PREDICTED ELECTRON-TRANSPORT COEFFICIENTS AT HIGH E-N-VALUES .2. NITROGEN

Transport coefficients of electrons in nitrogen are calculated over the range 10-16≤E/N≤7.3×10-15 V cm2 by solving the Boltzmann equation using the classical two-term expansion in spherical harmonics. However, as in the case of H2 treated in a previous paper, the sources of new electrons produced by ionization has been accounted for in the Boltzmann equation. It is shown that the release of these new electrons has an effect on the distribution function starting from E/N≃2×10-15 V cm2, which increases rapidly as E/N increases. The recently available cross sections for the excitation of the electronic states of N2 have been used along with the total-momentum-transfer cross section derived by Cartwright. The predicted values of the ionization coefficient are in very good agreement with the experimentally measured values except at low E/N values, for which our predicted ionization coefficients are slightly less than the experimental ones. The agreement is also good for the drift velocities over the entire E/N range, while for the characteristic energies the agreement becomes less satisfactory for E/N≳2.5×10-15 V cm2. The electron excitation rates for the first eight vibrational levels, the A 3Σ +u, B 3Πg, W 3Δ u, and C 3Πu electronic states are presented as a function of E/N. The ionization rate and the total dissociation rate (including the dissociative ionization process) are also given as a function of E/N. The percentage of the input power which is delivered to the elastic and the various inelastic processes are presented as a function of E/N.