Printed-circuit magnets for the University of Maryland Electron Ring (UMER) - new developments

The short printed-circuit quadrupoles for UMER produce fields with small gradients that meet our needs for the focusing and bending of a 10 keV, 100 mA electron beam over a circumference of 11.5 m. The field quality of the magnets has been established [see W.W. Zhang et al., Phys. Rev. ST Accel. Beams 3, 122401 (2000)], but correcting elements are needed to compensate for quadrupole rotation errors that lead to undesirable beam rotations in the injector line as well as in the main lattice. The correcting elements consist of printed-circuit quadrupoles; that are mounted over the main quadrupoles, with a relative angle of 45 degrees. In this way, a skew quadrupole component can be easily, independently and electronically adjusted to rotate the quadrupole field. Results are presented of field measurements of the modified quadrupoles, as well as preliminary observations in the UMER injector, and corresponding computer simulations.