Dependence of macro-kinetic paraments on the local electric field and mean energy in Nitrogen*

The fluid models are frequently used to describe a non-thermal plasma such as a streamer discharge. The required electron transport data and rate coefficients for the fluid model are parametrized using the local-mean-energy approximation (LMEA) and the local field approximation (LFA). We performed Monte Carlo simulations in Nitrogen gas with step changes in the E/N (reduced electric field) to study the behavior of the transport properties in the transient phase. Our results show that rates equilibrate faster for step ups compared to step downs of the same amount. Also, the mean electron energy takes a considerably longer time to reach steady-state values compared to transport rates. During the transient phase of the simulation, we extract the mean energy and the corresponding transport parameters and rate coefficients. Our results show that for a given mean energy the electron drift has a significant spread and depends on the transient path. However, the high energy threshold rates such as ionization have a low spread. The use of electron mean energy to parametrize electron drift would lead to erroneous results.In either approach (LMEA or LFA), E/N would be a better parameter for electron drift.