Kinetic processes initiated by a nanosecond high-current discharge in hot air

Results from numerical investigations of kinetic processes initiated by a pulsed nanosecond discharge in hot (T 0 ≥ 1000 K) air at atmospheric pressure are presented. The calculated results on the dynamics of the electron density, the population of the N2(B3Π g ) and N2(C3Π u ) states, and the atomic oxygen density in the axial discharge region agree with experiment. The method for determining the gas temperature by measuring the rotational structure of the transitions N2(C3Π u , ν) → N2(B3Π g , ν′) of the 2+ nitrogen system is analyzed. It is shown that, in relatively weak reduced electric fields typical of secondary discharge pulses, the electron impact excitation of the N2(C3Π u ) state from the ground state N2(X1Σ + ) can be accompanied by its additional step population from the N2(B3Π g ), N2(a′Σ − ), and other electronic states. This effect substantially influences the rotational distribution of nitrogen molecules in the N2(C3Π u , ν) state; moreover, the temperature determined from this distribution can be substantially higher than the true gas temperature.