Electron Collision Cross-Section Data for Plasma Modeling

An overview of the current status in electron collision cross section databases for plasma modeling is presented. Emphasis is on dissociation, ionization, and dissociative ionization. The effect of the operating conditions on the relative importance of different collision mechanisms is discussed. For high density plasmas with low gas pressure, a second collision with electrons becomes likely and metastable states may play a role in the dissociation and ionization processes. A number of outstanding theoretical and experimental issues in the cross-section data are discussed. For the total ionization cross section, a four-parameter fitting formula is found to represent the numerical data well and the parameters for some molecules used in plasma modeling are presented. Index Terms--Chemistry, collision processes, database reliability, electrons, impact ionization, plasma properties.