Numerical optimization of a low emittance lattice cell

Zhang, Tong; Huang, Xiaobiao

doi:10.1016/j.nima.2019.01.065

Cited by 4 publications

(2 citation statements)

References 17 publications

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“…12, which illustrates the linear optics for one cell. Note that several reverse bends are incorporated [26,27]. The main parameters are listed in Table II.…”

Section: Applied To Mbamentioning

confidence: 99%

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

Hwang

Mitchell

et al. 2021

Phys. Rev. Accel. Beams

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A numerical method to design nonlinear double-and multibend 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, 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 double-and multibend achromat 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 National Synchrotron Light Source-II lattice, the single-and multibunch instability thresholds are increased and the bunch-by-bunch feedback gain can be reduced.

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“…12, which illustrates the linear optics for one cell. Note that several reverse bends are incorporated [26,27]. The main parameters are listed in Table II.…”

Section: Applied To Mbamentioning

confidence: 99%

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

Hwang

Mitchell

et al. 2021

Phys. Rev. Accel. Beams

View full text Add to dashboard Cite

show abstract

“…In principle, the type of basis function can be selected in an arbitrary manner. E.g., in [9] step-like basis functions are used and truncated at a high order, and a particle-swarm based optimization is applied in the resulting high-dimensional parameter space.…”

Section: Introductionmentioning

confidence: 99%

Mathieu unit cell as a template for low emittance lattices

Riemann

2021

Phys. Rev. Accel. Beams

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The multi-bend achromat (MBA), which often serves as a building block for modern low-emittance storage rings, is composed of a repetition of unit cells with optimized optical functions for low emittance in the achromat center, as well as end cells for dispersion and optics matching to insertion devices.In this work, we describe the simplest stable class of unit cells that are based on a longitudinal Fourier expansion, transforming Hill equations to Mathieu equations. The resulting cell class exhibits continuously changing dipolar and quadrupolar moments along the beam path. Although this elementary model is defined by only three parameters, it captures a significant amount of notions that are applied in the design of MBAs. This is especially interesting as Mathieu cells can be viewed as an elementary extension of Christofilos' original model of alternating-gradient focusing.Mathieu cells can be used to estimate the range of reasonable cell tunes and put an emphasis on the combination of longitudinal gradient bending and reverse bending, as well as on strong horizontal focusing to reach emittances lower than the classic theoretical minimum emittance cell. Furthermore, the lowest emittances in this model are accompanied by small absolute momentum compaction factors.

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A Cross-Cell Interleaved Nonlinear Lattice for Potential NSLS-II Upgrade

Shaftan

et al. 2019

J. Phys.: Conf. Ser.

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An interleaved sextupole scheme using a cross-cell betatron phase cancellation technique is adopted as a candidate for a future upgrade to the NSLS-II lattice. The upgraded lattice will use as many NSLS-II installed magnets as possible, including 30 dipoles, which will create a triple bend achromat configuration. A 300 pm-rad horizontal beam emittance has already been achieved with the current configuration. The emittance can be further reduced to around 200 pm-rad with damping wigglers. Some new design concepts used in modern 4th-generation light sources, such as adopting longitudinal gradient bends and reverse bends, are incorporated into the design as well. The betatron phase-advance between sextupoles is designed to have a cross-cell interleaved cancellation pattern in the transverse planes. The dynamic aperture is sufficient to allow the conventional off-axis top-off injection. At the same time, a large energy acceptance looks promising and would ensure a sufficiently long beam lifetime.

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Numerical optimization of a low emittance lattice cell

Cited by 4 publications

References 17 publications

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

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

Mathieu unit cell as a template for low emittance lattices

A Cross-Cell Interleaved Nonlinear Lattice for Potential NSLS-II Upgrade

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