Propagation process and time history of electron energy of pulsed discharge in coaxial electrode in nitrogen

Pulsed discharge plasmas which are one of the non-thermal plasma have received much attention as an abundant radical source. Pulsed discharge is mainly divided into two phases. One is streamer discharge which has streamer head with very high electron energy, and the other is glow-like discharge which discharge between electrodes uniformly [1]. Many types of radical are produced by streamer head. On the other hand, in glow-like discharge, many radicals are produced by high electron density. However, some physical characteristics of pulsed discharge such as time history of electron energy, electron temperature still unclear. In this work, propagation process and time history of electron energy for radial direction of pulsed discharge in coaxial electrode were observed by using high-speed digital framing camera and emission spectroscopy, respectively. In the experiment, pulse generator consists of a Blumlein line and a pulse transformer. Blumlein line has 400 ns of pulsed duration, and pulse transformer has 1 to 3 of winding ratio. A coaxial type electrode has inner 0.5 mm diameter, 60 mm of outer diameter and 10 mm of length. The feeding gas into the coaxial electrode was nitrogen in this experiment. The framing images show that streamer discharge were initiated at the inner electrode and terminated at the outer electrode. Therefore, the results were observed the change from streamer discharge to glow-like discharge, too. In this paper, it will be reported propagation process and time history of pulsed discharge.