| Paper |
Title |
Page |
| TUAZ05 |
Comparison of Graphite and Diamond Structured Carbon Stripper Foils under Operational Conditions at the Los Alamos PSR
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112 |
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- T. Spickermann, M. J. Borden, R. J. Macek
LANL, Los Alamos, New Mexico
- C. S. Feigerle
University of Tennessee, Knoxville, Tennessee
- R. W. Shaw
ORNL, Oak Ridge, Tennessee
- I. Sugai
KEK, Ibaraki
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In the Los Alamos Proton Storage Ring H–Ions merge with circulating protons in a bending magnet and are stripped of their two electrons in a carbon stripper foil. The circulating protons continue to interact with the foil. Despite efforts to minimize the number of these foil hits, like “painting” of the vertical phase space, they can not totally be eliminated. As a result foil heating and radiation damage limit the lifetime of these foils. In recent years LANL has collaborated with KEK to improve the graphite foils in use at PSR and these foils now last typically for two months. Recently an alternative in the form of diamond structured carbon foils has been proposed for use at SNS. Depending on the grain size these are referred to as microcrystalline or nanocrystalline foils. Both types have been tested in PSR, with quite different results. While the microcrystalline foil failed catastrophically before production beam currents were reached the nanocrystalline foil was successfully used in normal operation for several weeks. Advantages of the diamond foil concept as well as some noteworthy differences that we observed with respect to the LANL graphite foils will be discussed here.
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| THAW04 |
Experimental Characterization of the “1st Pulse” e-p Instability at the LANL PSR
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311 |
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- R. J. Macek, A. A. Browman, D. H. Fitzgerald, R. C. McCrady, T. Spickermann, J. Zaugg
LANL, Los Alamos, New Mexico
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A puzzling aspect of the e-p instability at PSR is the so called “1st Pulse” instability phenomenon. It shows up on the first beam pulse after a period (10 to 30 minutes or more) of beam off time. This pulse has a significantly lower threshold than subsequent beam pulses that follow with the standard time separation. While the standard PSR operation for Lujan Center operation is unaffected by this phenomenon, it does interfere with some high intensity, single pulse experiments using PSR beam. We will summarize the present experimental data characterizing this phenomenon as compared with the typical e-p instability observed at higher repetition rates at PSR and discuss some possible explanations.
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