Lambertson型切割磁铁漏场的3维模拟计算和优化设计

 Lambertson型切割磁铁的漏场对RCS中的束流运行有较大的影响，包括束流集体不稳定效应以及高阶共振效应，为了对该型磁铁进行优化，利用3维磁场模拟程序OPERA3D/TOSCA，对北京散裂中子源/快循环同步加速环（CSNS/RCS）引出Lambertson型切割磁铁进行了物理设计。通过对不同的磁铁设计方案进行3维模拟计算和优化发现，采用15 mm厚的切割板以及在屏蔽管出口处添加半径为200 mm、厚度为10 mm屏蔽帽的磁场屏蔽措施，将Lambertson型切割磁铁的横向漏场降低到主磁场的0.80‰（y方向）和0.36‰（x方向），可以满足CSNS/RCS环的束流动力学设计要求。

3D numerical simulations and optimization design of stray field of Lambertson septum magnet

The effects due to the stray field from Lambertson septum magnet are important, including beam high order resonance and unstable effect, etc, The 3D numerical simulations with OPERA3D/TOSCA code and the optimizing processes of design of Lambertson septum magnet were described in this paper. The simulations were performed for different models so that we could decrease the ratio of integrated stray field to integrated main field. After optimization of design, including increasing the thickness of septum to 15 mm and adding a shielding hat with radius of 200 mm and thickness of 10 mm, the ratios of transverse stray field to main field were 0.8‰(in y direction) and 0.36‰(in x direction). The results were satisfactory to the requirement of RCS beam dynamics.