A NEW METHOD OF FINDING THE POLE PROFILE IN QUADRUPOLE MAGNETS FOR OBTAINING HIGH-FIELD QUALITY

The field quality in quadrupole magnets depends mainly on the pole pro file. One often uses a circular pole of optimized radius to reduce the field errors. Hyperbolic profiles which are modified at the pole edge s are also used. In the design of these magnets one first chooses a pr ofile and then calculates the error harmonics. Here we have described a new method in which we choose the error harmonics first and then fin d the profile thus ensuring that the field quality is good. The method can also be applied to other multipole magnets. (C) 1998 American Ins titute of Physics.