Power-loading effects in gas-discharge models

The effect of the large discharge currents in the switch conduction stage on the transport and rate coefficients which appear in the rate equation for the electron density, the basic element in a discharge model was examined. It is indicated that for the current levels of interest there will be significant heating. The related changes due to enhanced populations in the high energy states of the gas molecules: modified rates for translational gas heating and for excitation, dissociation, and perhaps ioinization. It is concluded that the high energy tail of the electron energy distribution is affected. Rate coefficients are more sensitive to power loading of the gas than are the drift velocity, average electron energy, and diffusion rate. In terms of model predictions of switch performance, knowledge of the source function from the e-beam is important in calculations of switch current gain and for conductivities. These will be underestimated with the neglect of ionization produced by secondaries. The distribution function is modified at the high energies from its form characterized by E/N in the presence of the e-beam source. The subsequent changes in the rate coefficients due to the e-beam source and the excited state populations can affect the turn on time of the switch.