Geschwindigkeitsverteilung, Teilchendichte, transversale Driftgeschwindigkeit und Energiedichte des Neutralgases in der Freifallsäule unter Berücksichtigung der „Neutralgasaufzehrung”︁ durch die Ionisationsvorgänge

Abstract

AbstractA neutral gas rarefaction caused by ionization processes occurs in the plasma of the low pressure gas discharges. The velocity distributions, the particle density, the transversal drift velocity and the energy density of the neutral gas are calculated both for the plane and for the cylindrical positive column under free fall conditions. The neutral gas rarefaction is taken into account.It is shown, that the velocity distributions is non‐Maxwellian and anisotropic. The pressure tensor is anisotropic, too. Particle density and energy density of neutral gas decrease with increasing electron density and electron temperature relatively homogeneously over the cross section of the column. Only, if the degree of ionization is high, these densities are much smaller near the axis than at the wall. Decreasing neutral gas temperature causes a similar change in the particle density profile as increasing electron density and electron temperature do. The transverse neutral gas pressure decreases from the axis to the wall in all cases. In the steady‐state column an upper limit exists for the transverse particle current density of the neutral gas and of the ion gas. This limit depends on the gas temperature, the filling pressure and the atomic mass of the filling gas.In the appendix the Boltzmann equation is given in a form, which is suitable to investigate cylindrical problems not only for simple examples.