VARIABLE-FIELD PERMANENT-MAGNET DIPOLE

A new concept for a variable-field permanent-magnet dipole (VFPMD) has been designed, fabricated, and tested. The VFPMD 'Is a C-shaped secto r magnet with iron poles separated by a large block of magnet material (SmCo). The central field can be continuously varied from 0.07 T to 0 .3 T by moving an iron shunt closer or further away from the back of t he magnet. The shunt is specially shaped to make the dependence of the dipole field strength on the shunt position as linear as possible. Th e dipole has a 2.8 cm-high by 8 cm-wide aperture with -10 cm-long pole s.