Dark current simulations in accelerating structures driven by short RF pulses

Recent experimental demonstrations have shown that accelerating structures driven by short RF pulses lasting only a few nanoseconds can achieve significantly higher gradients compared to conventional RF accelerators. One of the primary challenges in high-gradient operation, RF breakdown, can be mitigated on a timescale two orders of magnitude shorter than what is typically used in klystron-driven RF accelerators. To gain a physics understanding of RF breakdown in the short-pulse regime, we conducted dark current simulations in a few accelerating structures, investigating field emission and multipacting phenomena. Our preliminary simulations revealed that the low dark current in the short-pulse regime holds promise for a new class of accelerators designed to operate with short pulses.