Design of a high throughput grazing incidence monochromator for SURF II

Optimization and ray trace calculations have been completed for a high throughput, toroidal grating monochromator. Several unique features have been incorporated into the design. The instrument will use the electron beam as the entrance slit, taking advantage of the small vertical beam size and high brightness of SURF II. The grating will be placed as close as possible to the storage ring and will intercept 51 mrad of horizontal orbit and below 500 A, the full vertical light output. Three different gratings will be used to cover the ranges 30-90, 80-200 and 150-600 A. Normally, multi-grating instruments vary only the grating ruling spacing to change ranges, keeping the toroid and monochromator geometries identical in the different ranges. This instrument will be optimized independently in each range using the optimum toroid and monochromator geometries. As a result, the exit arm will change in going from the long to the middle wavelength range and the included angle will change from 162.20 to 1730 in going to the shortest wavelength range. (orig.)