Two dimensional collapse of Langmuir waves in electron beam-plasmas

Abstract

Interactions between an electron beam and argon plasma, in the presence of a strong axial magnetic field, have resulted in the formation of standing Langmuir waves together with spatially localized ion density depletions of up to 40%. On typical ion motion time scales, the standing waves collapse to axial and radial dimensions of approximately 20 lambda D and a few thermal electron Larmor radii respectively. Both accelerated and decelerated components of the electron beam have been observed to couple with the plasma generating additional features in the wave spectrum.