Model for a glow discharge in flowing nitrogen

Abstract

A two-dimensional model of the positive column of a glow discharge in flowing nitrogen is presented. The model is applicable to a cylindrically symmetric and axially nonuniform weakly ionized discharge. Nitrogen ionization mainly results from associative ionization occurring in the collisions of metastable molecules in the a′1Σ−u and A3Σ+u electronic states. Gas heating explains the lowering of the electric field as the current increases or the flow velocity decreases. Under most conditions, vibrational deactivation results from superelastic collisions between excited molecules and electrons. Electric field, discharge voltage, vibrational and electronic populations, and gas temperature, are calculated as a function of pressure, flow velocity, diameter and length of the discharge, and current. Quantitative comparisons with available experimental data are made. Good agreement is observed for discharges at low pressures in gas flows with low Reynolds numbers.