增强器共振补偿方案

Resonance Stop-band Compensation Design for Booster Ring

  • 摘要: 强流重离子加速器的增强器用于强流重离子的极限累积和加速,其强流束产生的空间电荷效应使束流的工作点分布发散和漂移,并在工作点跨越低阶共振时造成离子束发射度增长甚至带来较大的束流损失。为消除低阶共振对离子束的不利影响,采用多极磁场来对6个低阶共振进行补偿。本文分析了增强器工作点附近的低阶共振,探讨了共振禁带的贡献项及相应的补偿方案,并通过数值模拟验证了增强器的共振补偿方案。结果表明,由增强器色品校正六极场引起的共振增强能通过补偿六极场进行消除,这将有利于增强器强流重离子束的实现。

     

    Abstract: Booster ring of the high intensity heavy-ion accelerator facility is designed to increase the ion beam intensity up to its maximum limit and boost beam energy. However accumulated intensive beam induces depressed tune spread and shift by space charge effect and overlapping with low-order resonance stop-bands, which leads to emittance growth and even serious beam loss. In order to counteract the impact upon the circulating ion beam by low-order resonances, multipole magnetic field was introduced into the booster ring for compensating the six low-order resonances. Low-order resonances near working point of the booster ring and contributions to their stop-bands were discussed in this paper. Scheme on each stop-band compensation was also presented and further verified by numerical simulation. The results show that enhanced resonances caused by sextuple field for chromaticity correction in booster ring can be eliminated by compensation sextuple fields. This work will help to implement intensive heavy ion beam at the booster ring.

     

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