Fast gas heating in nitrogen-oxygen discharge plasma: II. Energy exchange in the afterglow of a volume nanosecond discharge at moderate pressures

The process of fast gas heating in air in the near afterglow of a pulsed nanosecond spatially uniform discharge has been investigated experimentally and numerically at moderate (3-9 mbar) pressures and high (200-400 Td) reduced electric fields. The temporal behaviour of discharge current, deposited energy, electric field and temperature was measured. The role of processes with participation of excited and charged species was analysed. It was shown that under the considered conditions the main energy release takes place in reactions of nitrogen and oxygen dissociation by electron impact and quenching of electronically excited nitrogen molecules, such as N(2)(A(3)Sigma(+)(u), B (3)Pi(g), C (3)Pi(u), a' (1)Sigma(u)) by oxygen and quenching of excited O((1)D) atoms by N(2). It was shown that about 24% of the discharge energy goes to fast gas heating during the first tens of microseconds after the discharge.