| Paper |
Title |
Page |
| THP032 |
A Variable Directional Coupler for an Alternate ILC High-Power RF Distribution Scheme
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643 |
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- C. D. Nantista, C. Adolphsen
SLAC, Menlo Park, California
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We describe the design and functionality of an RF directional coupler for which the power division between the output ports is mechanically variable. In an alternate power distribution scheme for the ILC, power is delivered to cavities in pairs, through hybrids. Four pairs, or eight cavities, are fed from one waveguide feed, from which one fourth, one third, and one half of the power is coupled out at consecutive directional couplers. Three such feeds are powered by a single 10 MW klystron. Experience suggests that cavities considered useable will display some variation in the operational accelerating gradient they can sustain. With fixed distribution, the klystron power must be kept below the level at which the weakest cavity out of 24 receives its power limit. This problem can be solved by installing variable attenuators, but that means wasting precious power. With adjustable coupling, distribution can be optimized for more efficient use both of available power and of the accelerating cavities. This novel device, feeding cavities paired by similar performance, can provide such benefit to the ILC.
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| THP046 |
Status of 3.9-GHz Deflecting-Mode (CRAB) Cavity R&D
|
682 |
| |
- L. Bellantoni, H. Edwards, M. Foley, T. K. Khabiboulline, D. V. Mitchell, A. M. Rowe, N. Solyak
Fermilab, Batavia, Illinois
- C. Adolphsen
SLAC, Menlo Park, California
- G. Burt, A. C. Dexter
Cockcroft Institute, Lancaster University, Lancaster
- P. Goudket
CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
- T. W. Koeth
Rutgers University, The State University of New Jersey, Piscataway, New Jersey
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The superconducting 3.9GHz deflecting mode cavity design which has been under development as a beam slice diagnostic is planned for use as the ILC crab cavity. We describe the applications and review the status of the R & D, giving both prototype test results and computational studies of beam interaction.
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| THP078 |
High-Gradient Test of a Tungsten-Iris X-Band Accelerator Structure at NLCTA
|
764 |
| |
- S. Doebert, A. Grudiev, S. T. Heikkinen, J. A. Rodriguez, I. Syratchev, M. Taborelli, W. Wuensch
CERN, Geneva
- C. Adolphsen, L. Laurent
SLAC, Menlo Park, California
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The CLIC study group at CERN has built two X-band accelerating structures to be tested at SLAC in NLCTA. The structures consist of copper cells with insert irises made out of Molybdenum and Tungsten, clamped together and installed in a vacuum tank. These structures are exactly scaled versions from structures tested previously at 30 GHz and with short pulses (16 ns) in the CLIC Test Facility at CERN. At 30 GHz these structures reached gradients of 150 MV/m for Tungsten and 195 MV/m for Molybdenum. These experiments were designed to provide data on the dependence of rf breakdown on pulse length and frequency. This paper reports in particular on the high-gradient test of the tungsten-iris structure. At a pulse length of 16 ns a gradient of 125 MV/m was reached at X-band, 20 % lower than the 150 MV/m measured at 30 GHz in the CLIC Test Facility. The pulse length dependence and the dependence of the break down rate as a function of gradient were measured in detail. The results are compared to data obtained from the Molybdenum-Iris experiment at X-band which took place earlier as well as to 30 GHz data.
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