Paper PS1-WeA8
A Global (Volume Averaged) Model of the Chlorine Discharge

Wednesday, November 11, 2009, 4:20 pm, Room A1

A steady state global (volume averaged) model is developed for the chlorine discharge using a revised reaction set [1]. Various calculated plasma parameters are compared to measurements found in the literature, showing a good overall agreement. The reaction rates for the various reactions are evaluated in the pressure range 1 - 100 mTorr. In particular we explore the dissociation process as well as the creation and destruction of the negative ions Cl^-. The discharge is highly dissociated throughout the pressure range explored, 1 - 100 mTorr, even when the absorbed power is low. The mechanism for Cl creation is complex, although electron impact dissociation dominates with roughly 50 - 60 % contribution. Dissociative electron attachment is also of importance and mutual neutralization is an important contributor to the production of Cl atoms at higher pressure. The electronegativity increases rapidly with decreasing dissociation fraction since the Cl- ions are created entirely by dissociative electron attachment, predominantly from Cl₂(v=0), but also up to 14 % from Cl₂(v>0) at 100 mTorr. The negative ion Cl^- is lost almost entirely through mutual neutralization with Cl₂⁺ at high pressure while Cl⁺ has a significant contribution at low pressure. Furthermore, the dilution by argon was explored. Dilution by argon decreases the electronegativity but increases the electron temperature, dissociation fraction and the fractional density of Cl⁺ ions significantly.

[1] E. G. Thorsteinsson and J. T. Gudmundsson, A global (volume averaged) model of the chlorine discharge, Plasma Sources Sci. Technol., submitted 2009