Some fundamental aspects of glow discharges in plasma-assisted processes

The applicability of some theoretical models for ionization-assisted processes, such as those of Davis and Vanderslice and Child-Langmuir, are discussed using data obtained by the authors and other researchers in the field. Information derived from argon discharges is used as a basis, and provides a convenient foundation from which to compare different system layouts, such as the direct current diode, and various triode systems. Detailed information is given on the estimation of the cathode fall distance L and the L/λ ratio, where λ is the mean free path for charge exchange collision. This allows the estimation of energy distributions for both ions and neutrals. Other important parameters are also discussed, such as ionization efficiency, as well as the effect of additional species within the discharge.