Features of transient processes in DC microdischarges in molecular gases: from a glow discharge to an arc discharge with a unfree or free cathode regime

A unified self-consistent model is formulated to describe a discharge gap, electrodes, and the formation of the parameters of dc microdischarges in molecular gases at atmospheric pressure. Numerical experiments performed in the current density range from 90 to 2.5$\times$10$^6$ mA/cm$^2$ have revealed the dependence of the voltage drop on a discharge on the current density, which reproduces the formation of glow, transient from glow to arc, and arc regimes. It has been shown that a transition from the glow discharge to the arc discharge with a free and unfree cathode regime can be implemented depending on boundary conditions on the outer edges of electrodes.