| Title |
Ultra High Gradient Breakdown Rates in X-Band Cryogenic Normal Conducting Rf Accelerating Cavities |
| Authors |
- A.D. Cahill, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
- V.A. Dolgashev, S.G. Tantawi, S.P. Weathersby
SLAC, Menlo Park, California, USA
|
| Abstract |
RF breakdown is one of the major factors limiting the operating accelerating gradient in rf particle accelerators. We conjecture that the breakdown rate is linked to the movements of crystal defects induced by periodic mechanical stress. Pulsed surface heating possibly creates a major part of this stress. By decreasing crystal mobility and increasing yield strength we hope to reduce the breakdown rate for the same accelerating gradient. We can achieve these properties by cooling a copper accelerating cavity to cryogenic temperatures. We tested an 11.4 GHz cryogenic copper accelerating cavity at high power and observed that the rf and dark current signals are consistent with Q₀ changing during rf pulses. To take this change in Q₀ into account, we created a non-linear circuit model in which the Q₀ is allowed to vary inside the pulse. We used this model to process the data obtained from the high power test of the cryogenic accelerating structure. We present the results of measurements with low rf breakdown rates for surface electric fields near 500 MV/m for a shaped rf pulse with 150 ns of flat gradient.
|
| Funding |
Work Supported by DOE/SU Contract DE-AC02-76-SF00515, US NSF Award PHY-1549132, the Center for Bright Beams, and DOE SCGSR Fellowship. |
| Paper |
download THPIK125.PDF [1.133 MB / 4 pages] |
| Export |
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| Conference |
IPAC2017, Copenhagen, Denmark |
| Series |
International Particle Accelerator Conference (8th) |
| Proceedings |
Link to full IPAC2017 Proccedings |
| Session |
Posters Thursday 2 |
| Date |
18-May-17 16:00–18:00 |
| Main Classification |
07 Accelerator Technology |
| Sub Classification |
T06 Room Temperature RF |
| Keywords |
accelerating-gradient, cryogenics, cavity, experiment, electron |
| Publisher |
JACoW, Geneva, Switzerland |
| Editors |
Volker RW Schaa (GSI, Darmstadt, Germany); Gianluigi Arduini (CERN, Geneva, Switzerland); Juliana Pranke (ESS, Lund, Sweden); Mike Seidel (PSI, Villigen, Switzerland); Mats Lindroos (ESS, Lund, Sweden) |
| ISBN |
978-3-95450-182-3 |
| Published |
May 2017 |
| Copyright |
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