Experiments on a gyrotron backward-wave oscillator with an intense relativistic electron beam

We report experimental results of X-band microwave generation with an intense relativistic electron beam (450 keV, 300 A, 10 ns) injected into a rectangular waveguide immersed in a uniform axial magnetic field (4–10 kG). The frequency range and tunability of the radiated microwave show good agreement with the theoretical model for a gyrotron backward-wave oscillator. The power of radiated microwaves increases not only as the beam current increases (100–350 A ) but also as the interaction length increases (30–100 cm). Its maximum value is estimated to be about 1 MW.