强流相对论电子束周期永磁聚焦系统的研究

发布时间：2018-09-13 05:50

【摘要】：高功率、高效率和小型化是目前大多数高功率微波源的主要发展方向。高功率微波源在强流相对论电子束下运行。聚焦系统是高功率微波源的重要组成部分,其体积、重量和能耗的优化对高功率微波源的高功率和小型化发展具有重要的意义。在众多的聚焦方式中,周期永磁(PPM,Periodic Permanent Magnets)聚焦具有重量轻、不消耗功率、杂散磁场小等优点,满足微波管体积小、重量小、能耗低的发展趋势,因此强流相对论电子束PPM聚焦系统的研究具有重要意义。本文即以强流相对论电子束PPM聚焦系统为研究对象,开展强流相对论电子束在PPM中的运动特性的研究、产生电子束的皮尔斯电子枪的设计、PPM的设计和过渡区优化设计等,在保证电子束的通过率和降低波动的同时,尽量减小系统的体积和重量。论文的主要工作包括:首先,概述了强流相对论电子束PPM聚焦系统的研究背景和意义,介绍了周期永磁聚焦系统的相关理论,包括PPM聚焦电子束的理论、PPM的设计方法、磁场过渡区相关原理以及电子枪的理论基础等。接着,研究了强流相对论电子束在PPM聚焦系统中的传输特性。在相对论条件下考虑电子质量变化和电子束自磁场,通过对最外层电子的受力分析,推导出强流相对论条件下电子束稳定传输所需的PPM磁场峰值计算公式,得到在考虑相对论情况下,电子束的布里渊磁场的修正系数。同时对上述理论推导开展了仿真研究,结果表明,电压500kV、电流3.6kA的理想强流相对论电子束能在推导的1倍理论磁场峰值下稳定传输,符合所得的磁场峰值与电流电压关系,验证了理论分析的正确性。然后,初步设计了强流相对论电子束PPM聚焦系统。研究在考虑电子束非层流性等实际情况下,磁场峰值的大小对电子束传输状况的影响。使用修正的Vaughan迭代综合法设计了皮尔斯电子枪,提供电子束,并与磁场峰值恒定的PPM建立起一体化仿真,结果表明当磁场峰值为理论值的1.1倍时,电子束通过率为100%,几乎无波动。最后,通过对PPM过渡区磁场的设计优化了强流相对论电子束PPM聚焦系统。首先研究了磁场周期对于电子束波动的影响,确定了周期的选择原则,然后再在一定的周期下研究了过渡区磁场峰值对强流相对论强流电子束波动的影响,结果表明PPM的恒定磁场峰值为0.9～1倍理论周期磁场峰值,过渡区第二磁场峰值为0.8～1倍恒定磁场峰值,第一磁场峰值在1～1.2倍恒定磁场峰值时,电子束波动可以得到改善,PPM的重量和体积相对减小。
[Abstract]:High power, high efficiency and miniaturization are the main development direction of most high power microwave sources. The high power microwave source operates under a high current relativistic electron beam. Focusing system is an important part of high power microwave source. The optimization of its volume, weight and energy consumption is of great significance to the development of high power and miniaturization of high power microwave source. Among the many focusing methods, periodic permanent magnet (PPM,Periodic Permanent Magnets) has the advantages of light weight, no consumption of power, small stray magnetic field and so on, which satisfies the development trend of microwave tube with small volume, small weight and low energy consumption. Therefore, it is of great significance to study the intense relativistic electron beam PPM focusing system. In this paper, the high current relativistic electron beam PPM focusing system is taken as the research object, the motion characteristics of the high current relativistic electron beam in the PPM are studied, the design of the Pierce electron gun which produces the electron beam and the optimization design of the transition zone, etc. At the same time, the volume and weight of the system are minimized. The main work of this paper is as follows: firstly, the research background and significance of the PPM focusing system of high current relativistic electron beam are summarized, and the related theories of the periodic permanent magnet focusing system are introduced, including the design method of the PPM focusing electron beam theory. The related principle of magnetic field transition region and the theoretical basis of electron gun, etc. Then, the propagation characteristics of high current relativistic electron beam in PPM focusing system are studied. Considering the electron mass variation and the electron beam self-magnetic field under relativistic conditions, by analyzing the force on the outermost electron, the formula for calculating the peak value of the PPM magnetic field for the stable transmission of the electron beam under the strong relativistic condition is derived. The correction coefficient of Brillouin magnetic field of electron beam is obtained under the condition of relativity. The simulation results show that the ideal relativistic electron beam with a voltage of 500kV and a current of 3.6kA can transport stably at the peak value of the theoretical magnetic field, which is in accordance with the relation between the peak value of the magnetic field and the current and voltage. The correctness of the theoretical analysis is verified. Then, the high current relativistic electron beam PPM focusing system is designed. Considering the non-laminar flow of electron beam, the effect of the peak value of magnetic field on the transmission of electron beam is studied. Using the modified Vaughan iterative synthesis method, the Pierce electron gun is designed to provide the electron beam, and the integrated simulation is established with the constant magnetic field peak PPM. The results show that the magnetic field peak value is 1.1 times of the theoretical value. The electron beam pass rate is 100, almost no fluctuation. Finally, the high current relativistic electron beam PPM focusing system is optimized by designing the magnetic field in the PPM transition region. The influence of the period of magnetic field on the wave of electron beam is studied, and the selection principle of period is determined. Then, the effect of peak magnetic field in transition region on the wave of strong relativistic high current electron beam is studied in a certain period. The results show that the peak value of the constant magnetic field of PPM is 0.9 ~ 1 times that of the theoretical periodic magnetic field, the peak value of the second magnetic field in the transition region is 0.8 ~ 1 times the peak value of the constant magnetic field, and the peak value of the first magnetic field is 1 ~ 1. 2 times the peak value of the constant magnetic field. Electron beam fluctuation can improve the weight and volume of PPM.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN015;TN101

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