| Paper | Title | Page |
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| WEPMN089 | A General Model of High Gradient Limits | 2236 |
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Funding: Supported by the USDOE / Office of High Energy Physics
Recent experimental work done to develop high gradient, low frequency cavities for muon cooling, has led to a model of rf breakdown and high gradient limits in warm structures. We have recently been extending this model to try to explain some superconducing rf quench mechanisms, as well as DC and dielectric breakdown. The model assumes that the dominant mechanisms in warm metal systems are fractures caused by the the electric tensile stress, and surface micro-topography that is strongly determined by the the cavity design and history*. We describe how these processes can determine all measurable parameters in warm systems. With superconducting systems, these mechanisms also apply, however field emission, impurities and temperature produce a somewhat different picture of quenching and pulsed power processing. We describe the model and some recent extensions and improvements in some detail and a variety of results accelerators and other applications.
* Hassanein et. al. Phys. Rev. STAB, 9, 062001 |
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| THPAS008 | Simulation of the Dynamics of Microwave Transmission Through an Electron Cloud | 3525 |
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Funding: Work supported by the U. S. DOE under Contract no. DE-AC02-05CH11231
Simulation studies are under way to analyze the dynamics of microwave transmission through a beam channel containing electron clouds. Such an interaction is expected to produce a shift in phase accompanied by attenuation in the amplitude of the microwave radiation. Experimental observation of these phenomena would lead to a useful diagnosis tool for electron clouds. This technique has already been studied* at the CERN SPS. Similar experiments are being proposed at the PEP-II LER at SLAC as well as the Fermilab MI. In this study, simulation results will be presented for a number of cases including those representative of the above mentioned experiments. The code VORPAL is being utilized to perform electromagnetic particle-in-cell (PIC) calculations. The results are expected to provide guidance to the above mentioned experiments as well as lead to a better understanding of the problem.
* T. Kroyer, F. Caspers, E. Mahner , pg 2212 Proc. PAC 2005, Knoxville, TN |