Basic physics of gaseous dielectrics

Basic physical processes involved in the prebreakdown stages of gaseous dielectrics are discussed, with particular emphasis on electron attachment, electron-molecule scattering, and electron impact ionization. Particular emphasis is placed on the dielectric properties of gases at moderately high pressures (few kilopascals to few atmospheres) and under uniform DC conditions for which the electrons generated in the gas quickly reach a steady state, and thus electron-molecule interactions leading to electrical breakdown can be addressed assuming steady-state conditions even though the breakdown itself is a transient, nonequilibrium phenomenon. Utilization of the understanding of these basic processes for tailoring gases/mixtures with optimum dielectric strengths is indicated