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箔聚焦径向强流相对论电子束的研究

Study on the Transport of Foil-Focused Radial Intense Relativistic Electron Beam

【作者】 朱静

【导师】 刘庆想;

【作者基本信息】 西南交通大学 , 光学工程, 2008, 硕士

【摘要】 用导电箔引导强流相对论电子束的传输无需外加引导磁场,无功耗、结构简单,造价低廉、且可以最大限度的减小高功率微波器件的体积和重量,此方法已经成功的运用于引导轴向强流相对论电子束。本文将这一方法应用到径向高功率器件中用于引导径向强流相对论电子束的传输,主要微绕着径向漂移空间可以通过多大流强、如何选择合适的参数来实现箔引导径向强流相对论电子束进行了相关的理论研究和探讨。首先根据强流相对论电子束在漂移空间中的传输特点,做出一些适当的简化和假设,给出了合理的研究物理模型;利用迭代方法数值求解模型中漂移空间内束电子所满足的自洽方程,得到了三维有限尺寸漂移空间中束自洽电势分布;证明了迭代的收敛性和结果的正确性。在此基础上给出了一种计算漂移空间空间电荷限制流的方法,计算了径向漂移空间的空间电荷限制流;绘制了相关径向漂移空间中束流流强和束电子最小动能的分布图;给出了结合束电子初始能量和忽略电子传输过程中速度变化时空间的最大势能来判断径向漂移空间空间电荷限制流范围的依据。并且对于任意正交坐标系、任意漂移空间,只要知道束流的形状(任何的形状都适用)且束流满足相应的计算电场的假设,都可用所给算法求解其束流的自洽电势、电场,以及推广求空间电荷限制。基于对漂移空间中径向相对论电子束的电场和磁场分布的计算,推导了箔引导径向相对论电子束所需的平衡条件,讨论了其平衡的稳定性所需的条件;计算了束边缘电子的轨迹及相关的运动参数,结合平衡条件和边缘电子的轨迹及运动参数给出了径向器件中设置引导箔的理论依据。当束流流强较小时,束电子速度的变化可以忽略时,速度变化对电子密度分布的变化也可以忽略,本文推导了在此情况下忽略电子速度变化时径向漂移空间束自洽电场的解析分布;给出了相应的平衡条件、计算了其束边缘电子的轨迹;并给出了可忽电子速度变化的径向束流流强分布范围。利用此解析公式不仅可以清楚的反应相关物理规律,且可以大大节约计算时间和计算机资源。

【Abstract】 The measure transporting intense relativistic beam by transverse conducting foils has many advantages, for example, it do not need leading magnetic filed ,it works well without consuming any power ,its configuration is simple and price is cheap .Most of all it can cut down the volume and weight of the HPM generation mechanisms maximally . And this measure has been used for focusing axial intense relativistic beam successfully . In this paper , this measure will be used for focusing radial intense relativistic beam in radial HPM generation mechanisms , and the academic study and discuss will be made about how many intension the radial excursion space can transport and how to choose appropriate parameter for focusing radial intense relativistic beam .Firstly , according to the characteristic of the intense relativistic beam in excursion space, some proper predigestion and hypotheses will be made, and the appropriate physics model will be given ; then depending on the equation which the electrons of the beam satisfy in the excursion space of the model, a iterative arithmetic for calculating the electric potential of the beam in the excursion space is given, then its constringency and its validity are proved.Based on this arithmetic , a method for calculating the space-charge limiting current is found . Then the space-charge limiting current in the radial excursion space is calculated , the figure about the beam intension as a function of the minimal kinetic energy of the beam electron is plotted , and the principle for judging the range about the space-charge limiting current in the radial excursion space is gotten . In addition , for any excursion space in any orthogonal curvilinear coordinate , the electric potential , electric field of the beam and the space-charge limiting current can be calculated by using this arithmetic if the transverse of the beam is known and the beam satisfies the predigestion and hypotheses of the model.Based on the calculating of the electric filed and magnetic filed about the beam across through the excursion space , the balance equation for foil-focused radial relativistic electron beam is gotten , the stability of the equilibrium is discussed , and the method for calculating the track of those electrons in the beam’s brim as well as the parameters interrelated are given ,then the principle for chosen the distance between focusing foils is given by combining the balance equation and the request of the track.When the intension of beam is sparse the change of the beam electron’s velocity as well as the infection for the electron’s density aroused by the change of the beam electron’s can be ignored . In this condition , the analytic formula of the electric field is gotten ,then the he balance equation , the track of those electrons in the beam’s brim and their parameters interrelated are presented .Lastly , the rang in where the change of the beam electron’s velocity can be ignored is given. Using the analytic formula of the electric field can reflect the physical orderliness interrelated clearly as well as save calculating time and computer resource greatly.

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