Magnetic Field Features of Various Magnetic Circuits on the Sextupole Magnet

C. S. Hwang ； C. H. Chang ； T. C. Fan ； T. M. Uen ； P. K. Tseng

《Chinese Journal of Physics》 34卷5期 (1996/10) Pp. 1227-1236

並列摘要

In this study, two adjacent sextants were partially cut from one side of a sextupole magnet in order to accommodate the electron beam bending chamber associated with a three x-ray beam line chamber. The yoke cutting of these two sextants creates a different magnetic circuit which induces several forbidden fields. Meanwhile, the fundamental strength of this magnetic circuit is less than that of the normal on cut sextupole magnets in the storage ring. An induced forbidden field and the lessened sextupole strength originated from the saturation effect occurring at the magnet's yoke cutting side. Therefore, an extra closed-loop magnetic circuit is added across the two adjacent sextants to compensate for the yoke's smaller core area. This extra magnetic circuit can eliminate the saturation effect which induces asymmetric field behavior. It can also compensate for the lessened sextupole strength. In this work, the field distribution for various excitation currents related to the three magnetic circuits were measured. The field measurement results with various excitation currents tell us that the field saturation phenomena create the asymmetry field, forbidden field, and the lessened sextupole strength of the yoke cut magnetic circuit.