MICROCHANNEL WATER COOLING OF SILICON X-RAY MONOCHROMATOR CRYSTALS

The use in silicon x-ray monochromator crystals of water cooling channels with dimensions optimized for efficient heat transfer from silicon to water has been investigated. Such channels are typically about 40-mu-m wide and 400-mu-m deep. Procedures have been found for reliably producing microchannel-cooled crystals with very small amounts of residual strain. These crystals have been tested at a high-power wiggler beam line at the Cornell High Energy Synchrotron Source, using an x-ray beam having total power in excess of 250 W and normal-incidence power density greater than 5 W/mm2. Under these conditions, the surface-temperature rise of a typical microchannel-cooled crystal was less than 5-degrees-C, and degradation of the (111) rocking curve at 12 keV was very slight. The cooling efficiency is consistent with analytic calculations.