Design and Power Capacity Investigation of a Q-Band 100-kW-Continuous-Wave Gyro-TWT

In this article, the design and power capacity investigation of the gyrotron traveling wave tube (gyro-TWT) with more than 100 kW continuous-wave (CW) in
${Q}$
-band are described. An input coupler is designed with a photonic bandgap isolator to ensure a wide bandwidth and low microwave leakage. A nonuniform dielectric-loaded circuit (DLC) is proposed to address the severe microwave loss in lossy ceramics at high power levels. The curved depressed collector with a multigap output isolator provides an effective approach to further enhance the overall efficiency and power capacity of high-frequency gyro-TWTs. An output window, equipped with boundary heat transfer channels, is employed to improve mechanical strength. Simulation results indicate that the
${Q}$
-band TE01 mode gyro-TWT, driven by a 55 kV–9.1 A electron beam (3.2% transverse velocity spread), can produce a maximum output power of 145 kW, with a gain of 74 dB and an overall efficiency of 40% at 48.5 GHz. The power output exceeding 100 kW is achieved in the 47–50 GHz range, with an overall efficiency of over 30%. With the efficient thermal management system, the maximum temperature on the DLC, collector, and output window are 190 °C, 241 °C, and 134 °C, respectively. The simulation results demonstrate the feasibility of the gyro-TWT for more than 100 kW CW stabilized operation.