The multi-pass recirculating proton linac can significantly improve the usage efficiency of rf superconducting cavities by accelerating the proton beam through the same cavity multiple times. However, in order to achieve acceleration for different energy proton beams, longitudinal phase synchronous conditions among these beams have to be satisfied. In this paper, we propose a fixed field phase shifter system based on two superconducting bending magnets with an optimized field distribution to meet the synchronous conditions. Such a phase shifter provides both longitudinal phase delay and transverse focusing of multiple energy beams. Self-consistent macroparticle simulations including space-charge effects through the system show that the proton beam emittances can be well preserved after the phase shifter for multiple energy beams.

中文翻译：

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用于多通道循环超导质子直线加速器的固定场移相器

多遍循环质子直线加速器可以通过多次加速质子束穿过同一腔体来显着提高rf超导腔体的使用效率。但是，为了实现不同能量质子束的加速，必须满足这些束之间的纵向相位同步条件。在本文中，我们提出了一种基于两个超导弯曲磁体的固定磁场移相器系统，该磁场具有优化的磁场分布以满足同步条件。这种移相器提供了多个能量束的纵向相位延迟和横向聚焦。通过系统进行的包括空间电荷效应在内的自洽宏观粒子模拟表明，在移相多个能量束之后，质子束的发射率可以得到很好的保留。