A Water-Based Lossy Waveguide With High Attenuation Used in High Power Gyro-TWT

Insufficient attenuation and poor heat dissipation in the beam-wave interaction section are critical limitations in developing the megawatt-level gyrotron traveling wave tube (gyro-TWT). To solve these problems, we propose a water-based lossy waveguide with high attenuation and heat dissipation in this letter. It comprises a vacuum region, a lossless BeO ceramic, and flowing water. Measured results indicate that the proposed structure can achieve an attenuation higher than 10dB/cm at 15.5-17.0GHz. The maximum attenuation at 16.3GHz can even exceed 29dB/cm. It is sufficient to suppress oscillations at large currents. In addition, the flowing water has a higher power capacity than conventional lossy dielectric. The proposed structure paves the way for the development of megawatt gyro-TWTs.