Injection of a relativistic electron beam into an inhomogeneous magnetized plasma

Experiment and theory are described for a scheme of relativistic electron beam plasma heating in which increased beam energy is deposited by having the beam electrons reenter the plasma. This is done by reflecting them from a virtual cathode that they create at the plasma-vacuum boundary. In order to accomplish this, the plasma column must not be in contact with the end plate of the vacuum chamber, the injected beam current has to exceed the vacuum value, and radial losses must be suppressed by a strong longitudinal field. A one-dimensional model of beam reflection from a stable virtual cathode is proposed.