A Novel High-Efficiency V-Band Coaxial Transit Time Oscillator With a Low Guiding Magnetic Field

In this article, a V-band millimeter-wave relativistic high-power microwave (HPM) transit time oscillator is investigated, which is capable of operating with high efficiency under a low guiding magnetic field. To ensure the effectiveness of microwave extraction from the electron beam’s energy, a multimode operation mechanism is adopted in the traveling wave extractor. In the meantime, to improve the modulation effect of the electron beam, a two-stage buncher is designed. Furthermore, to optimize the phase relationship between the electron beam and the axial electric field in the cavity, a resonant cavity is added between the reflector and the first buncher, thus the beam-wave interaction can be enhanced. Finally, particle-in-cell (PIC) simulation results confirm that the novel relativistic V-band coaxial transit time oscillator can output 796 MW of microwave at a voltage of 391 kV, a current of 4.87 kA, and a guiding magnetic field of 1.0 T, respectively. This corresponds to a high efficiency of 41.8%, which is a significant improvement in the efficiency of the V-band HPM sources under low magnetic fields.