摘要: 强流质子源与低能传输线（LEBT）是作为CIADS注入器的超导强流质子直线加速器的关键前端系统。目前LEBT采用双螺线管匹配结构设计，并安装有限制锥，但仍然不能避免少量H₂⁺和H₃⁺进入后端加速装置，这对直线加速器长期运行稳定性与可靠性会产生一定影响。为此，在LEBT加入分析磁铁对混合束（H⁺，H⁺2，H₃⁺）进行分离再注入后端加速器腔体，将是一个有效的方案。本研究对经过带有30度分析磁铁的LEBT的强流质子束的束流品质进行了模拟与实验测量。结果表明，分析磁铁高阶磁场的影响使经过分析磁铁的强流质子束束流品质变差，并且该影响随着束流包络的增大而增大。这些结果为CIADS注入器的低能传输线设计提供了参考依据。


High current proton source and the low energy beam transport(LEBT) are the key front-end systems for CIADS injector:high current proton linac accelerator. CIADS injector's LEBT adopts double solenoid matching structure, using a limit cone which can partially avoid H₂⁺ and H₃⁺ which injecting into the back-end linac accelerator may impact the long-term stability and reliability of the whole system. It will be an effective method to separate the hybrid ions (H⁺, H₂⁺, H₃⁺) by adding a dipole magnet at LEBT. In this article, we simulated and mesasured the high current proton beam quality behind the LEBT with a 30 degree dipole. The results show that the the proton beam quality is significantly effected by high-order magnetic fields of the dipole magnet, and the effect increases with the increase of the beam envelope. The achieved result is useful for the LEBT design of CIADS injector.