Effect of background electron plasma waves on ion-beam neutralization

The mechanism for the deneutralization of a positive ion beam during the excitation of plasma waves in a neutralizing electron background is studied. The deneutralization of extended fast beams which are not too dense is governed by not only the electron heating through Coulomb collisions with beam ions but also the longitudinal acceleration of electrons by the fields of the electron waves excited by the beam. Experimental data which have been obtained on the constant and varying beam potentials during a nonlinear ion-electron interaction are consistent with calculations based on the trapping of electrons by wave fields