Contact-cooled U-monochromators for high heat load x-ray beamlines

This paper describes the design, expected performance, and preliminary test results of a contact-cooled monochromator for use on high heat load x-ray beamlines. The monochromator has a cross section in the shape of the letter U. This monochromator should be suitable for handing heat fluxes up to 5 W/mm(2). As such,for the present application, it is compatible with the best internally cooled silicon crystal monochromators operating at room temperature. There are three key features in the design of this monochromator. First, it is contact cooled, thereby eliminating fabrication of cooling channels, bonding, and undesirable strains in the monochromator due to coolant-manifold-to-crystal-interface. Second, by illuminating the entire length of the crystal and extracting the central part of the reflected beam, sharp slope changes in the beam profile and thus slope errors ate avoided. Last, by selecting appropriate crystal geometry and cooling locations, tangential slope error can be substantially reduced.