Incorporating Collisions into the Limiting Current of a Crossed-Field Gap

Crossed-field devices, which have magnetic fields perpendicular to the electric field across the gap, are used for numerous high-power applications, such as Hall thrusters and high-power microwaves [1]–[2]. While previous studies have examined the limiting current of a crossed-field gap at vacuum [3], an assessment accounting for collisions has not been performed. Prior particle-in-cell (PIC) simulations showed that non-vacuum pressures can cause electrons emitted from the cathode to reach the anode even for magnetic fields above the Hull cutoff, which typically corresponds to the magnetic field above which emitted electrons turn back toward the cathode before crossing the gap [4]. However, these studies did not specifically address the limiting current of the gap.