Momentengleichungen für Plasmen mit anisotropem Neutralgasdruck und anisotropem Ionendruck

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Abstract
Strongly non‐Maxwellian and non‐isotropic velocity distributions of the neutral atoms and of the ions occur in collisionless plasmas at high degrees of ionization, especially in gas discharges at low pressures and high current densities and in high temperature plasmas. The velocity distributions and the related velocity moments for the neutral gas and the ion gas are calculated. The influence of the magnetic fields on the ions is neglected. Especially, the pressure tensors and the heat flow tensors are investigated. The differential equations are given for the velocity moments of the velocity distribution. Additional terms occur in the equation of motion, if the pressure is non‐isotropic and non‐Cartesian coordinates are used. A heat flow tensor is evaluated that closes the system of differential equations for the neutral gas consistently and allows to rederive typical formulas of the molecular neutral gas flow. The heat flow tensor essentially determines the type of the differential equation system for the velocity moments. It is shown, that the neutral gas temperature is not constant across the plasma. Different statements deal with the heat flow tensor in the ion gas. In particular, non‐vanishing ion temperature on the axis and a system of differential equations for the positive column under free‐fall conditions are investigated. The inertia terms for the ion gas and the neutral gas must be taken into account in the pressure balance of the plasma.