Investigation of the Effect of Dielectric Dissipation for a High Power W-band Gyro-TWT

The dielectric-loaded gyro-traveling wave tube (DL gyro-TWT) can achieve high output power in the millimeter-wave and terahertz frequency bands. When the gyro-TWT is operated at high average power, the temperature of the dielectric material increases significantly due to the large absorption of electromagnetic waves, which can lead to oscillations and severe outgassing. Therefore, quantitatively studying the thermal performance of ceramics is essential to ensure that the gyro-TWT operates stably. In this paper, The dependence of the dielectric material permittivity and its attenuation properties on temperature are measured at W-band. Then, the temperature distribution of a W-band gyro-TWT developed by the University Electronic Science and Technology of China (UESTC) is quantitatively investigated by an iterative approach. Simulated results indicates that temperature of the gyro-TWT is different when it operates at different frequencies. The dielectric temperature can reaches 240°C with a pulse duration of 0.2 ms and a duty cycle of 2% for 90 GHz. This work provides an important guidance in determining proper operating parameters and improving the gyro-TWT stability.