带开口磁环的周期永磁聚焦系统的2维模拟

 由于目前常用的磁聚焦系统设计方法不能直接计算带有非轴对称开口磁环的磁系统，因此在行波管磁系统实验测试基础上，提出了双面带极靴的开口磁环体积等效概念：将开口磁环等效为相等体积磁性材料的2维轴对称磁环，两者都双面带极靴时轴上的磁场值相等。使用2维电磁计算软件FEMM计算了采用该等效模型后的周期磁聚焦系统的轴上磁场值，计算结果与带有开口磁环的实际系统测试值符合良好，两者相差仅3×10^-3 T。该2维等效模型能代替开口磁环进行计算。

2D simulation of periodic magnetic system with open magnetic rings

Based on the measured values on the axis of the magnetic system of the traveling wave tube(TWT),an axis-symmetrical equivalent model of magnetic ring,whose volume is equal to that of the practical non-axis-symmetrical magnetic ring with a gap,is presented. The magnetic field on-axis of this model including pole shoes on both sides is the same as that of the practical open ring with pole shoes. The computed values of the periodic magnetic system containing the equivalent models by the 2D FEMM are in agreement with the measured results of the real system with open magnetic rings.