Design of a fifth-order achromat

A repetitive system free of all aberrations up to the fifth order was desig ned based on a recently developed analytical theory that, in principle, all ows the design of such achromats to an arbitrary order (Wan and Berz, Phys. Rev. E 54 (1996) 2870; Wan, Ph.D. Thesis, Michigan State University, 1995) . It serves as an example to show that complete correction of aberrations i s possible beyond order three, which is the highest order achieved before ( Dragt, Nucl. Instr. and Meth. A 258 (1987) 339; F. Neri, in: Berz, McIntyre (Eds.), Proc. Workshop on High Order Effects). Instead of repetition of identical cells, which is widely used in achromat design based on normal form theory, we utilize cells which are obtained fro m the original ones through mirror imaging about the x-y plane, which corre sponds to a reversion. In our design, the second half of the ring is the re version of the first one, and two turns make a fifth-order achromat. A poss ible application of repetitive high-order achromats being time-of-flight sp ectroscopy, the resulting ring was analyzed with respect to dynamic apertur e and energy resolution using maps of orders nine and higher. (C) 1999 Else vier Science B.V. All rights reserved.