The neutralization by ions and a type of oscillations of the electron beam

The neutralization factor is deduced for a partially offset electron beam in a longitudinal magnetic field. The neutralization factor depends on macroscopic quantities and can be computed for the given configuration. It is used in the dispersion relation, and the frequency of self-excited oscillations of the two-stream instability of a rotating non-neutral electron-ion beam is found. The frequency modulates the electron beam current. The existence of such oscillations is proved experimentally. The experimental technique used is described. (author)