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

In this article, the design and power capacityinvestigation 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 pro-vides 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 mechanicalstrength. Simulation results indicate that the Q-band TE01mode gyro-TWT, driven by a 55 kV-9.1 A electron beam(3.2% transverse velocity spread), can produce a maximum out put power of 145 kW, with a gain of 74 dB and a noverall 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(degrees)C, 241(degrees)C, and134(degrees)C, respectively. The simulation results demonstrate the feasibility of the gyro-TWT for more than 100 kW CW stabilized operation.