Wedge-shaped, large-aperture, dipole magnet designs for the Jefferson Lab FEL upgrade

Two types of dipole magnets were simulated and designed for the Thomas Jefferson National Accelerator Facility FEL upgrade. The magnets are to operate in series with a common power supply, and to provide /spl sim/0.01% accuracy of the field amplitude and field integral over a large aperture. The wedged magnets have quite different angles and effective length-to-aperture aspect ratios. The most difficult design problem was to provide high field quality in the magnet having a small aspect ratio /spl sim/2.7 and a 20/spl deg/ wedge angle. A design was developed which enabled small adjustments to be made before and after installation of the magnets. Trim coils, shims, and side sliders in the field clamps were introduced to compensate field gradients, non-uniformities, and parasitic fringe field effects. A number of design and adjustment issues are discussed.