceeding the maximum cw accelerating gradients by 30–40\% a significant reduction in the field emission was observed. This in turn allows higher accelerating gradients to be used in cw as well. We attribute this behaviour to an rf-processing of the cavity surface which burns off field emitters.
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| WEPLS043 |
Progress of the Rossendorf SRF Gun Project
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2469 |
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- D. Janssen, A. Arnold, H. Buettig, R. Hempel, 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
- W.-D. Lehmann
IfE, Dresden
- J. Stephan
IKST, Drsden
- V. Volkov
BINP SB RAS, Novosibirsk
- I. Will
MBI, Berlin
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In this paper we report the status and the progress of the superconducting RF gun project in Rossendorf. The gun is designed for cw operation mode with 1 mA current and 10 MeV electron energy. The cavity consists of three cells with TESLA geometry, a special designed half-cell in which the photo cathode will be inserted and a choke filter, which prevents the leakage of RF power by the coaxial line between the cathode and the cavity cell. A double tuner allows the tuning of the half-cell and the TESLA cells separately. In 2005 the fabrication of two cavities with RRR300 and RRR40 was finished. We present the results of the field measurement and the warm tuning of the cavity cells as well as the tuning and performance measurement of the choke filter. The fabrication of the double tuner has been also finished. In a test bench we measured the properties of the tuner (tuning range, resolution) at LN2 temperature. Further activities concern the diagnostic beam line of the gun, the new cathode preparation and cathode transfer system, the driver laser and the LHe transfer line.
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| MOPCH161 |
Development of a Prototype Superconducting CW Cavity and Cryomodule for Energy Recovery
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436 |
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- P.A. McIntosh, C.D. Beard, D.M. Dykes, B. Todd
CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
- S.A. Belomestnykh
Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
- A. Buechner, P. Michel, J. Teichert
FZR, Dresden
- J.M. Byrd, J.N. Corlett, D. Li
LBNL, Berkeley, California
- T. Kimura, T.I. Smith
Stanford University, Stanford, Califormia
- M. Liepe, V. Medjidzade, H. Padamsee, J. Sears, V.D. Shemelin
Cornell University, Ithaca, New York
- D. Proch
DESY, Hamburg
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Energy Recovery LINAC (ERL) and LINAC-driven FEL proposals and developments are now widespread around the world. Superconducting RF (SRF) cavity advances made over the last 10 years for TESLA/TTF at 1.3 GHz, in reliably achieving accelerating gradients >20 MV/m, suggest their suitability for these ERL and FEL accelerators. Typically however, photon fluxes are maximised from the associated insertion devices when the electron bunch repetition rate is as high as possible, making CW-mode operation at high average current a fundamental requirement for these light sources. Challenges arise in controlling the substantial HOM power and in minimizing the power dissipated at cryogenic temperatures during acceleration and energy recovery, requiring novel techniques to be employed. This paper details a collaborative development for an advanced high-Qo cavity and cryomodule system, based on a modified TESLA cavity, housed in a Stanford/Rossendorf cryomodule. The cavity incorporates a Cornell developed resistive-wall HOM damping scheme, capable of providing the improved level of HOM damping and reduced thermal load required.
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