Design of current septum magnet for injection system of China Spallation Neutron Source

This paper reports the 2D/3D field calculations and designs of DC current septum magnet of injection system for rapid cycling synchrotron of the China Spallation Neutron Source (CSNS/RCS). The stray field ratio shrinks to 0.26 with 1 mmthick DT4 iron board, which greatly reduces the impacts on the cycling beam dynamics. Additionally, the detailed calculation of coil water cooling system has also been performed very carefully, which ensures stable running of the septum magnet. The results show that this type of septum magnet will the requirements of the long term stable running of CSNS/RCS on both physics and engineering design.