Numerical simulation of a low‐density plasma erosion opening switch

Current conduction through a low density (∼1012 cm−3) collisionless plasma injected between two coaxial conducting cylinders is simulated using a 2 (1)/(2) ‐D, electromagnetic particle‐in‐cell code. Plasma is injected through the anode towards the cathode with flow velocity, VF, and is assumed to be azimuthally symmetric. Current is driven through the plasma so that the 100 kA level is reached in ≂5 nsec. The opening process, when current is diverted to a load, is also treated. Electrons are found to carry current in a narrow current channel across the plasma by E×B drift. A large electric field is established by charge separation in the plasma in order to provide the drift. The motion of the anode end of the current channel controls the time of opening and is found to be independent of VF and to depend strongly on density and length.