The magnetic design and performance of the SRRC-U9 undulator

The magnetic design of the recently completed SRRC-U9 undulator system employs several enhancements to improve its performance. Side magnets to increase on-axis field augment the wedged-pole magnet geometry. Partial volume and partial strength end magnets and tuning bars achieve a zero-displacement, rapid turn-on, end-field configuration. Gap dependent normal and skew component ambient (earth) field compensation has been included in the design. The design includes bot active and passive end correction. Optical phase and trajectory shimming techniques have been employed to optimize performance. For k=10 the performance is greater than 80% of ideal through the seventh harmonic. At a K=6.4 the calculated spectral performance is greater than 80% through the thirteenth harmonic. A complete battery of magnetic measurements has fully established the field, spectral and beam dynamic characteristics of the undulator.