Contact-cooled U monochromators for high heat load x-ray beamlines (original) (raw)
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Contact-cooled U monochromators for high heat load x-ray beamlines
High Heat Flux Engineering III, 1996
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/rnm2. As such,fur the present application, it is compatible with the best internally cooled crystal monochromators. 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 are avoided. Last, by appropriate cooling of the crystal, tangential slope error can be substantially reduced.
Performance of synchrotron X-ray monochromators under heat load
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2001
In this paper we present the details of the finite element modeling (FEM) procedure used to calculate the thermal deformation generated by the X-ray power absorbed in silicon crystals. Different parameters were varied systematically such as the beam footprint on the crystal, the reflection order and the white beam slit settings. Moreover, the influence of various cooling parameters such as the cooling coefficient and the temperature of the coolant were studied. The finite element meshing was carefully optimized to generate a deformation output that could be easily read by a diffraction simulation code. Comparison with the experiments shows that the peak-to-valley slope error calculated by the FEM is an excellent approximation of the rocking curve width for a liquid nitrogen cooled silicon (3 3 3) crystal, and a quite good approximation for significantly deformed silicon (1 1 1) crystals. #
Design of an adaptive cooled first crystal for an x-ray monochromator
1994
We report here on the design of the first crystal in an x-ray monochromator for E.S.R.F. beam lines. This crystal is a thin silicon foil bonded to a cooled beryllium support. A system of piezoelectric actuators is used to counterbalance the deformations induced by synchrotron beams. This work was carried out by the C.E.A. in collaboration with the E.S.R.F. and the LASERDOT Company (Aerospatiale Group).
SPIE Proceedings, 1996
The submitted manuscript has been created by the University of Chicago as Operator of Argonne National Laboratory ("Argonne") under Contract No. W-31-109-ENG-38 with the U.S. Department of Energy. The U.S. Government retains for itself, and others acting on its behalf, a paid-up, nonexclusive, irrevocable worldwide license in said artkle to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.
SPring-8 standard X-ray monochromator
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2001
A systematic alignment method is described for fixed-exit position operation of SPring-8 standard monochromator in rotated-inclined geometry. Results of high-heat-load test showed the water-cooled pin-post crystal combined with the geometry well surpass 400W/mm2 power density of the X-ray undulator radiation.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2001
The aim of this work is to generate the rocking curves of monochromators exposed to heat load in synchrotron radiation beams with a computer code performing diffraction calculations based on the theory of Takagi and Taupin. The model study starts with the calculation of deformation by finite element analysis and from an accurate characterization of the incident wave and includes the simulation of the wavefront propagation between the first and the second crystal (analyzer) of a double crystal monochromator. A monochromatic plane wave as well as a polychromatic spherical wave approach is described. The theoretical predictions of both methods are compared with experimental data measured in Bragg geometry and critically discussed. #
The performance of a cryogenically cooled monochromator for an in-vacuum undulator beamline
Journal of Synchrotron Radiation, 2003
The channel-cut silicon monochromator on beamline ID09 at the European Synchrotron Radiation Facility is indirectly cooled from the sides by liquid nitrogen. The thermal slope error of the diffracting surface is calculated by ®nite-element analysis and the results are compared with experiments. The slope error is studied as a function of cooling coef®cients, beam size, position of the footprint and power distribution. It is found that the slope error versus power curve can be divided into three regions: (i) The linear region: the thermal slope error is linearly proportional to the power. (ii) The transition region: the temperature of the Si crystal is close to 125 K; the thermal slope error is below the straight line extrapolated from the linear curve described above. (iii) The non-linear region: the temperature of the Si crystal is higher than 125 K and the thermal slope error increases much faster than the power. Heat-load tests were also performed and the measured rocking-curve widths are compared with those calculated by ®nite-element modeling. When the broadening from the intrinsic rocking-curve width and mounting strain are included, the calculated rocking-curve width versus heat load is in excellent agreement with experiment.
Advanced Photon Source undulator beamline tests of a contact-cooled silicon u-shaped monochromator
1997
At the Advanced Photon Source (APS), undulator insertion devices are capable of producing x-ray beams with a total power of about 5 kW and normal incidence heat fluxes of about 170 W/mm2 at 30 m from the source. On beamlines in which the first optical element is a mirror, the reflected beam from the mirror still carries considerable power and power density. Depending on its location, the monochromator downstream of the mirror might be subject to 300 W total power and 5 W/mm2 normal incidence heat flux. Thus, it is still necessary to carefully design a monochromator that provides acceptable performance under these heat loads. A contact-cooled u-shaped monochromator may be used in this case. The main feature of the u-shaped monochromator is that, by carefully selecting the geometry and cooling locations, it passively corrects for some of the thermally induced crystal distortions. We present experimental and computational results of a contact cooled u-shaped monochromator tested on an ...