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

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(X1Σg +, v), NO(X2Π), N2(A3Σu +), N2(a′1Σu -), 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