NUMERICAL SIMULATION OF UNSTEADY COLD PLASMA STREAMS OF DIELECTRIC BARRIER DISCHARGE IN AIR

Abstract

A new mathematical model of a low-temperature non-equilibrium ideal plasma of a dielectric barrier discharge in air is developed. The drift-diffusion approach is chosen as the base for describing the spatial-temporal structure, including unsteady electrodynamics processes, kinetic phenomena, and plasma-chemical reactions. The model takes into account electronically excited and metastable states of nitrogen and oxygen molecules, oxygen atoms, electrons, as well as positive and negative ions, a total of 14 particles and 97 plasmachemical reactions, including surface processes. Chemical reactions include the processes of dissociation, ionization of molecules by electron impact from the ground state, stepwise and associative ionization, photoionization, excitation of molecules, ionization of excited (metastable) molecules, electron attachment and detachment, recombination of electrons and positive ions, chemical transformations of neutral atoms, molecules and ions, as well as processes of secondary electron emission from an open electrode and a dielectric surface. For unsteady equations of plasma dynamics, an implicit numerical algorithm with pseudotime iteration is developed, which is based on a finite-volume approach. In unsteady equations for the density of plasma particles, the drift derivatives were approximated using the TVD scheme with the MinMod limit function. A single implicit numerical algorithm for the efficient solution of a nonuniform system of initial equations is implemented. A series of computational experiments are conducted to simulate the unsteady processes of a lowtemperature nonequilibrium plasma of a dielectric barrier discharge. A detailed study of the stages of formation, development, and quenching of a cathode-directed streamer for real configurations of plasma actuators based on the developed mathematical model has been carried out. The unsteady plasma characteristics in the region above the dielectric surface are analyzed, including the distribution of particle density, electric potential, and components of the Lorentz force.