Modeling RF window breakdown: From vacuum multipactor to RF plasma

Plasma breakdown at dielectric windows in the output of high power microwave systems has become an important challenge with the advent of GW power level sources. The modeling and simulations have played a crucial role in understanding the physics of plasma breakdown. In this work, we report a number of recent advances which have significantly improved understanding of the physics of vacuum multipactors, gaseous discharges driven by microwaves, and the transition from one regime to the other by varying the gas pressure.