Quadrupole singlet focusing for achromatic parallel-to-parallel devices

A first order achromatic magnetic deflection system for use in conjunction with a charged particle accelerator is realized from a stepped gap magnet wherein charged particles propagating through the system are subject to at least two adjacent homogeneous magnetic fields in adjacent regions in traversing one-half of a symmetric trajectory through the system. A quadrupole singlet element Q of adjustable focal length disposed substantially at the entrance plane of such a symmetric system makes possible the coincidence of the waists of the beam in both the vertical (transverse) and (radial) bending planes. (author)