Kinetics of Atomic and Metastable Species in N₂ and H₂-N₂ Ns Pulse Discharges

Time-resolved, absolute number densities of metastable N₂(A³Σ_u⁺,v=0,1) molecules, ground state N and H atoms, and rotational-translational temperature are measured by TDLAS and TALIF in nitrogen and N₂-H₂ plasmas during and after a ns pulse discharge burst. Both N₂(A³Σ_u⁺,v) populations and the rate of N atom generation decrease significantly during the ns pulse discharge burst. Comparison of the measurement results and the modeling predictions indicates an additional major channel of N₂ dissociation in the plasma, by energy pooling in collisions of two N₂(A³Σ_u⁺) molecules. Additional measurements in a 1% H₂-N₂ mixture demonstrate a further significant reduction of N₂(A³Σ_u⁺,v) populations due to the rapid quenching by H atoms, which also diminishes the contribution of N₂(A³Σ_u⁺,v) dissociation, such that the N atom number density decreases significantly. On the other hand, the rate of H atom generation, produced predominantly by the dissociative quenching of the excited electronic states of nitrogen by H₂, remains about the same during the burst. The present quantitative results will be used for the further analysis of plasma-assisted catalysis generation of ammonia.