Making dipoles to spectrometer quality using adjustments during measurement

Twenty-seven window frame dipole magnets requiring spectrometer-like fields were made for the IR-FEL at the Thomas Jefferson National Accelerator Facility. These magnets incorporate Purcell gaps, mu metal pole faces and adjustable field clamps. After outlining their specifications, this paper describes the processes used in magnet manufacturing, the program of magnetic mapping used, as well as the adjustments made to meet tight optics-driven requirements. Described are the measurements made to quantify fringe fields, verify field homogeneity, map core and integrated field as a function of current, and characterize the horizontal and vertical focusing terms designed into the dipoles. Also described are the techniques that were successfully used to tune individual magnets to meet the tight tolerancing of all these parameters.