High power millimeter waves generated by an overmoded relativistic Cherenkov-type oscillator

An overmoded relativistic Cherenkov-type high power millimeter wave generator operating in Ka-band has been investigated. The associated particle-in-cell (PIC) simulation and experimental results are presented in this paper. The relativistic electron beam with a peak current of 9.9 kA was generated by a pulsed power accelerator launched at a voltage of 605 kV. The relativistic electron beam was guided by an axial magnetic field of about 1 T and transported through the overmoded slow-wave structure. Typically in experiments, the millimeter wave power radiated in the far field was about 630 MW with a frequency of 32.1 GHz and a pulse width of about 10 ns. The radiation mode was well controlled to be quasi-TM₀₁ mode.