High-current oversized annular electron beam formation for high-power microwave research

The authors report the study of a high-current accelerator, capable of producing thin (2mm) annular, mildly relativistic (450keV) electron beams (up to 1.5kA) of diameter of 70mm. Propagation of an electron beam through a 2m long, coaxial beam channel, with inner and outer conductor radii of 30 and 40mm, respectively, was demonstrated with the electron beam current at the beam-channel output measured using a Rogowski coil. The results obtained are compared with those predicted via numerical simulation. The electron beam obtained was used for proof-of-concept work demonstrating the operation of a high-power maser operating at millimeter wavelengths, using two-dimensional distributed feedback.