Comparative Simulation of Ionization Wave Dynamics in Ne and Ar within Continuous Medium Equations

摘要

A numerical one-dimensional simulation of the dynamics of an ionization wave of negative polarity in Ne and Ar under the action of an applied electrostatic field in the local energy approximation of the model of a continuous medium, as applied to the development of streamers in gases, is carried out. To this end, the model equations are presented in a dimensionless form, and approximations by analytical functions of the impact ionization coefficient of gases, mobility and diffusion of electrons are derived on the basis of experimental data and theoretical calculations in a wide range of reduced field strengths up to 10(-4)-5 x 10(4) Td. Numerical solutions of the equations for the electron density behind the front, the velocity of its motion and thickness in the field strengths of 50-4 x 10(3) Td are obtained. Two dimensionless parameters are estimated, which are the ratio of the electron relaxation rates in the gas to the rate of changes induced by the external field. A necessary condition that limits the application of the model under consideration to estimates of the dynamics of the ionization wave of a gas is the requirement that both parameters significantly exceed unity. The parameters decrease with an increase in the reduced field strength and, in particular, are equal to 10 at the value of the latter of approximate to 1180 Td.