High-Power Multifrequency Radiation Source Based on Gyro-TWT With External Coupling Feedback

In this article, we propose and measure a high-power Ku-band gyrotron traveling wave tube (gyro-TWT) with external coupling feedback to generate wide-band multifrequency signals. With varying the beam current, pitch factor, coupling coefficient, and feedback loop length, strong oscillations from single-frequency to multifrequency regimes of the self-excitation TE <tex-math notation="LaTeX">₁₁</tex-math> mode are observed in the zero-driven state. Particle-in-cell (PIC) simulation shows the gyro-TWT can achieve a maximum output power of 192.86 kW and 56.67 MHz interval between main spectral components in the range of 14.85–17.46 GHz. It was confirmed by a proof-of-principle experiment based on a Ku-band gyro-TWT with an external feedback loop, which yielded 2.6 GHz multifrequency signals with an interval of 54 MHz and maximum output power of 174.25 kW at a duty cycle of 1%. The generated multifrequency radiation signals may have potential applications in microwave wireless communication, jamming of radar systems, and microwave frequency combs.