Regular Article

Time-dependent coupled kinetics and gas temperature in N₂-NO pulsed discharges

¹ Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
² Departamento de Engenharia Física, Faculdade de Engenharia, Universidade do Porto, R. Dr. Roberto Frias, 4200-465 Porto, Portugal
³ FOM Institute DIFFER, Eindhoven, The Netherlands
⁴ Eindhoven University of Technology, Department of Applied Physics, Eindhoven, The Netherlands

^a e-mail: cdp@fe.up.pt

Received: 1 April 2016
Revised: 14 June 2016
Accepted: 6 September 2016
Published online: 10 October 2016

Abstract

A self-consistent time-dependent kinetic model coupled to the gas thermal balance equation is presented for a N₂-1%NO millisecond pulsed DC discharge at a pressure of 266 Pa (2 Torr) and a current of 35 mA. The model provides the temporal evolution of the most important heavy species of interest to this work such as N₂(X¹Σ_g⁺, v), NO(X²Π), N₂(A³Σ_u⁺), N₂(a′¹Σ_u^-), N(⁴S) and O(³P), simultaneously with the time-dependent variation of the gas temperature. Predicted results for NO number densities during the pulse are compared to experimental ones measured by time-resolved quantum cascade laser absorption spectroscopy (QCLAS). The agreement between experiment and modelling predictions is very reasonable, mainly until a pulse duration of 2 ms, revealing the temporal evolution of the most important creation and loss mechanisms of NO(X). Simulations show a slow gas heating during the first millisecond. Thereafter, gas heating is accelerated and levels off at a time ~ 40 ms. These effects are explained and discussed in detail, together with the analysis of the fraction of the discharge power transferred to gas heating.