Vibration-to-translation energy transfer in atmospheric-pressure streamer discharge in dry and humid air

Vibration-to-translation (V–T) energy transfer in atmospheric-pressure streamer discharge is numerically simulated using a two-dimensional electro-hydrodynamic model. The model includes state-to-state vibrational kinetics in humid air and is coupled with the compressible flow equation of the gas fluid. The vibrational distribution of ${\text{O}}_2\left(v\right)$ reaches equilibrium more quickly than that of ${\text{N}}_2\left(v\right)$, whereas the energy released from ${\text{O}}_2\left(v\right)$ does not increase the gas temperature. In humid air, the decay rate of the vibrational energy of ${\text{N}}_2\left(v\right)$ is accelerated by the V–T energy transfer through water molecules and the energy heats the gas. However, the increase in gas temperature due to V–T energy transfer is not always seen because it competes with thermal diffusion. (paper)