On non-hydrodynamic properties of the electron gas in the plasma of a DC discharge

The linearized one-dimensional Boltzmann equation was solved for the electron gas in the positive column of a low-current DC-discharge. A sinusoidal perturbation of the electric field was assumed in the column and the perturbed distribution function was found. The problem was solved both numerically and approximately. It is shown that in the absence of an electron-electron interaction strong deviations from the solution of the hydrodynamic quasihomogeneous equations appear for certain wavelengths, which were called resonant. These wavelengths almost exactly agree with the characteristic wavelengths of the ionization waves of the s- and p-variety. A physical interpretation of this resonant behaviour is given and its connection with the long correlation length in a plasma with non-interacting electons is pointed out.Na Slovance 2, Praha 8, Czechoslovakia.