Center-Region Design and Initial Orbits in the Maryland University Isochronous Cyclotron

The center-region components of the Maryland cyclotron were designed with the maximum degree of flexibility permitted by geometrical restraints. Theoretical studies of initial orbits were based on electric field data, obtained with a fully automated electrolytic tank system. The desired magnetic field shape was determined in a 1/3 scale model magnet. A unique feature in the central magnetic field design is an adjustable cobalt-iron plug which permits to optimize the vertical focusing frequency at various field levels by balancing of the space charge forces. By proper positioning of the ion source and use of slits it is possible to operate either with large duty factor or to select a narrow pulse width.