Efficient H-Production under Nonequilibrium Conditions

Abstract

Electron energy distribution functions for typical conditions in hydrogen electrical discharges are calculated by numerically solving the Boltzmann transport equation. It is then possible to determine that the input energy is channeled predominantly into vibrational excitation. Because the dissociative attachment cross section is a very strong function of the initial vibrational state, high vibrational temperatures are found to increase markedly the formation rate of negative ions. Self-consistent solutions for the excited state populations, the electron energy distribution, and the rate of dissociative attachment are obtained. It is further determined that when the gas temperature is much lower than the vibrational temperature, anharmonic pumping increases the population of the higher vibrational levels over that of Boltzmann equilibrium. Conditions of high vibrational excitation and low translational temperature result in dissociative attachment rates three orders of magnitude larger than that from the ground vibrational state. Experiments to achieve these results are suggested.