Modeling Breakdown Processes in RF Cavities Using Particle-in-cell (PIC) Codes

Design of future accelerators can benefit from the use of high gradient RF electric fields (>50 MV/m) and operating under strong applied magnetic fields (>2.5 T). These large fields help to minimize the number of costly accelerating elements needed for the neutrino experiments. However a main limitation in applying such large fields in the design of accelerators is the physical breakdown of metallic structures. We have developed computer models of the process of breakdown using OOPIC Pro, a 2-dimensional particle-in-cell (PIC) code in order to understand the physical processes that are responsible for breakdown and test methodologies to mitigate the problem. We describe here the results of our numerical experiments including the effects of applied magnetic field strength and direction on the breakdown process, sensitivity of breakdown triggers on field emission parameters, and the potential to measure the onset of breakdown by examining impurity radiation.