Modeling of heat-bump formation in x-ray optics under SR beams

Abstract

We have used a direct optical measurement of the distortion of the first silicon crystal of the CHESS A2 monochromator. The total X-ray power absorbed by the crystal was in the range of 2 to 190 Watts. The X-ray powers measured by a bolometer were in good agreement with the XOP calculations. In-situ optical measurements were used to measure the deformation of the crystal under the heat load between a 3-15 O angle of incidence. Simultaneously, ANSYS modeling of the effect of the heat load on the monochromator crystal with the cooling assembly was done. The measured slope error and the surface deformation profiles were in good agreement with the ANSYS simulations. A rocking curve method was used to measure the effect of a heat load on the diffraction properties of the monochromator for a range of beam-defining slit widths. We have found a good correlation between the FWHM of the rocking curves and the slope errors from the optical measurements.