The DC gas discharge structure as a thermodynamic minimum

The formation of a glow discharge within a discharge gap set to the right of the Paschen minimum has the appearance of an instability which leads to a decrease of the gap potential together with an increase of current corresponding to the normal glow. The analysis presented shows that the stationary state of the discharge is obtained by minimizing the applied potential for a given electron avalanche size. A thermodynamic interpretation is proposed to clarify this behaviour. As a consequence, an explanation is found for the well known property of a normal glow discharge not limited by radial walls, to increase in current by increasing its cross section rather than increasing the current density.