De-Excitation of Excited States in a Nitrogen Switch After Discharge

Abstract

The de-excitation of nitrogen excited states after spark gap discharge was investigated with time-resolved optical emission spectroscopy method. Recombination of ionized particles was experimentally proved less than several tens microseconds. After the recombination process, it was shown that atomic nitrogen in ground state [N(4S)] and molecular nitrogen in first excited state [N2( $\text{A}^{3} {\Sigma }_{u}^{+}$ )] was long-lived particles (metastable state) after gas discharge. Characteristics of decay for N(4S) and [N2( $\text{A}^{3} {\Sigma }_{u}^{+}$ )] were studied, and their lifetime and decay of density were estimated in this paper. Peculiar unexponential decay of N2( $\text{A}^{3} {\Sigma }_{u}^{+}$ ) showed there was reproduction process of N2( $\text{A}^{3} {\Sigma }_{u}^{+}$ ) after gas discharge. N(4S) could be the source for reproduction process under their mechanism of three-body recombination. Low ionization energy and high ionization collision cross section of N2( $\text{A}^{3} {\Sigma }_{u}^{+}$ ) make it a possible factor limiting the switch recovery. The de-excitation of metastable states opens novel perspectives for understanding the recovery of gas switch.