Calculated gas temperature profiles in argon glow discharges

We use a previously developed model for the electrical properties of glow discharges, coupled to a Monte Carlo simulation of the heavy particles (ions and fast neutrals) in the cathode sheath region, to calculate the gas heating source term in glow discharges in argon with planar electrodes. The gas temperature profile is calculated from the one-dimensional heat transport equation, and we report results for discharge current densities up to 4 mA/cm(2) for a value of pd (product of the gas pressure and gap spacing) of 1.5 Torr cm. The gas temperature peaks at a position slightly inside the cathode sheath, and at the highest current density reported here the gas temperature reaches 354 K. A large fraction of the energy gained by the ions in the sheath is transported directly to the cathode (mostly through fast neutrals), and the fractional ion energy converted to thermal motion of the gas decreases with increasing current density. We report some results to show the dependence of the gas temperature on the thermal accommodation coefficient. For a constant current, the calculated discharge voltage is somewhat higher when gas heating is taken into account. (C) 2000 American Institute of Physics. [S0021-8979(00)03218-7].