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