0.5 THz返波管电子光学系统设计

1)中国科学院高功率微波源与技术重点实验室,北京100190; 2)中国科学院大学,北京100190

太赫兹; 电子光学系统; 束流通过率; 电子枪; 阴极; 永磁聚焦系统

Design of electron optics system for 0.5 THz backward wave oscillator
ZHAO Chao1, 2, LIU Wenxin1, 2, WANG Yong1, 2, GUO Xin1, and WANG Meng1

1)Key Laboratory of High Power Microwave Sources and Technologies, Chinese Academy of Sciences, Beijing 100190, P.R.China2)University of Chinese Academy of Sciences, Beijing 100190, P.R.China

terahertz; electron optics system; passing rate of electron beam; electron gun; cathode; permanent magnetic focusing system

DOI: 10.3724/SP.J.1249.2019.02135


电子光学系统是真空电子器件的重要组成部分,主要包括电子枪、聚焦系统和收集极.电子光学系统的电子注聚焦和传输特性对器件性能指标至关重要,直接影响器件的输出功率、增益和带宽等特性.本研究设计0.5 THz返波管电子光学系统,详细阐述电子枪和均匀永磁聚焦磁场的设计过程.根据返波管高频结构PIC(particle-in-cell)热腔模拟计算结果,设计符合电流发射要求且束流品质良好的电子枪,并结合理论分析,设计与之匹配的均匀永磁聚焦磁场.该电子光学系统主要工作和尺寸参数为:工作电压为23 kV时,阴极发射电流大于100 mA,电子通道的长度和直径分别为26 mm和0.2 mm.

Electron optics system(EOS)is an important part of a vacuum electronic device(VED)which includes electron gun, focusing system, and collector. The characteristics of focusing and transmission of electron beam in the EOS can affect the performances of VED, such as power, gain and bandwidth of device, etc. In this paper, we design the EOS for 0.5 THz backward wave oscillator(BWO), and describe the design procedures of the electron gun and the uniform permanent magnetic focusing system in detail. Firstly, based on the results of particle-in-cell(PIC)simulation, we design the electron gun which is satisfied with the required current amplitude and with good beam quality. Secondly, combined with the theoretical analysis, we devise the structure of uniform permanent magnetic focusing system matching the electron beam. The optimum parameters of EOS are as follows: the current emitted from the surface of cathode is greater than 100 mA at the operating voltage 23 kV, the length and diameter of the drift tube are 26 mm and 0.2 mm, respectively.