AXIAL MAGNETIC FIELD PRODUCED BY RADIALLY MAGNETIZED PERMANENT MAGNET RING

Yoshihisa Iwashita
Accelerator Laboratory, Nuclear Science Research Facility
Institute for Chemical Research, Kyoto University
Gokanosho Uji, Kyoto 611, JAPAN

Abstract

Axial magnetic field produced by a radially magnetized permanent magnet ring was investigated. The magnet ring can produce a magnetic field on the axis higher than the remanent field of the magnet material based on the perpendicular field superposition. Because of the direction of the magnetization, the magnet system can be covered by an iron case, and then the stray flux outside the case is small. The magnet system has no iron pole piece except for the return poles of the iron case on both ends which are usually required for magnetic field shielding. A compact strong Permanent Magnet Symmetric lens was fabricated and the measured magnetic field agreed with PANDIRA calculation. For wider usage, it is desirable that the strength of the lens can be varied. One method to give the strength variability is presented. The axial magnetic field may also be applicable to the mirror field of the ECR (Electron Cyclotron Resonance) ion source. One example for that purpose is also presented.
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