Fig. 1. Design model and components of the 105/140 GHz MW gyrotron

Fig. 2. Photographs of the 105/140 GHz MW gyrotron and experimental setup

Fig. 3. Thermal paper’s burned patterns of RF beams at the window aperture at 105 GHz and at 140 GHz obtained by a 5 ms short pulse

Fig. 4. Pulse test waveforms of output with the 140 GHz/1 MW continuous short-pulse operation

Fig. 5. Results of pulse extension test of output with 105 GHz /400 kW/1 s

Fig. 6. Results of pulse extension test of output with 105 GHz /300 kW/2 s

Fig. 7. Infrared images at the highest temperature of windows during pulse extension tests

Fig. 8. Spectrum of mixing signal of RF beam during a 105 GHz/300 kW/2 s long-pulse operation