Propagation of plasma bullets in helium within a dielectric capillary—influence of the interaction with surfaces

Abstract

This paper reports an experimental study on the propagation of an ionization wave inside a thin capillary, called ‘plasma bullet’. A low-frequency sinusoidal voltage is applied and several bullets are emitted during each cycle. The delay between two successive discharges is short enough so the propagation of one bullet is influenced by the charges deposited on surfaces by the previous one. It was shown that the propagation length increases during the cycle. An interesting result is that a discontinuity during the propagation of a bullet has been clearly pointed out. When it crosses the discontinuity, the bullet has been shown to increase its light emission and its propagation velocity. It was explained by a transition between regions of different potential, due to charges deposited by the previous bullets.