The value of swarm data for practical modeling of plasma devices

Abstract

The non-thermal plasma is a key component in gas lasers, waste gas cleaners, ozone generators, plasma igniters, flame holders, flow control in high-speed aerodynamics and other applications. The specific feature of the non-thermal plasma is its high sensitivity to variations in governing parameters (gas composition, pressure, pulse duration, E/N parameter). The reactivity of the plasma is due to the appearance of atoms and chemical radicals. For the efficient production of chemically active species high average electron energy is required, which is controlled by the balance of gain from the electric field and loss in inelastic collisions. In low-ionized plasma the electron energy distribution function is far from Maxwellian and must be found numerically for specified conditions. Numerical modeling of processes in plasma technologies requires vast databases on electron scattering cross sections to be available. The only reliable criterion for evaluations of validity of a set of cross sections for a particular species is a correct prediction of electron transport and kinetic coefficients measured in swarm experiments. This criterion is used traditionally to improve experimentally measured cross sections, as was suggested earlier by Phelps. The set of cross sections subjected to this procedure is called a self-consistent set. Nowadays, such reliable self-consistent sets are known for many species. Problems encountered in implementation of the fitting procedure and examples of its successful applications are described in the paper.

Obtaining precise electron swarm parameters from a pulsed Townsend setup

“…Measurements of electron swarm parameters in gases are required for basic studies of electron kinetics and electronatom or electron-molecule interactions [1], and are essential for simulations of plasma devices [2][3][4]. The pulsed Townsend (PT) method is a traditional experiment for measuring electron swarm parameters [1,5].…”

Calculation of Effective Molecules Collision Frequency and Cross-Sectional Ratio for Electromagnetic Discharge in Various Gases Mixtures

“…(4) against electron density-from the above result. It shows a relation between experiment and theoretical results [6]. Finally Fig.…”

“… represents the effective electron collision frequency. In an ionized gas according to the Maxwell distribution of electron velocities, the complex conductivity  is [2,4,5,6] u is the electron energy, K is the Boltzmann constant, e T is the gas temperature and  is the electron velocity. Using the…”

“…The required modification is the presence of the observed disturbing wave if the absorption of an electromagnetic wave in the region of ionosphere is determined by collision frequency of the electron in the region. According to the effect of earth's magnetic field the theory extended to transfer modulation at radio frequencies corresponding to the gyro-frequency of the electrons was predicted which has been observed experimentally [1][2][3][4][5][6][7]. In gaseous discharge plasma, controllable laboratory experiments of interaction between microwaves are simultaneously propagated.…”

Bistable solutions for the electron energy distribution function in electron swarms in xenon: a comparison between the results of first-principles particle simulations and conventional Boltzmann equation analysis

“…Most of the efforts have been devoted to electron swarms, the electron energy distribution function and the transport properties have been determined for a wide variety of gases and gas mixtures, and for a broad range of conditions, see e.g. [3][4][5][6][7][8][9][10][11][12][13]. One of the particular phenomena, the bistability of the electron energy distribution function (EEDF) is a pronounced manifestation of the nonlinear nature of these systems.…”