On the spatio-temporal dynamics of a self-pulsed nanosecond transient spark discharge: a spectroscopic and electrical analysis

Abstract

A self-pulsing discharge in flowing argon is investigated by means of electrical, optical and spectroscopic methods. The dependence of the discharge self-pulsing frequency on external parameters (applied negative dc voltage, gap dimensions) is determined, and optical and spectroscopic methods are used to investigate the discharge development with high spatial and temporal resolution. High-resolution spectroscopic measurements at several wavelengths reveal the complex dynamics of the transient spark discharge: a pre-phase at the needle tip and capillary edge, propagation of positive and negative streamers, creation of a transient glow discharge structure and a long-lasting afterglow. Excited plasma species necessary for the treatment of an exposed sample continue to be present even 80 µs after the breakdown of the active plasma.