Kinetic modeling of low-pressure nitrogen discharges and post-discharges

¹ Centro de Física dos Plasmas, Instituto Superior Técnico, 1049-001 Lisboa, Portugal
² Dep. de Física, Faculdade de Engenharia, Universidade do Porto, 4200-465 Porto, Portugal

Corresponding author: vguerra@alfa.ist.utl.pt

Received: 5 July 2004
Accepted: 31 August 2004
Published online: 3 November 2004

Abstract

The kinetic modeling of low-pressure ( torr) stationary nitrogen discharges and the corresponding afterglows is reviewed. It is shown that a good description of the overall behavior of nitrogen plasmas requires a deep understanding of the coupling between different kinetics. The central role is played by ground-state vibrationally excited molecules, N₂, which have a strong influence on the shape of the electron energy distribution function, on the creation and destruction of electronically excited states, on the gas heating, dissociation and on afterglow emissions. N₂ molecules are actually the hinge ensuring a strong link between the various kinetics. The noticeable task done by electronically excited metastable molecules, in particular N₂ and N₂, is also pointed out. Besides contributing to the same phenomena as vibrationally excited molecules, these electronic metastable states play also a categorical role in ionization. Furthermore, vibrationally excited molecules in high v levels are in the origin of the peaks observed in the flowing afterglow for the concentrations of several species, such as N₂, N₂, N₂⁺ and electrons, which occur downstream from the discharge after a dark zone as a consequence of the V-V pumping-up mechanism.