Collision induced heating of a weakly ionized dilute gas in steady flow

Collision induced heating is a sequence of collisional excitation and relaxation processes initiated by electron impact excitation and resulting in an increase in gas temperature. In this work, a suitable working fluid is identified and the efficacy of collision induced heating in a low pressure, microwave frequency electrical discharge environment is evaluated. After consideration of several low molecular weight diatomic gases, molecular hydrogen is selected as the working fluid of choice on the basis of the presence of several open scattering channels that result in kinetically excited products especially that of dissociation via excitation of the b3Σ/sub u/+ state. The kinetic energy distributions of the distributions of the products are calculated in the Condon reflection approximation for dissociation from X1Σ/sub g/+ (v = 0-13. The Franck-Condon envelope for v = 0 is in good agreement with previous works. Average product kinetic energies range from 6.19 ev for X1Σ/sub g/+ (v = 0) to 9.61 ev for X1Σ/sub g/+ (v = 13). Calculations involving two distinct reactor models for H2 in steady flow at 100 to 700 N/m2 indicate that the high energy dissociation products make a major contribution to gas heating. The existence of a threshold for equilibration of vibrational and kinetic temperatures is also indicated. In another set of calculations the self-consistent electron gas and neutral gas properties are calculated by simultaneous solutions of the Boltzmann equation and macroscopic balance equations