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

Pulsed discharge plasmas, a type of non-thermal plasma, have received much attention as an abundant radical source. Pulsed discharge is mainly divided into two phases: A streamer discharge, which has a streamer head with very high electron energy; and a glow-like discharge, which forms between electrodes uniformly. Many types of radical are produced by the streamer head, while the glow-like discharge produces many radicals due to high electron density. However, various physical characteristics of pulsed discharge such as time history of electron energy and electron temperature remain unclear. This work observes the propagation process and time history of electron energy for radial direction of pulsed discharge in a coaxial electrode using high-speed digital framing camera and emission spectroscopy. In the experiment, the pulse generator consists of a Blumlein line and a pulse transformer. The Blumlein line has 400 ns of pulsed duration, and pulse transformer has a winding ratio of 1 to 3. The coaxial-type electrode has an inner diameter of 0.5 mm, an outer diameter of 60 mm, and a length of 10 mm. The feeding gas into the coaxial electrode was nitrogen in this experiment. Framing images show that streamer discharges were initiated at the inner electrode and terminated at the outer electrode. Therefore, the results were also able to observe the change from streamer discharge to glow-like discharge. This paper will report the propagation process and time history of pulsed discharge.