Cylindrical Circular and Elliptical, Toroidal Circular and Elliptical Multipoles Fields, Potentials and their Measurement for Accelerator Magnets

Abstract

Recent progress in particle accelerator tracking has shown that the field representation is one of the major limits of the prediction accuracy especially for machines, whose aperture is fully filled by the beam and thus higher the artefacts created by higher order modes have to be thoroughly understood.The standard tool for field presentation today are cylindrical circular multipoles due to their straight forward correspondence to the Cartesian coordinates. In this paper we extend the standard approach to other coordinate systems, show how these can be measured next to their realisation in measuring the SIS100 Magnets for the FAIR project.

Explicit symplectic integrator for particle tracking in s -dependent static electric and magnetic fields with curved reference trajectory

“…A similar approach is possible in the case that the reference trajectory has some non-zero curvature. Expressions for "curvilinear multipoles" (multipole fields around curved reference trajectories) have been given by McMillan and others [7][8][9][10], and have been implemented in the tracking code Bmad [11]. However, the available expressions are not ideal for use where the potential is given in purely numerical form.…”