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| FPAT021 |
Experience with Kicker Beam Coupling Reduction Techniques
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1742 |
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- E.H.R. Gaxiola, J. Bertin, F. Caspers, L. Ducimetière, T. Kroyer
CERN, Geneva
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SPS beam impedance is still one of the worries for operation with nominal LHC beam over longer periods once the final configuration will be installed in 2006. Several CERN SPS kickers suffer from significant beam induced ferrite heating. In specific cases, for instance beam scrubbing, the temperature of certain ferrite yokes went beyond the Curie point. Several retrofit impedance reduction techniques have been investigated theoretically and with practical tests. We report on experience gained during the 2004 SPS operation with restively coated ceramic inserts in terms of kicker heating, pulse rise time, operating voltage, and vacuum behavior. For another technique using interleaved metallic strips we observed significant improvements in bench measurements. Advantages and drawbacks of both methods and potential combinations of them are discussed and simulation as well as measured data are shown. Prospects for further improvements beyond 2006 are briefly outlined.
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| FPAT022 |
Performance of the CERN SPS Fast Extraction for the CNGS Facility
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1757 |
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- E.H.R. Gaxiola, G. Arduini, W. Höfle, F. Roncarolo, E. Vogel, E. Vossenberg
CERN, Geneva
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The SPS LSS4 fast extraction system will serve both the anti-clockwise ring of the LHC and the long baseline neutrino (CNGS) facility. For the latter two extractions spaced by 50 ms, each affecting half of the ring, are foreseen. During the shutdown 2003-2004 the performance of the fast extraction kickers was improved in order to match more closely the specifications for the kicker pulse shape required for the CNGS and LHC extractions. The rise and fall times were significantly reduced, as well as the post-pulse kick ripple. However, the latter remains outside specifications and oscillations are induced in the leading bunches of the batch remaining in the machine at the moment of the first extraction. While further improving the characteristics of the kicker pulse shape, the possibility of damping the beam oscillations using the transverse feedback system has been explored. We report on the recent pulse form improvements and results of beam tests.
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