Fig. 1. The cavity structure and distribution of electric field relationship

Fig. 2. The normalized beam-wave coupling coefficient of the dominant and competitive modes varies with beam radius

Fig. 3. The starting current of the operating mode and the main competitive mode varies with the external magnetic field, where the beam voltage of 30 kV, beam radius of 3.3 mm and transverse-to-axial velocity ratio of 1.3 were selected

Fig. 4. The startup of multi-mode beam-wave interaction, where the beam voltage of 40 kV, beam current of 4A, transverse-to-axial velocity ratio of 1.3, beam radius of 3.3 mm

Fig. 5. The trajectory and structure of the designed MIG

Fig. 6. Overall diagram of electromagnetic wave transmission process on YOZ plane

Fig. 7. output window field distribution by Electromagnetic simulation

Fig. 8. Photo of the designed gyrotron with quasi-optical mode converter

Fig. 9. The field pattern on a piece of paper at 0.6m from the gyrotron output window

Fig. 10. Rabbit fixed on a wooden board