Study of the homogeneous glow-like discharge in nitrogen at atmospheric pressure

Abstract

Experimental investigation of the electrical and optical discharge characteristics is performed in the barrier discharge in nitrogen at 50 Hz. The time dependences of the current and the applied voltage are measured. Short-time photographs of the light intensity distribution in the discharge are obtained. When the frequency of the external voltage is low and dielectric barriers made of ‘Mylar’ are used, it is possible to obtain a homogeneous form of the discharge. During the pulse, the discharge current reaches the value of some amperes, and the maximum power is of the order of some tens of kilowatts. The appearance of a homogeneous discharge is interpreted as the widening of a single-electron avalanche due to photoemission. On the basis of a two-dimensional fluid model, the possibility of the initiation of the discharge by a narrow avalanche is demonstrated. It is shown that the observed discharge is a glow discharge, where the space charge plays a crucial role. The discharge passes successively through the Townsend phase, the streamer phase, the phase of radial expansion and, finally, the afterglow phase. The theory predicts that the distribution of the light intensity in the phase of discharge expansion must have the form of a ring widening in time. The properties of the power supply play an important role in the model. A comparison between the theoretical and experimental results shows good agreement.