A comparative study of negative glow discharge models

Summary form only given, as follows. The interactions of thermionic oxide cathode with the surrounding high density negative glow plasma is of interest to low pressure fluorescent lamp research and development for a long time. The basic mechanism for negative glow formation can be described by the fact that thermionic electrons accelerated through the cathode fall and undergo excitations and ionizations in the negative glow region of low electric fields. The energy distribution of high energy electron group in the weak field negative glow region was first measured by Waymouth (1959). Only recently, a more quantative ambipolar diffusion theory of hot-cathode negative glow discharge was developed by Ingold, where the distribution of plasma density and electric field could be determined. In this work, a full numerical drift-diffusion model for high energy beam electrons, plasma electrons and ions including Poisson equation for electric field without the assumption of ambipolarity will be reported. The effect of space charge field on the beam electron transport can be accessed. The preliminary results showed that the beam electron penetrate further into the negative glow compared with the Ingold´s model under the same conditions. In addition locations of maximum plasma density and the field reversal were also shifted further away from the cathode in comparison.