Effects of ion-acoustic turbulence on low density charged particle beams

A computer simulation experiment to study the interaction of low density, monoenergetic charged particle beams with turbulent ion acoustic fields is described. The principal results include: (1) The basic features of the ion acoustic turbulence developed in the simulation were consistent with theoretical predictions; (2) When a beam is injected in the ion-acoustic turbulent fields, modifications in beam directed velocity and width of the particle distribution (heating) are produced. These effects are particularly marked for low energy beams, E_b/kT_e<or approximately=1 (kT_e-the thermal energy of the drifting electron population which produces the ion acoustic turbulence); (3) The stochastic heating of beam particles is determined by the properties of the turbulent fields rather than initial beam energy; (4) The changes produced in the electron beams are by far larger than those produced in proton beams of the same initial energy.