Plasma heating by a relativistic electron beam

Abstract

Reported are measurements on the interaction between a relativistic electron beam (REB) with the parameters 800 kV, 6 kA, 50–150 nsec, and a plasma with a density of ne=1.0×1019 m−3–1.0×1020 m−3. The electron temperature during and after the beam pulse is obtained by means of Thomson scattering. Also measured is the angular distribution of the beam electrons as a function of time and position. By varying the angular spread of the beam it is possible to pass from a kinetic to a quasihydrodynamic interaction. In both regimes measurements are compared with the appropriate theoretical model. Energy transfer is largest in the quasihydrodynamic regime and amounts to 2.5×103 J/m3 or 2.2×1016 eV/cm3. The electron temperature reaches values of 150 eV and appears limited by the electron heat conduction along the magnetic field.