Collisional damping of the high frequency instability in a beam-plasma system

Abstract

The high frequency instability resulting from the interaction of a cold electron beam with a cold plasma is investigated in the collisionless as well as collision-dominated regime. Measurements of the beam distribution function show that the instability is heavily damped at high plasma densities and exhibits a maximum at intermediate densities. The results are in good agreement with theoretical calculations with theoretical calculations invoking Coulomb collision as the main damping mechanism. Heating of the plasma by the instability can cause a drastic shift of the density of maximum instability to higher values.