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  • 1
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A newly designed, cryogenically cooled, thin Si crystal monochromator was tested at the European Synchrotron Radiation Facility (ESRF) beamline BL3. It exhibited less than 1 arcsec of thermal strain up to a maximum incident power of 186 W and average power density of 521 W/mm2. Data were collected for the thin (0.7 mm) portion of the crystal and for the thick ((approximately-greater-than)25 mm) part. Rocking curves were measured as a function of incident power. With a low power beam, the Si(333) rocking curve at 30 keV for the thin and thick sections was 〈1 arcsec FWHM at room temperature. The rocking curve of the thin section increased to 2.0 arcsec when cooled to 78 K, while the thick part was unaffected by the reduction in temperature. The rocking curve of the thin section broadened to 2.5 arcsec FWHM and that of the thick section broadened to 1.7 arcsec at the highest incident power. The proven range of performance for this monochromator has been extended to the power density, but not the absorbed power, expected for the Advanced Photon Source (APS) undulator A in closed-gap operation (first harmonic at 3.27 keV) at a storage-ring current of 300 mA. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An experiment was performed on beamline BL 3 at the European Synchrotron Radiation Facility to test the diffraction performance of a novel internally liquid-nitrogen-cooled, thin silicon crystal monochromator exposed to high heat loads. The beam parameters were chosen to closely match the conditions expected, in terms of absorbed power and beam profile, at the Advanced Photon Source (APS) for the closed gap undulator at 7 GeV and 100 mA. The cooled crystal was oriented at 11.4° in the symmetric Bragg geometry to diffract 30 keV x-rays from the Si(333) planes. The source was a 44-pole wiggler with the insertion device gap set at 25.0 mm corresponding to a deflection parameter, K, of 4.2. A tunable toroidal mirror was used to focus the wiggler beam onto the crystal. Double-crystal rocking curves were measured at several power values using different attenuators. The maximum total power absorbed by the 0.6-mm-thick crystal was 154 W at a storage ring current of 136 mA. The peak power density at normal incidence was about 420 W/mm2 corresponding to an absorbed peak power density on the crystal face of 83 W/mm2. No thermal-induced broadening of the rocking curve was observed above the average measured mounting/fabrication strain of 2 arcsec. Rocking curves were also measured as a function of coolant flow rate and pressure. No systematic broadening occurred due to flow-induced vibrations up to 6 l/min. It has been demonstrated that thin silicon crystals directly cooled with liquid nitrogen can handle high power density synchrotron beams comparable to what is expected for the APS undulators with no appreciable thermal deformation. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this paper, we report on the design and x-ray diffraction properties of cryocooled silicon single crystals exposed to the following wiggler beams: power density: 150 W/mm2, total power: 75 W and power density: 0.5 W/mm2, total power: 100 W. First, thermomechanical and engineering aspects of low-temperature crystal cooling are discussed, leading to two basic cooling geometries: internal cooling and side cooling. Experimental tests of both these cooling schemes at NSLS on beam lines X25 and X17 are then described and discussed. Finally, engineering problems related to the integration of cryogenic cooling on ESRF beam lines are presented.
    Type of Medium: Electronic Resource
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