arXiv subjects

Yoshiteru Hidaka

Publications and source records attributed to Yoshiteru Hidaka.

4 recordsLinked to original sources

arXiv2026

Design and optimization of the NSLS-II lattice with complex bend replacement

The demand for brighter photon beams has driven the development of diffraction-limited storage rings with ultralow electron beam emittance. A complex bend (CB) lattice was recently proposed as an approach for the future NSLS-II upgrade. As a step toward this upgrade, NSLS-II plans to replace two existing electromagnetic dipoles with permanent-magnet CBs, providing the first experimental demonstration of the CB concept in a storage ring. This paper presents the linear optics design, nonlinear optimization, and machine error evaluation of the modified NSLS-II lattice. The optimized lattice provides sufficient dynamic and momentum apertures for off-axis injection and routine operation and can be corrected with the existing NSLS-II correction scheme. Scraper measurements near the planned CB installation location validate the beam aperture requirements used in the CB design.

physics.acc-ph↗

arXiv2026

Sextupole reduction via chaos suppression at the National Synchrotron Light Source II

We revisit the nonlinear lattice design approach for the National Synchrotron Light Source II (NSLS-II) storage ring. By suppressing chaos, we identify alternative sextupole configurations to the original design, which relied on the conventional strategy of simultaneously minimizing Resonance Driving Terms (RDT) and Amplitude-Dependent Detuning (ADD). These alternatives achieve comparable performance while requiring fewer sextupoles. A detailed comparison of two representative solutions is presented and supported by experimental validation. Our results show that the dynamic aperture correlates more strongly with global chaos than with individual RDTs, and that the importance of minimizing ADD may have been overstated in earlier design strategies.

physics.acc-ph↗

arXiv2024

Online regularization of Poincaré map of storage rings with Shannon entropy

Shannon entropy, as a chaos indicator, is used for online Poincaré map regularization and dynamic aperture optimization in the National Synchrotron Light Source-II (NSLS-II) ring. Although various chaos indicators are widely used in studying nonlinear dynamical systems, including modern particle accelerators, it is the first time to use a measurable one in a real-world machine for online nonlinear optimization. Poincaré maps, constructed with the turn-by-turn beam trajectory readings from beam position monitors, are commonly used to observe the nonlinearity in ring-based accelerators. However, such observations typically only provide a qualitative interpretation. We analyze their entropy to quantify the chaos in measured Poincaré maps. After some canonical transformations on the Poincaré maps, not only can the commonly used nonlinear characterizations be extracted, but more importantly, the chaos can be quantitatively calibrated with Shannon entropy, and then used as the online optimization objectives.

physics.acc-ph↗

arXiv2022

Convergence map with action-angle variables based on square matrix for nonlinear lattice optimization

To analyze nonlinear dynamic systems, we developed a new technique based on the square matrix method. We propose this technique called the \convergence map" for generating particle stability diagrams similar to the frequency maps widely used in accelerator physics to estimate dynamic aperture. The convergence map provides similar information as the frequency map but in a much shorter computing time. The dynamic equation can be rewritten in terms of action-angle variables provided by the square matrix derived from the accelerator lattice. The convergence map is obtained by solving the exact nonlinear equation iteratively by the perturbation method using Fourier transform and studying convergence. When the iteration is convergent, the solution is expressed as a quasi-periodic analytical function as a highly accurate approximation, and hence the motion is stable. The border of stable motion determines the dynamical aperture. As an example, we applied the new method to the nonlinear optimization of the NSLS-II storage ring and demonstrated a dynamic aperture comparable to or larger than the nominal one obtained by particle tracking. The computation speed of the convergence map is 30 to 300 times faster than the speed of the particle tracking, depending on the size of the ring lattice (number of superperiods). The computation speed ratio is larger for complex lattices with low symmetry, such as particle colliders.

physics.acc-ph↗