Measurement of electron distribution function in a cesium plasma

摘要

A conventional plane Langmuir probe with dc superimposed on a small sinusoidal signal is used to measure the electron‐energy distribution in a cesium discharge tube. The current‐voltage characteristics and its second‐derivative characteristics are obtained for various discharge conditions. The electron‐energy distribution at different gas‐particle densities and electric fields in the positive column are calculated. The deviation from a Maxwellian distribution is observed for a low gas density and high electric field plasma. The calculation of the distribution function is also carried out by solving numerically the Boltzmann equation with electric field, including the effects of the elastic and inelastic collisions.