A Numerical Method for the Calculation of Image Aberrations of Inhomogeneous Magnetic Sector Fields Between Conical Pole Faces

Owing to their increased dispersion magnetic analysers with inhomogeneous magnetic fields may be useful for various applications e. g. nuclear spectroscopy, mass spectroscopy, and isotope separation. This inhomogeneity may be aquired by conically shaped pole faces. BOERBOOM and T A S M A N gave an analytical treatment of these fields, which allows the calculation of aberrations for particles along the medium radius. For some applications e. g. simultaneous collection of more isotopes in an isotope separator it would be important to know how the quality of focus varies with increasing distance from the mean radius. In this paper a numerical method is described which allows a three dimensional ray-tracing throughout inhomogeneous magnetic sector fields. Some of the results have been published elsewhere l .