On basic processes sustaining constricted glow discharge in longitudinal N2 flow at atmospheric pressure

The results of numerical calculations on a steady-state constricted discharge in N-2 flow at atmospheric pressure are presented. Basic elementary processes responsible for sustaining the constricted discharge at low and high currents are found. It is shown that the charged particle generation in both regimes is controlled predominantly by an associative ionization N-2(A) + N-2(a') -> N-4(+) + e. However, metastable states are created in these regimes by different processes. In low-current discharge N-2(A) and N-2(a') metastables are created due to mutual collisions of the vibrationally excited molecules, and their collision frequency is determined by the vibration energy distribution function. In high-current discharge these metastables are excited by energetic electrons, and inelastic collision frequency is determined by the electron energy distribution function. The charged particle dynamic balance in the high-current constricted discharge in atmospheric pressure N-2 is non-local and sustained by ionization and ambipolar diffusion like that in a low-current diffusive discharge in a tube at low pressure. It was demonstrated that blowing of the discharge by longitudinal gas flow leads to a more pronounced constriction.