Experiment and Power Capacity Investigation for a Ku-Band Continuous-Wave Gyro-TWT

In this article, the design and experiment of a high continuous-wave (CW) power Ku-band gyrotron traveling-wave tube (gyro-TWT) are described. The hot experiment results indicate that the TE11 mode gyro-TWT, driven by a 50 kV-4.5 A electron beam, can produce a maximum CW output power of 49 kW, with an efficiency of 21.8% at 16 GHz. The saturated bandwidth is 2 GHz, and more than 30-kW CW output power is achieved from 15 to 17 GHz. However, the outgassing is observed in the low-frequency range, which limits the enhancement of CW output power. Then, the simulation is performed and indicates that the attenuated power distribution and heat dissipation on the dielectric-loaded circuit (DLC) are dependent on the frequency, attenuation of lossy ceramic, and input power. Also, the maximum temperature of lossy ceramic at 15 and 15.5 GHz is too high for stable operation. A nonuniform DLC is utilized to dissipate power dispersedly. The simulation results show that the maximum power loss on a single lossy ceramic is reduced by 77.9% and 48.9% at 15 and 15.5 GHz, respectively. It indicates that the nonuniform DLC could adjust the dissipation power on the lossy ceramics via the attenuation profile varying with frequency and effectively enhance the power capacity of dielectric-loaded gyro-TWT.