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arXiv 2103.06351physics.acc-ph
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具有大动态孔径和近似不变量的双弯和多弯消色差光栅设计

Design of double- and multi-bend achromat lattices with large dynamic aperture and approximate invariants

Yongjun Li, Kilean Hwang, Chad Mitchell, Robert Rainer, Robert Ryne, Victor Smaluk

摘要:

研究了一种设计具有近似运动不变量的非线性双弯和多弯消色差(DBA和MBA)晶格的数值方法。寻找这种非线性晶格的动机是费米实验室的可积光学测试加速器(IOTA),其设计基于具有两个运动不变量的可积哈密顿系统。虽然不可能为专用同步加速器光源储存环设计具有一个或多个精确运动不变量的消色差晶格,但可以调谐现有DBA和MBA晶格中的六极子和八极子以产生近似不变量。在我们的过程中,晶格调谐,同时最大限度地减少轮流的Courant-Snyder行动$J_x$和$J_y$在几个不同的幅度波动,同时最大限度地减少扩散的能量电子感应加速器的曲调。由此产生的晶格共享一些重要的功能与可积的,如一个大的动态孔径,轨迹局限于不变的环面,鲁棒性共振和错误,和一个大的振幅依赖的调谐扩展。与标称NSLS-II晶格相比,单束团和多束团不稳定性阈值增加,逐束团反馈增益可以降低。

英文摘要:

A numerical method to design nonlinear double- and multi-bend achromat (DBA and MBA) lattices with approximate invariants of motion is investigated. The search for such nonlinear lattices is motivated by Fermilab's Integrable Optics Test Accelerator (IOTA), whose design is based on an integrable Hamiltonian system with two invariants of motion. While it may not be possible to design an achromatic lattice for a dedicated synchrotron light source storage ring with one or more exact invariants of motion, it is possible to tune the sextupoles and octupoles in existing DBA and MBA lattices to produce approximate invariants. In our procedure, the lattice is tuned while minimizing the turn-by-turn fluctuations of the Courant-Snyder actions $J_x$ and $J_y$ at several distinct amplitudes, while simultaneously minimizing diffusion of the on-energy betatron tunes. The resulting lattices share some important features with integrable ones, such as a large dynamic aperture, trajectories confined to invariant tori, robustness to resonances and errors, and a large amplitude-dependent tune-spread. Compared to the nominal NSLS-II lattice, the single- and multi-bunch instability thresholds are increased and the bunch-by-bunch feedback gain can be reduced.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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