A new way to improve the main magnetic field uniformity of a Lambertson magnet

Abstract

A Lambertson magnet is an indispensable device to the big scientific facilities all around the world especially the synchrotron radiation facilities and free electron lasers. The main magnetic field uniformity in the gap is always highly required to ensure that as small energy dispersion as possible is introduced to the particle beam. Instead of implementing shims on the pole face, a new way to improve the field uniformity is presented in this paper, namely adding holes in the opposite pole to the containing field free region. The relative size of the two added holes, the distance between them and their distance to the gap edge (depth) are all taken into consideration and carefully simulated to figure out their influence on the main magnetic field uniformity. Results show that the main magnetic field uniformity of Lambertson magnets can be improved when certain specific geometrical relations among the two added holes, the septum thickness and the width of the target uniform field region are observed.