Current near the insulator wall in plasma accelerators
A model of plasma acceleration taking into account the erosion of an insulator wall at the base of the accelerator is studied. The total current is considered as divided into two parts: the propagating head current and a stationary arc near the insulator wall. While a reverse current appears at the base of the accelerator during the second quarter-period, the current in the front flows in the initial direction even after the half period of the total current. Separated blobs of impurities are created. Dependences of both currents and velocity on the circuit and accelerator parameters are investigated. The results are in an agreement with experiments.