Abstract
A slightly ionized, spatially homogenous gas is subjected to a weak constant electric field, and the relaxation of an arbitrary velocity distribution function for the electrons is studied. When the cross section for electron-molecule collisions decreases faster than 1/v2 for large velocities there exists no stationary solution of the Boltzmann equation. The runaway rate for different collision cross sections is calculated. As a further application the runaway rate for electrons in n-InSb at helium temperatures is estimated.