Nitrogen oxide γ-band emission from primary and secondary streamers in pulsed positive corona discharge

Abstract

Nitrogen oxide γ-band emissions (A2Σ+→X2Π) from primary and secondary streamers are observed in O2∕N2 and NO∕N2 pulsed positive corona discharges with the aim of investigating the production of NO molecules and N2(A3Σu+) metastables in these primary and secondary streamers. The spatial distribution of the NO-γ emission shows that the NO-γ emission is mostly observed in the secondary streamer propagation area of the O2∕N2 discharge. That is, NO molecules are mainly produced in the secondary streamer in the O2∕N2 discharge. On the other hand, in the NO∕N2 discharge, the NO-γ emission is observed in the primary streamer propagation area. This result indicates that N2(A3Σu+) metastables are mostly produced in the primary streamer because the NO-γ emission is observed following the process NO(X2Π)+N2(A3Σu+)→NO(A2Σ+)+N2(X2Σg), where NO(X2Π) is distributed uniformly in the background gas in the NO∕N2 discharge.