Turbulent heating in a moderate energy electron beam plasma experiment

The excitation and dissipation of electron beam driven electrostatic turbulence has been investigated experimentally and theoretically. Optimization of the beam to wave power transfer efficiency is shown to depend on the details of the linear dispersion of plasma waves on the bounded plasma column. In addition, the time variation of the cw operated beam plasma system has been modeled by a coupled set of nonlinear rate equations for the intensity of unstable field fluctuations, the electron temperature, and the plasma density. Agreement with the experiment is excellent allowing identification of the important dynamics. In particular, the dominant dissipation mechanism is shown to be stochastic heating of (nonresonant) thermal electrons.