Frequency analysis and dynamic aperture studies in ELENA with realistic 3D magnetic fields

从单圈映射学习动态孔径

Learning Dynamic Aperture from One-turn Maps

提出将动态孔径预测转化为图像分割问题，利用深度代理模型从编码的单圈映射直接学习粗粒度动态孔径，并在电子-离子对撞机电子储存环中验证了其泛化能力。

Accurate Taylor transfer maps for large aperture iron dominated magnets used in charged particle separators and spectrometers

For high-resolution separators like the projected Super-FRS at FAIR, an adapted and accurate ion-optical model considering realistic B-dependent magnet parameters is crucial in achieving the desired parameters (e.g. resolution) and to enable a fast optimization. Starting from the magnetic field measurements and simulations, rigidity-dependent Taylor transfer maps are generated for the Super-FRS preseparator dipole magnets. The effects of the magnetic saturation in the steel yoke on the image aberrations are analyzed.

Effect of the Sextupole Finite Length on Dynamic Aperture in the Collider Final Focus

In a collider final focus (FF) system chromaticity generated by FF quadrupoles is compensated by sextupole pairs with -I map in between to cancel geometrical aberrations. However, it works perfectly only for zero-length sextupole kicks; for realistic thick magnets only quadratic aberrations are cancelled exactly while higher order terms appear and may deteriorate the transverse dynamic aperture. The latter is particularly important for prospective projects of the future circular colliders based on the Crab-Waist collision approach where extremely low beta at IP generates very large chromatic e…

Advances on the modelling of the time evolution of dynamic aperture of hadron circular accelerators

Determining a model for the time scaling of the dynamic aperture of a circular accelerator is a topic of strong interest and intense research efforts in accelerator physics. The motivation arises in the possibility of finding a method to reliably extrapolate the results of numerical simulations well beyond what is currently possible in terms of CPU time. In earlier work, a proposal for a model based on Nekhoroshev theorem and Kolmogorov--Arnold--Moser theory was made. This model has been studied in detail and proved successful in describing the evolution of the dynamic aperture in numerical si…

Medical therapy and imaging fixed-field alternating-gradient accelerator with realistic magnets

NORMA is a design for a normal-conducting race track fixed-field alternating-gradient accelerator (FFAG) for protons from 50 to 350 MeV. In this article we show the development from an idealised lattice to a design implemented with field maps from rigorous two-dimensional (2D) and three-dimensional (3D) FEM magnet modelling. We show that whilst the fields from a 2D model may reproduce the idealised field to a close approximation, adjustments must be made to the lattice to account for differences brought about by the 3D model and fringe fields and full 3D models. Implementing these lattice corr…

圆形粒子加速器中非线性动力学的混沌指标

Chaos indicators for non-linear dynamics in circular particle accelerators

本文针对圆形粒子加速器中非线性动力学分析计算成本高的问题，在CERN大型强子对撞机真实磁聚焦结构模型中研究带Birkhoff权重的快速Lyapunov指标和反向误差法等先进混沌指标，验证了其识别混沌动力学的高效性和预测长期动力学孔径的潜力。