A permanent-magnet dipole with variable field strength and polarity

A prototype dipole magnet employing permanent-magnet rods has been designed and constructed. The magnet is able to change the magnetic field strength continuously as well as the polarity of the field direction by rotating the rods. The magnet has a special advantage of high-field production within a small open space available. The magnet of this type will be used for beam steering at an extraction channel for a planned negative ion acceleration in our cyclotron. Some properties of the magnet as well as the design studies, and the result of measurements are presented.