Interaction of a rotating relativistic electron beam with plasma

Results of an experimental study of the interaction of a rotating relativistic electron beam with plasma confined in a mirror field are presented. The rotating relativistic electron beam has been propagated up to a distance of 150 cm in a metal tube containing plasma. Net axial and azimuthal currents are observed. The azimuthal currents last for periods much longer than the beam duration and the axial currents. The present experimental studies indicate that the azimuthal return current diamagnetism contributes substantially to the diamagnetic loop signal. Observational evidence is presented for the generation of a trapped azimuthal return current layer in the magnetic mirror and it is shown that mirror field plays an important role in the formation of the trapped return current layer. Experimentally observed response of the plasma to the rotating relativistic electron beam is in general agreement with numerical results, obtained using a magnetic diffusion model.