Field Design of the Main-Ring Bending Magnets of the NAL 200-GeV Synchrotron

Two types of bending magnets are used to match the beam width in the separated-function FODO lattice of the main ring of the NAL 200-GeV accelerator. Bending magnet B1 has an aperture of 5 in ?? 1.5 in, an overall dimension of 25 in ?? 16 in and a 12-turn coil; bending magnet B2 has an aperture of 4 in ?? 2 in, an overall dimension of 25 in ?? 14 in, and a 16-turn coil. With proper geometry and a small amount of pole-face crenellation, the good-field regions of these magnets extend over ~80% qf the aperture to beyond 20 kG. At 18 kG which corresponds to 400 GeV the saturation is only 3.7% and the excitation current is 4746 A. The magnetic -field design is performed using computer program TRIM. The factors of consideration and techniques involved in the design will be discussed.