Generation, propagation, and application of rotating relativ1stic electron beams in the absence of an external guide field

Rotating relativistic electron beams have been the subject of a number of experimental and theoretical studies, principally concerned with the use of such beams for heating plasmas. The rotating beams are usually created by passing a hollow cylindrical beam through a nonadiabatic magnetic cusp, and are propagated down an axial guide field into either plasma or neutral gas. It has recently been demonstrated that an intense rotating relativistic electron beam can propagate in the absence of an external guide field inside a metal tube filled with neutral hydrogen gas.The radial equilibrium of the beam is determined by the axial and azimuthal fields of the beam and the induced wall currents. Because the tube is initially field-free, the total net flux must always be zero, and the axial fields inside, B_zi and outside, B_zo ,the beam are in opposite directions. In addition the axial component of the beam current produces an azimuthal field, B_θ. This produces a reversed field configuration with both B_θ and B_z fields. This paper presents a summary of recent experiments on the generation and propagation of rotating beams and their application for collective acceleration of protons and the generation of field reversed configurations for plasma confinement.