Preserving the high source brightness with x-ray beam line optics

摘要

A first-order challenge facing developers of x-ray beam line optics at synchrotron sources lies in producing optics that faithfully deliver the brightness of the source, especially in the presence of adverse power loads. Once overcome, continued use of beam line optics in experiments often reveals a second-order challenge, that of preservation of the source brightness over time, especially as conditions such as the storage ring current change. This requires maintaining stability, with beam line optics, of the peaks, widths, and centroid positions of the various parameters that contribute to the brightness, the wavelength, position, and angle distributions of the delivered photon beam. Some ideas on the use of x-ray monochromators, mirrors, apertures, and position-sensitive monitors to sense and stabilize the brightness parameter distributions, as well as, methods to avoid or minimize transients in the first place, are presented. Examples based on experiences at the X25 wiggler beam line at the National Synchrotron Light Source (NSLS) are given.