CHROMATIC ABERRATION CORRECTING METHOD

PURPOSE:To correct chromatic aberration with a weak six-pole magnet and expand a dynamic aperture by using a magnet divided with a four-pole magnet into two and inserted with the fix-pole magnet between them and integrated. CONSTITUTION:A device is constituted of two deflecting magnets 1, a triplet consisting of a nonconvergent magnet 2, a convergent magnet 3, and a nonconvergent magnet 4 on the outside, and a convergent magnet 6 storing a six-pole magnet at the portion pinched by the deflecting magnets. A four-pole magnet storing this six-pole magnet is obtained by dividing an ordinary four-pole magnet into two and pinching the six-pole magnet between them. The six-pole magnet can be installed at the place where the betatron function is the maximum. The six-pole magnet can be operated most effectively, thus the chromatic aberration of the weak six-pole magnet can be corrected. A large dynamic aperture can be obtained.