Interaction of an intense relativistic electron beam with a plasma-filled waveguide in a magnetic field

Analytic computations and PIC code simulations for the interaction of an intense relativistic electron beam and a plasma are presented. In their simulations, a fast rise time (-- 5 ns) 10 kA REB (1 MeV) is injected into a plasma-filled waveguide immersed in an axial magnetic field. Beam transport and microwave generation by beam-plasma instabilities are investigated in both the infinite and finite B field cases. In the finite B field case, both the two-stream and cyclotron instabilities are important. Calculations of charge and current neutralization of the REB are performed in the intense beam regime. These calculations provide the appropriate parameters for the linear dispersion relation to the system. This dispersion relation is solved to determine the nature of the instabilities; i.e., their microwave spectra and growth rates