Three water-cooled pin-post monochromators, to be used on a wiggler beamline at the Advanced Photon Source (APS), were built with the heat exchanger engineered to provide very high heat transfer. The geometry of the heat exchanger as well as calculated data on the heat transfer will be presented. Before using the monochromators on the beamline, they were checked by x-ray diffraction topography. Reflections (333) and (220) in Bragg case were utilized. In all crystals, similar patterns of strain in the diffracting silicon layers were revealed, which can be attributed to the geometry of the heat exchangers, the bonding technology, and the thickness of the top layer. Conclusions about construction of future pin-post monochromators have been drawn.
This paper describes the specifications, design, and fabrication of a 1.2 meter long ultra high vacuum silicon mirror for use as the first optical element on an x-ray beamline at APS. The mirror, which is 1200 mm by 90 mm by 120 mm in size, intercepts the incident x-ray beam at 0.15 degrees. The thermal power incident on the mirror is 1.2 kW with a peak heat flux of 0.38 W/mm2. The heat is removed by flowing water through a set of channels configured in the face plate of the mirror. Various aspects of this mirror, including its purpose, utility, expected thermal and structural performance, cooling design, UHV provision, support and mounting, surface figure and finish, bonding of the cooling conduits, and other manufacturing steps are discussed.
A-high-heat-load, horizontally deflecting/focusing mirror is designed for installation on an APS undulator beamline. The main design objective has been to keep the total tangential RMS slope error, including the thermally induced component, to less than 2 (mu) rad with an absorbed beam power on the mirror of 2 kW and a peak flux of 3.2 W/mm2. Extensive examination of various design parameters and detailed thermal/structural analyses has resulted in a mirror design that meets the tight slope-error requirement. Design features include a silicon substrate, a tailored pin-post cooling scheme, a moderate coolant flow rate, primary and secondary cooling areas, a multi-strip coating on the reflecting surface, and inlet/outlet cooling manifolds through an attached Ni-Fe mounting structure.
High energy insertion devices, used as x-ray monochromators on synchrotron storage rings, require high performance cooling of the primary optic. Monocrystalline materials, such as silicon, inherently provide crystal lattice properties suitable for x-ray diffraction. Silicon, provides excellent thermal and structural properties as well. Free electron lasers also require high performance heat exchanger technology for mirrors. A highly efficient approach to cooling, called `pin post cell,' was developed and fully validated in silicon. However, an additional criteria is imposed on the optic when used as a diffractive crystal. The crystalline structure of the material must not be altered during any step of fabrication. A test program has been completed which evaluated the existing fabrication technology for crystal lattice distortion. X-ray diffraction test results are presented. Currently, we are fabricating an actively cooled crystal that will undergo dynamic testing on the CHESS F2 beamline later this summer.
The high power levels found in modern synchrotrons require the use of cooled beamline optics in order to maintain optical distortion at acceptable levels. The best cooling methods are those which give acceptable distortion levels both economically and reliably. We review analytical studies we have performed on a number of cooled optics for synchrotron beamlines. Studies involving a wide range of power loadings, beam profiles, and optic geometries are discussed.
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