Ku波段高功率高增益径向相对论速调管放大器研究

Spatial coherent combination (SSC) of high power microwave (HPM) is capable of significantly improving the equivalent radiation power of HPM system, which makes it one of the most important development directions in HPM field. Relativistic klystron amplifier (RKA), owing to its special merits of high power, stable frequency and controllable phase, is one of the preferred devices for SSC of HPM. However, limited by the power handling capacity at high-frequency band, RKA of generating gigawatt-level power at Ku-band has not yet been reported currently. But the Ku-band HPM has wide application prospect in Civil technology and military domain. For this purpose, a Ku-band RKA with features of high power, high gain, high efficiency, long pulse and low magnetic field is developed and investigated in this research program. With a combined method of theoretical modeling, simulation and experimental research, this program focuses on investigating and solving the related scientific problems of generation and stable propagation of the radial intense electron beam under the condition of low magnetic field, deeply bunching of the radial electron beam, the method of mode isolation and the suppression of the self-oscillation in radial high-frequency structure, accurately controlling of the phase of generated microwaves. A microwave will be achieved with peak power of about 1 GW, gain of above 50 dB, phase jitter of less than 15 degrees, pulse width of hundreds of nanoseconds, demonstrating the feasibility of this research program. Besides, the physical mechanisms and design methods of this Ku-band RKA will be mastered. Moreover, this work will lay the foundation of the SSC of Ku-band HPM in future, and provide the theoretical references for the research of higher frequency-band high power RKAs at the same time.

高功率微波（HPM）空间相干合成能够大幅提升系统的等效辐射功率，是HPM领域的重要发展方向之一，相对论速调管放大器兼具高功率、频率稳定、相位可控等优点，是空间相干合成的优选器件之一。然而，受功率容量限制，目前尚未见相对论速调管放大器在Ku波段产生GW级微波的报道，而Ku波段HPM在民用科技与军事领域应用前景广泛。为此，本项目提出开展Ku波段高功率、高增益、高效率、长脉冲、低磁场径向相对论速调管放大器研究，通过理论分析、仿真模拟与实验验证相结合的方法，研究并解决低磁场径向强流电子束的产生与传输、径向电子束的深度群聚、径向高频结构模式隔离与自激振荡抑制、输出微波相位精确控制等科学难题，实现峰值功率约1 GW，增益大于50 dB，相位抖动小于15°的百纳秒级微波输出，掌握器件物理机制与设计方法，为开展Ku波段HPM空间相干合成奠定基础，同时也为发展更高频段的高功率相对论速调管放大器提供技术参考。

空间相干功率合成将多个高功率微波（High Power Microwave, HPM）器件产生的微波进行相干合成，可大幅提升系统等效辐射功率，已经成为HPM领域发展的重要方向之一。相对论速调管放大器（Relativistic Klystron Amplifier, RKA）的输出微波频率与相位受控于外部种子源注入信号，具备锁频锁相的潜力，是相干功率合成的优选器件之一。本项目瞄准高功率微波领域空间相干合成的发展方向，针对RKA向Ku等更高频段拓展面临的技术瓶颈，提出了Ku波段径向RKA的技术方案，典型实验结果表明，器件能够在Ku波段实现功率为1.1 GW、增益为50.9 dB、效率为35 %、脉宽为82 ns、抖动平均值约为14.6度的高功率微波输出，论证Ku波段径向RKA技术方案的可行性，器件的引导磁场强度控制为0.4 T，注入射频功率降低至9 kW，完成项目预期的研究目标。本项目研究目标的完成，能够为开展Ku波段HPM空间相干合成奠定基础，为RKA向更高频段发展提供一定的技术参考。