Transport of self-focused relativistic electron beams

Experiments with the Astron beam (5 MeV, 0.4 kA) and an FX-25 beam (1.5 MeV, 15 kA) show that the transport of self-focused electron beams in neutral gases is limited by two instabilities. At gas pressures from nearly zero to a few torr, the propagation is dominated by a form of two-stream instability. At higher pressures the resistive hose instability dominates. Between the two regimes, a pressure window exists in which the higher current diode beam propagates stably in both conducting and insulating drift tubes.