Role of ions in a crossed-field diode II: Monte Carlo collisions

Abstract

Summary form only given: The effect of ions in a magnetically insulated crossed-field gap is studied using a particle-in-cell simulation with Monte Carlo collisions (MCC). (Code available through the PTSG at UC Berkeley.) These results are compared with the predictions from single particle orbit, shear flow models and previous particle-in-cell simulations in which the ions were modeled as a sheet of charge fixed at different positions within the gap. The results of this experiment indicate that the diode loses insulation much more rapidly than shown in the immobile ion sheet model. The reasons for this increased rate of electron migration toward the anode are that the ions in this simulation are mobile and that the effects of MCC are being taken into account. Thus, ambipolar transport plays a role in the migration as does the fact that ions are being created throughout the gap by collisions. The implications of these findings, as suggested in previous work, are that of pulse shortening in relativistic magnetrons and bipolar flows in pulsed power systems.