Aberrations of single magnetic quadrupole lenses

Abstract

A number of analytical instruments make use of strong focusing magnetic quadrupole lenses. Such lenses suffer from aberrations which may degrade the performance of the instruments. This paper presents a modification of the grid shadow method which may be used to measure the aberrations of magnetic quadrupole lenses. The method is applied to a system which consists of a single quadrupole and a single octupole and the third order effect of the octupole is shown to be in good agreement with theory. The method is also applied to measure the second and third order parasitic aberrations of the single quadrupole lens components of the Melbourne Proton Microprobe. © 1987.