Electron swarm behavior in nonuniform fields in nitrogen

The transport of electrons through a background nitrogen gas under the influence of a spatially varying electric field is studied through a Monte Carlo simulation. Nonhydrodynamic effects, i.e., a nonlocal dependence of the electron transport and rate coefficients on the ratio of the field strength to the neutral density, E/N, are observed. For example, the high-energy tail of the electron-energy distribution function is sluggish in responding to the spatially varying field, and hence the ionization coefficient lags the local field value. In addition, the spatially dependent vibrational-excitation-rate coefficient goes well beyond the range of values found in hydrodynamic calculations. The results are discussed in terms of recent formulations of nonhydrodynamic transport theory and are contrasted with previous results.