Optimizing and experimental investigation of a Ka-band relativistic backward wave oscillator operating at TM 02 mode

A Ka-band relativistic backward wave oscillator (RBWO) operating at TMo2 mode was designed in our previous work. The RBWO has larger size, higher power capability and is suitable for operating at lower guiding magnetic field. The post and front cascaded resonators of the RBWO was optimized for compactness and stability of the system, as well the selection of TMo2 mode. The optimized RBWO preformed the same power level as the former structure by the particle in cell (PIC) simulation. We got 363 MW output power with frequency of 29.3 GHz at guiding magnetic field of 1 T in the experiment. The operating frequency, radiation pattern and the regulation of output power versus diode voltage were all corresponding with the PIC simulation. The RBWO was operating as we expected.