Dynamics and stability of the Townsend discharge in nitrogen in narrow gaps

This paper investigates the dynamics of the Townsend discharge in nitrogen in narrow gaps. To provide stability of discharge in a broad range of current, we apply a plane-parallel structure, one of the electrodes of which is made of a high-resistivity gallium arsenide. The results of experiments are analyzed in the framework of theory [Yu. P. Raizer et al., Tech. Phys. 51, 185 (2006)], which considers the dynamics of discharge in short nitrogen-filled gaps of similar structures. According to the theory, a key parameter of discharge dynamics is time ϑ that defines the rate of discharge response to perturbations. In our work, time ϑ is experimentally found by analyzing the noise spectrum of the discharge glow in the stable and spatially uniform state of the structure. This characteristic time depends linearly on the discharge gap width, which corroborates conclusions based on the standard model of Townsend discharge. However, its values are substantially shorter compared to those predicted by theory. The relationship between ϑ and experimentally observed critical current density for the oscillatory instability, jcr, is applied to find the discharge negative differential resistance for a set of parameters of the discharge gap.