用于多粒子模拟中束线设计的软边缘四极杆的解析描述
Analytic descriptions of soft-edge quadrupoles for beamline design in multi-particle simulations
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中文总结 AI 辅助
研究多粒子模拟中束线设计里软边缘四极杆的场，给出描述其包括高阶像差的解析公式，先回顾特定解析模型并扩展，以TRIUMF的DarkLight实验光学设计为例展示在相关代码中的实现。
中文摘要 AI 辅助
所有物理四极杆都有边缘场衰减，会产生固有高阶像差。在设计用于捕获和传输大发射度束流的具有强纵向紧凑光学元件的束线时，考虑这些像差尤为重要。本文给出了相对简单的解析公式，用于描述四极杆的场，包括其高阶像差，以用于束线设计。回顾了由$\mathrm{sech}^2$强度函数描述的四极杆解析模型，随后将其扩展到强度函数遵循tanh函数的四极杆，并将四极杆的有效长度作为自由参数。以TRIUMF的DarkLight实验的光学设计为例，展示了这些解析场描述在包络代码TRANSOPTR和多粒子代码GEANT4及FLUKA中的实现。
英文摘要
All physical quadrupoles have a fringe field falloff, giving rise to intrinsic higher order aberrations. It is especially important to consider these aberrations when designing beamlines with strong, longitudinally cramped optics used to capture and transport large emittance beams. This paper presents relatively simple analytical formulae which describe the fields of quadrupoles including their higher order aberrations for implementation in beamline design. We review the analytic model for quadrupoles described by a $\mathrm{sech}^2$ strength function and subsequently expand it to quadrupoles whose strength function instead follows a tanh function, adding the effective length of the quadrupole as a free parameter. The implementation of these analytic field descriptions in envelope code TRANSOPTR and multi-particle codes GEANT4 and FLUKA is presented using the optics design of the DarkLight experiment at TRIUMF as example.
