Numerical study of the normal current density behaviour in a narrow - gap glow discharge

A numerical study of normal glow discharge properties was performed in the case of small electrodes separations (0.05-0.4 cm) and moderate gas pressures (10-46 Torr). A recently observed new experimental effect of a considerable reduction in the normal current density for smaller discharge lengths was analyzed both by means of 2D fluid model and by a minimal 1D drift model of gas discharge. A good agreement between theoretical and experimental behaviour was demonstrated. An influence of the electrodes separation and of the gas heating on the value of the normal current density is discussed.