横向聚焦波荡器磁场的计算与分析

Calculation and analysis of the magnetic field of a transverse focusing undulator

横向聚焦波荡器可用于电子束能量较低、β函数较小的情况。在现有横向聚焦波荡器设计方案的基础上,通过倾斜磁块端面和磁极面提出了几种不同结构的横向聚焦波荡器方案。利用三维磁场模拟程序Radia,对这些波荡器的聚焦场特性进行了模拟计算,对其聚焦特性与主要参数的关系进行了研究,并与现有其他横向聚焦波荡器的聚焦特性进行了对比。对弱聚焦和强聚焦两种情况,分别给出较好的结构方案。对于弱聚焦,平均聚焦梯度随中心场强的增大而略有增大,变化不明显;对于强聚焦,平均聚焦梯度随中心场强的增大而明显增大,呈高次曲线关系。

The transverse focusing undulators can be used for electron beams of low energy and smaller ＂fl＂ function. At present, there are some designs on transverse focusing undulators at home and abroad. This paper proposes several transverse fo cusing undulators of different magnetic structures which are based on the inclined surface of permanent magnet or/and pole blocks. Using the three-dimensional program Radia, the characteristics of focusing field of these undulators were calculated, the relationship between the focusing characteristics with the main parameters was studied, and performance of these undulators were also compared with other existing transverse focusing undulators. The results show that, for both the weak and strong focusing, several undulator schemes with better and simpler structures than the existing transverse focusing undulators were proposed. In addition, the average focusing gradient of weak focusing undulators does not increase significantly with the center magnetic field whereas the average focusing gradient of strong focusing undulators increases obviously with the center magnetic field.