一种新型的有限截面电子束模型

A novel finite-size-beam model

为了解决电子束横波器件设计数值模拟中计算量大和可能不收敛等问题,提出了一种新型计算有限截面电子束空间电荷力的物理模型,用多个等半径的小圆来逼近电子束截面且考虑分束的截面积,推导出空间电荷自作用力计算式,并验证了其有效性.该模型解决了当两电荷靠近时库仑场趋于无限大的问题,避免了在计算中人为加入的防止计算发散的参数取值的任意性,并且克服了用柱坐标非均匀网格离散化电子束截面造成的误差,可以有效地用于研究电子速度离散、电子束电流截流、效率降低问题.

In order to solve the problem of large amount of calculation and possible non-convergence in numerical simulation of electron beam shear wave device design, this paper proposes a new physical model for calculating the space charge force of finite-size-beam, in which multiple small circles with equal radius are used to approximate the cross-section of electron beam and consider the cross-sectional area of the beam splitting, with the calculation formula of the space charge self-acting force derived and its effectiveness verified. This model solves the problem that two charges tend to be infinite when they are close together, so as to avoid the fictitious parameters added to prevent the divergence of the calculation, overcoming the error caused by discretization of electron beam cross section with cylindrical coordinate non-uniform grid. Thereby it can be effectively used to study electron velocity dispersion, electron beam current closure and efficiency decrease problem.