Experimental Evidence for Beam-Plasma Interaction in a Low-Pressure Argon Discharge

Abstract

Experimental evidence is presented that an unmodulated electron beam moving through a homogeneous plasma is unstable. A 40-mm long Ar discharge is observed by probe methods, and the densities and oscillatory properties of the plasma electrons are found. It is suggested that the beam of electrons (which comes from the cathode) becomes unstable, and excites growing longitudinal plasma oscillations, as a result of a decreasing plasma density gradient. (T.F.H.)