Ionization of N2 in radio-frequent electric field

Abstract

Rate coefficients for the electron impact ionization of the N2 molecule are calculated in non-equilibrium conditions in the presence of time-dependent electric field. A Monte Carlo simulation has been developed in order to determine non-equilibrium electron energy distribution functions within one period of the radio-frequent (RF) electric field. By using these distribution functions, rate coefficients for ionization of the N2 molecule have been obtained time resolved within one period in the frequency range from 13.56 up to 500 MHz, at effective reduced electric field values up to 700 Td. This work presents an insight into the temporal characteristics of ionizing process and provides the ionization rate coefficients that can be of great use for correct implementation in modeling RF plasma discharges. A behavior of rate coefficients under the influence of magnitude and frequency of the fields was studied separately revealing some interesting features in time dependence.

Dissociation of N2 by electron impact in electric and magnetic RF fields

“…This delay is also a consequence of the inertia of the electrons' motion through the N2 gas and is more pronounced at higher frequencies. 14 Regarding the influence of the strength of the electric and magnetic fields on the appearance of the rate coefficients, they are also noticeable in Fig. 2.…”

“…In order to simulate the electrons' motion through the N2 gas under the presence of timevarying electric and magnetic fields, the Monte Carlo (MC) code that has been used in earlier works of our group, 14,15 is modified and used. 16 The motion of electron is described by the following differential equation:…”

“…In our previous works we presented these comparisons for drift velocity, longitudinal diffusion coefficient and ionization coefficient, where excellent agreements were obtained. 14,42 Comparison was also made with the Boltzmann equation-based software BOLSIG+ (version 1.1). 43 By including the present cross section database in both our Monte Carlo simulation and BOLSIG+ oscillating field routine, we obtained the agreement of period averaged mean electron energy within 2 % only.…”