| Paper |
Title |
Page |
| TUAX01 |
Accumulation of High Intensity Beam and First Observations of Instabilities in the SNS Accumulator Ring*
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59 |
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- V. V. Danilov, A. V. Aleksandrov, S. Assadi, W. Blokland, S. M. Cousineau, C. Deibele, S. Henderson, J. A. Holmes, M. A. Plum, A. P. Shishlo
ORNL, Oak Ridge, Tennessee
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The Spallation Neutron Source accumulator ring, designed to accumulate up to 1.5·1014 protons per pulse, was commissioned in January of 2006. During the run, over 1.·1014 protons were accumulated in the ring in the natural chromaticity state without any sign of instabilities. The first beam instabilities were observed for a high intensity coasting beam with zero chromaticity. Preliminary analysis of data indicates instabilities related to extraction kicker impedances, and electron-proton instability. Here we review the background theory and design philosophy of the ring, as it relates to instabilities, and compare the pre-commissioning predictions with the experimental measurements.
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| THAW03 |
RF Barrier Cavity Option for the SNS Ring Beam Power Upgrade
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298 |
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- J. A. Holmes, S. M. Cousineau, V. V. Danilov, A. P. Shishlo
ORNL, Oak Ridge, Tennessee
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RF barrier cavities present an attractive option for facilitating the path to higher beam intensity in the SNS power upgrade. Barrier cavities lead to flat longitudinal current densities, thus minimizing bunch factor effects. In addition to allowing more beam to be injected in this fashion, flat current profiles may lead to increased e-p instability thresholds due to reduced multipacting during the trailing stage of the bunch. Finally, it is possible to inject self-consistent beam distributions into barrier buckets, thus providing the additional advantages of uniform transverse beam density (good for meeting target constraints) and little or no halo (good for low losses). Simulations addressing all these issues will be presented and discussed.
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