Effect of the plasma piston size on the efficiency of the electrodynamic acceleration of a body

The objective of the experiments reported here was to investigate the effect of the size of the plasma piston on velocity saturation during the electrodynamic acceleration of a body in rail-gun accelerators. An analysis of the results suggests that the observed decrease of the efficiency of the accelerating action of an expanded plasma piston is associated with the increased permeability of the piston with respect to the gas enclosed between the piston and the body. This conclusion is consistent with the concept of the plasma piston as a combination of merging and separating arc channels.