Kinetic Modeling of RF Breakdown in High-Pressure Gas-filled Cavities
- Fermilab
- LBL, Berkeley
- MUONS Inc., Batavia
- Voss Sci., Albuquerque
Recent studies have shown that high gradients can be achieved quickly in high-pressure gas-filled cavities without the need for long conditioning times, because the dense gas can dramatically reduce dark currents and multipacting. In this proj ect we use this high pressure technique to suppress effects of residual vacuum and geometry found in evacuated cavities to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of radiofrequency and surface preparation. A series of experiments at 805 MHz using hydrogen fill pressures up to 0.01 g/cm3 of H2 have demonstrated high electric field gradients and scaling with the DC Paschen law limit, up to ~30 MV/m, depending on the choice of electrode material. For higher fi eld stresses, the breakdown characteristics deviate from the Paschen law scaling. Fully-kinetic 0D collisional particle-in-cell (PIC) simulations give breakdown characteristics in H2 and H2/SF6 mixtures in good agreement with the 805 MHz experimental resu lts below this field stress threshold. The impact of these results on gas-filled RF accelerating cavity design will be discussed.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 1419179
- Report Number(s):
- FERMILAB-CONF-12-627-E; IPAC-2012-THPPC028; 1126771
- Journal Information:
- Conf.Proc., Vol. C1205201; Conference: 3rd International Particle Accelerator Conference, New Orleans, Louisiana, 05/20-05/25/2012
- Country of Publication:
- United States
- Language:
- English
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