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

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(
⁴
S)] and molecular nitrogen in first excited state [N
₂
(
$\text{A}^{3} {\Sigma }_{u}^{+}$
)] was long-lived particles (metastable state) after gas discharge. Characteristics of decay for N(
⁴
S) and [N
₂
(
$\text{A}^{3} {\Sigma }_{u}^{+}$
)] were studied, and their lifetime and decay of density were estimated in this paper. Peculiar unexponential decay of N
₂
(
$\text{A}^{3} {\Sigma }_{u}^{+}$
) showed there was reproduction process of N
₂
(
$\text{A}^{3} {\Sigma }_{u}^{+}$
) after gas discharge. N(
⁴
S) could be the source for reproduction process under their mechanism of three-body recombination. Low ionization energy and high ionization collision cross section of N
₂
(
$\text{A}^{3} {\Sigma }_{u}^{+}$
) 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.