Injection of a relativistic electron beam into a plasma

It is shown experimentally that a relativistic beam (W = 400 kEv, I = 600 A, T = 30 nsec) induces in the plasma an inverse current that compensates for the beam current. The degree to which the beam current is compensated for is plotted against the plasma density. An effect of inverse-current breakdown is observed which is probably associated with the constraints placed on the emission at the metal/plasma interface. In the case where the plasma density is insufficient for complete compensation of the beam current, and the beam and plasma axes do not coincide, a rotation of the beam about the plasma axis was observed.