强流束晕-混沌的外部磁场滑模变结构控制

 研究了周期性聚焦磁场通道中，束晕-混沌的外部磁场滑模变结构控制方法。通过选择适当的滑模函数，根据李雅普洛夫稳定性条件，推导出外部磁场的滑模变结构控制器。模拟结果表明，在控制条件下，混沌变化的束包络半径能被控制到匹配半径。将该方法应用在多粒子模型中，实施每隔一个磁场周期就调节一次磁场幅度的控制策略，可实现对初始分布为K-V分布离子束的束晕-混沌的有效控制，束平均发射度降低了80%左右，束晕强度因子变为0，束流质量得到了很好的改善，消除了束晕及其再生现象。由于外部磁场是可测和可调的物理量，控制器简单且利于实现，研究结果可为强流离子加速器中周期性聚焦磁场的设计与试验提供参考。

Controlling beam halo-chaos via sliding mode variable structure adjusting exterior magnetic field

A sliding mode variable structure control method was studied for controlling beam halo-chaos in the periodic focusing channels(PFCs) of high-current ion accelerator. The sliding mode variable structure controller based on Lyapunov function theory was presented. The analysis and simulation results demonstrate that the chaotic radius of envelope can be controlled to the matched radius via adjusting exterior focusing magnetic field. This method was also applied to the multi-particle model of the beam with the K-V distribution in the PFCs. Under the mono-periodical interval control condition, the average transverse emittances of ion beam was decreased by about 80%, the beam halos and its regeneration could be eliminated, the qualities of high current beam become better. This method is easy to