| Paper | Title | Page |
|---|---|---|
| WEPMN089 | A General Model of High Gradient Limits | 2236 |
|
||
|
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 |
||
| WEPMN090 | Recent RF Results from the MuCool Test Area | 2239 |
|
||
|
Funding: Supported by the USDOE Office of High Energy Physics The MuCool Experiment has been continuing to take data with 805 and 201 MHz cavities in the MuCool Test Area. The system uses rf power sources from the Fermilab Linac. Although the experimental program is primarily aimed at the Muon Ionization Cooling Experiment (MICE), we have been studying the dependence of rf limits on frequency, cavity material, high magnetic fields, gas pressure, coatings, etc. with the general aim of understanding the basic mechanisms involved. The 201 MHz cavity, essentially a prototype for the MICE experiment, was made using cleaning techniques similar to those employed for superconducting cavities and operates at its design field with very little conditioning. |