Experimental and calculated N(4S) temporal density profile in the N2 flowing post-discharge

The post-discharge generated by a direct current N-2 flowing discharge was studied by optical emission spectroscopy. The experimental conditions were such that the short-lived afterglow could be detected. The post-glow emissions, first positive and 1st negative N-2 systems, were recorded along the post-discharge tube up to times of the order of 0.1 s (late afterglow). The experimental parameters, gas and N-2(X (1)Sigma(+)(g)) vibrational temperatures, were measured and utilized in a numerical kinetic model developed for calculations of the N(S-4) absolute density along the post-discharge. Moreover, the model was employed in estimations of the percentage of each excitation channel to the excitation of the N-2(B-3 Pi (g), v = 11) state as a function of post-discharge time. Among them, the main excitation channels are the N(S-4) three-body recombination and the N-2(A E-3(u)+) pooling with the U N-2(X E-1(g)+, v) states. From the computation of the percentage of contribution of the three-body recombination mechanism in the overall excitation of the N-2(B (3)Pi(g), v = 11) state, the first positive emission intensity at 580.4 nm wavelength was corrected. After correction, one expects that the emission intensity would be proportional to the square root of the N(S-4) density. Therefore, [N(S-4)] experimental estimations can be achieved as a function of post-discharge position or post-discharge time. The experimental profiles are in good agreement with our previous theoretical results and the spatial parametrization to the 580.4 nm band provides a significant advance to the experimental method developed by Bockel et al.