Numerical simulations of glow discharges.

摘要

The research presented here has focused on developing numerical simulations that are capable of providing kinetic-level information about the transport of charged particles in glow discharges that are of interest in the materials processing industry.; A variety of hybrid kinetic-fluid models for dc discharges are studied in the first part of this work. These simulations indicate that beam models (single beam and multi-beam) for fast electrons in a dc glow can produce qualitatively correct results. Accurate comparisons to experiment are possible with a hybrid particle-fluid approach. This technique is further used to simulate H{dollar}sb2{dollar} dc discharges under conditions typical in diamond film deposition reactors. Model predictions compare favorably with experimental measurements. These systems exhibit anode glows, which appear to be an important source of the atomic hydrogen that reaches the anode, where diamond films are typically grown.; In the second part of this work, the particle-in-cell/Monte Carlo scheme, which is a purely kinetic technique, is used to study a wide variety of phenomena in rf glow discharges. Simulation results indicate that the spatio-temporal evolution of ionization rate is quite sensitive to the dominant discharge sustaining mechanism. These simulations have also been used to establish scaling laws for discharges in which secondary electron emission is not important. A study of electron transport in low pressure discharges revealed the possibility of very low average electron energies and negative bulk electron power deposition. A simple two fluid model of fast and slow electrons suggests fast electron transport in these systems is dominated by density gradients and not the local electric field.