同轴相对论返波振荡器跨波段调频机理和实现方法研究

Frequency-tunable high-power microwave (HPM) source is one of the most important developing directions of HPM sources. Mechanical tuning method is a main approach adopted to tuning the operation frequency of HPM sources, which has already been used sucessfully in relativistic backward-wave oscillators (RBWO,which is a HPM source with high power and high efficiency, and it is suited to repetitive operation). However, the tunning method can not be easily performed and its frequency tunning range is limited to a narrow band. In view of these limitations, a novel coaxial RBWO with frequency-tuning across bands is proposed. The central features contains: (1) the operation frequency of the RBWO can jump across different bands. Through mode selection, the quasi-TEM mode in the coaxial SWS is chosen as the operation frequency (L-band), and the TM01 mode in the hollow SWS is chosen as the operation frequency (S-band); (2) the operation frequency is tunable within each band; (3) the tunning method can be easily achieved by merely altering the length of the inner conductor. The main aim of this project is to make an intensive investigation of the physics mechnism and problems of this novel device, and to fabricate one such RBWO that can work at both L- and S-bands with the online mechnical tunning governer. The project will demonstrate the feasibility of this novel technical route and be a guide to design other kind frequency-tuning HPM sources. This project plays an important role in the industrial and military fields, e.g. in electronic countermeasure and the study of microwave effects on electronics.

频率可调谐是高功率微波源的重要发展方向之一。机械调频是对高功率微波源进行频率调谐的主要手段之一，在相对论返波振荡器上得到了较为广泛的应用，但存在调谐带宽窄、调谐方式复杂等不足。本项目提出了一种新型跨波段调频同轴相对论返波振荡器的设计思想，主要特色：（1）跨波段调频，通过改变内导体长度实现模式选择与控制，使器件分别工作在同轴慢波结构的基模（准TEM 模）和空心慢波结构的基模（TM01 模）状态，实现频率在不同波段之间转换；（2）波段内频率可调，在不同波段内频率均具有一定的调节带宽；（3）调节方式简单，只改变内导体长度。本项目旨在研究跨波段调频技术涉及的物理和技术问题，研制出一台跨L、S波段在线机械调频的同轴相对论返波振荡器，实现两个波段GW级高功率微波输出。掌握跨波段调频同轴相对论返波振荡器的设计方法，并向其它波段拓展。本项目在效应研究、电子对抗等领域具有重要的应用价值。

频率可调谐是高功率微波源的重要发展方向之一。机械调频是对高功率微波源进行频率调谐的主要手段之一，在相对论返波振荡器上得到了较为广泛的应用，但存在调谐带宽窄、调谐方式复杂等不足。本项目提出了一种新型跨波段调频同轴相对论返波振荡器的设计思想，主要特色：（1）跨波段调频，通过改变内导体长度实现模式选择与控制，使器件分别工作在同轴慢波结构的基模（准TEM 模）和空心慢波结构的基模（TM01 模）状态，实现频率在不同波段之间转换；（2）波段内频率可调，在不同波段内频率均具有一定的调节带宽；（3）调节方式简单，只改变内导体长度。理论研究中，通过研究了同轴慢波器件的色散特性、模式选择等问题，提出了仅调节内导体长度实现跨波段调频的工作机理。粒子模拟中，通过抑制模式竞争、提高束-波作用效率，仅改变内导体长度，在L、S波段均获得束-波作用效率大于30%的仿真结果，对应波段内的频率调节带宽分别为8.5%和2%。实验研究中，研制出一台跨L、S 波段在线机械调频的同轴相对论返波振荡器，仅改变内导体长度，在L波段获得了功率2GW、脉宽为43ns、束-波作用效率31.4%的高功率微波输出；在S波段获得了功率1.95GW、脉宽为42ns、束-波作用效率30.6%的高功率微波输出。将该设计思想向高频段拓展，仿真实现了跨X、Ku波段调频、功率大于2GW的高功率微波输出。本项目在效应研究、电子对抗等领域具有重要的应用价值。