Condition for the homogeneity of a glow discharge in a dense unbounded gas

Conditions for the formation of ionization-overheating instability in the glow discharge in a molecular gas laser are examined. It is shown that this instability arises due to some fluctuation process leading to a local increase in energy dissipation (in the form of Joule heat) and to isobaric expansion of the gas, if the two following conditions are met: (1) the initial fluctuation has the right direction, and sufficient amplitude and duration, and size of the gas region it has captured; and (2) there is a positive feedback mechanism which leads to additional energy dissipation conditioned by gas expansion. This type of instability is studied for the cases of pure CO and N2.