Influence of fast secondary electrons on dipole oscillations in a neutralized electron beam

It is well known that a maximal electron current in a neutralized electrom beam (NEB) is constrained by the dipole instability due to interactions between the primary electrons and the neutralizing ions. The influence of the fast secondary electrons on this instability is considered. We have examined two cases: 1) secondary electrons with full memory” (these electrons remember” the amplitude and phase of the dipole oscillations during reflections from the ends of the cooling system); 2) secondary electrons with “loss of memory”. For both cases the dependence of the NEB parameters on the concentration of the secondary electron has been investigated. Finally, we analyzed the possibility to suppress the dipole oscillations by the use of a feedback system.