Theoretical analysis and experimental verification of electron beam transmission with low guiding magnetic field in V-band coaxial transit-time oscillator

The transmission of an electron beam with a low magnetic field is theoretically and experimentally investigated. In a high frequency band, due to a narrow tunnel of the electron beam, the transmission of the electron beam highly depends on beam parameters. The transmission of the electron beam is analyzed through the beam envelope equation, and accordingly, the relationship between beam parameters and transversal diffusion of the electron beam is derived. By particle-in-cell simulation, the influence of the current density, loading position, and guiding magnetic field on the electron beam is discussed. An electron beam with a beam voltage of 400 kV and a beam current of 5.0 kA in the guiding magnetic field of 1.0 T is applied in the experiment. The experiment consists of the electron beam bombardment on the nylon target and measurements of the beam current. The experimental results show that the electron beam can be stably and uniformly transmitted at a low loss under the given conditions.