Transport Properties of Charged Particles in Gases
The motion of charged particles such as electrons and ions under action of external electric field determines conductivity and dielectric permittivity of ionized gases. Such features are important for calculations of the absorption coefficient of electromagnetic waves in the gases, the rate of electron energy increasing, etc. The transport coefficients of the electrons in gases such as electron mobility, transversal and longitudinal diffusion coefficients and mean energy of electrons are functions of the applied field strength and the gas pressure. The discrepancy with linear pressure dependence of the transport coefficients is observed for pressures above 10 atm. The electron transport coefficients are functions of the gas temperature for low field strengths and become the field dependent for high fields. The electron transport coefficients are calculated by Kintech Lab for a wide range of the thermodynamic parameters of a gas (pressure and temperature) and applied electric field strengths. Elastic and inelastic collisions of electrons with atoms and molecules are taken into account. Calculations can be carried out both for one component gases (atomic or molecular) and for mixtures of different gases.
Diffusion and mobility of an ion are important parameters which determine the motion of the ion through the gas. These parameters are functions of the gas temperature and they are related to each other by Einstein formula. The ion transport coefficients are determined by collision processes between the ion and atoms and molecules of the gas. The polarization interaction between charged and neutral particles is the general interaction whic determines the ion transport coefficients. If the ion moves in foreign gas, the elastic collisions governed by the polarization interaction are taken into account by the Langevin theory. Polarization capture and small-angle scattering are principal processes in the theory. If the ion moves in own gas, the charge exchange of atom on the ion have to be taken into account. The difference between electron and ion mobility leads to the charge separation and creation of a space charge in an ionized gases. The space charge electric field influences the motion of the charges with different mobility and leads to their bipolar diffusion. The coefficient of the bipolar diffusion depends on as both electron and ion mobility and the mean energy of electrons. The bipolar diffusion coefficients are calculated by Kintech Lab for a wide range of the thermodynamic parameters of a gas (pressure and temperature) and applied electric field strengths.
- Transport properties of electrons
- Transport properties of ions
Examples:
Calculation of electron transport coefficients in Xenon, Methane and their mixtures
Calculation of cathode layer creation in Ar gas
