A reduced set of air plasma reactions for nanosecond pulsed plasmas

The reduction of a mechanism describing plasma chemistry for dry air has been carried out for conditions of nanosecond-pulsed discharge plasmas. The discharge conditions include both diffuse glow and filamentary spark modes. A reduced set for glow discharges is found to have inelastic electron-impact reactions of N₂ and O₂, quenching of excited N₂, electron attachment to O₂^-, ion conversion between N₂⁺, N₄⁺, O₄⁺, O₂⁺·N₂, and O₂⁺, and ion-ion and electron-ion recombination. When the discharge is in a filamentary mode, additional reactions are required beyond those for the glow discharge as a result of the increased electron number density and high levels of molecular dissociation. Those additional reactions include electron-impact excitation of N and O, quenching of excited N₂ by N and O, and associative ionization by collisions between excited N₂. A significant reduction in the number of species and reactions is obtained without compromising the predicted species' number densities and temperature. These results provide researchers with reduced kinetic mechanisms that high-fidelity simulations could rely on to save computational time.