采用3D particle-in-cell(PIC)数值模拟方法, 研究高品质高能质子束经由脉冲电流螺线管传输并聚焦于远端的情况。模拟结果表明:初始时刻中心能量为250 MeV, 能散度为10%, 空间发散角小于15 mrad的质子束, 通过长度为760 mm、中心磁感应强度为10.87 T的通电螺线管, 可以被聚焦于距离质子源约2.5 m的远端, 焦斑横截面直径约为1.2 mm, 小于模拟初始时刻的1.8 mm, 质子数目的损失小于3%。研究结果表明利用通电螺线管来传输和调控高能质子束流的方案是可行的。该方案可用于优化质子束流品质, 促进激光驱动质子加速在癌症治疗等对质子束单能性和发散角要求较高的领域得到早日应用。

Based on 3D particle-in-cell (PIC) numerical simulation method, the high quality, high energy proton beam is transmitted and focused on the far end via a pulse current solenoid. Simulation results show that proton beam with peak energy of 250 MeV, energy spread of 10% and a spatial divergence angle less than 15 mrad can be focused on a spot 2.5 m away from the proton source, after transported in a 760-mm pulse power solenoid under magnetic field strength of 10.87 T. The focal spot cross section diameter is 1.2 mm, less than the initial proton beam spot size; meanwhile, the number loss of proton beam is less than 3%. We conclude that it is feasible to use a powered solenoid to transmit and regulate a high energy proton beam. This scheme can be used to optimize the proton beam quality and promote the laser-driven proton acceleration to be applied early in the fields such as cancer treatment, where high proton beam unipotency and small divergence angle are required.