12 research outputs found
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Heat transfer issues in high-heat-load synchrotron x-ray beams
In this paper, a short description of the synchrotron radiation x-ray sources and the associated power loads is given, followed by a brief description of typical synchrotron components and their heat load. It is emphasized that the design goals for most of these components is to limit (a) temperature, (b) stresses, or (c) strains in the system. Each design calls for a different geometry, material selection, and cooling scheme. Cooling schemes that have been utilized so far are primarily single phase and include simple macrochannel cooling, microchannel cooling, contact cooling, pin-post cooling, porous-flow cooling, jet cooling, etc. Water, liquid metals, and various cryogenic coolants have been used. Because the trend in x-ray beam development is towards brighter (i.e., more powerful) beams and assuming that no radical changes in the design of x-ray generating machines occurs in the next few years, it is fair to state that the utilization of various effective cooling schemes and, in particular, two-phase flow (e.g., subcooled boiling) warrants further investigation. This, however, requires a thorough examination of stability and reliability of two-phase flows for high-heat-flux components operating in ultrahigh vacuum with stringent reliability requirements
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The contact heat conductance at diamond-OFHC copper interface with GaIn eutectic as a heat transfer medium
Results of an experimental study of the contact heat conductance across a single diamond crystal interface with OFHC copper (Cu) are reported. Gallium-indium (GaIn) eutectic was used as an interstitial material. Contact conductance data are important in the design and the prediction of the performance of x-ray diamond monochromators under high-heat-load conditions. Two sets of experiments were carried out. In one, the copper surface in contact with diamond was polished and then electroless plated with 1 {mu}m of nickel, while in the other, the copper contact surface was left as machined. Measured average interface heat conductances are 44.7 {plus_minus}8 W/cm{sup 2}{minus}K for nonplated copper and 23.0 {plus_minus}3 W/cm{sup 2}{minus}K for nickel-plated copper. For reference, the thermal contact conductances at a copper-copper interface (without diamond) were also measured, and the results are reported. A typical diamond monochromator, 0.2 mm thick, will absorb about 44 W under a standard undulator beam at the Advanced Photon Source. The measured conductance for nickel-plated copper suggests that the temperature drop across the interface of diamond and nickel-plated copper, with a 20 mm{sup 2} contact area, will be about 10{degree}C. Therefore temperature rises are rather modest, and the accuracy of the measured contact conductances presented here are sufficient for design purposes
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Advantages of using a mirror as the first optical component for APS undulator beamlines
The advantages of using a mirror as the first optical component for an APS undulator beamline for thermal management, radiation shielding mitigation, and harmonic rejection are presented
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Thermal, structural, and fabrication aspects of diamond windows for high power synchrotron x-ray beamlines
Recent advances in chemical vapor deposition (CVD) technology have made it possible to produce thin free-standing diamond foils that can be used as the window material in high heat load, synchrotron beamlines. Numerical simulations suggest that these windows can offer an attractive and at times the only altemative to beryllium windows for use in third generation x-ray synchrotron radiation beamlines. Utilization, design, and fabrication aspects of diamond windows for high heat load x-ray beamlines are discussed, as are the microstructure characteristics bearing on diamond's performance in this role. Analytic and numerical results are also presented to provide a basis for the design and testing of such windows
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A preliminary analysis of the APS crotch design
A preliminary design analysis of the absorber plate of the proposed crotch for the APS bending magnet radiation is presented. Various design aspects including thermal and structural considerations, material selection, geometry, and cooling method are discussed and a number of recommendations are made
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Power distributions of the APS bending magnets and insertion devices
Relationships for computing the total power and the power density profiles of x-ray beams generated by bending magnets (BMs) and insertion devices (IDs) are given. A FORTRAN program called POWER for computing the angular distribution of power generated by an ID is developed and outlined. This interactive program is available on the APS VAX system by typing the command POWER, and a graphic display of the power profile is provided within the program. For users requiring simple analytical formulas, curve fits are used to approximate the ID and BM power distributions. The accuracy of such analytical forms depends greatly on how the curve fits are made and is generally within a few percent
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Potential of a beryllium x-ray lens
The use of refractive lenses for focusing x-ray beams has been the subject of publications since the early 1980s. Detailed calculations have been made for different shapes for the refractive lens: cylindrical, spherical, parabolic, and for a Fresnel-type refractive lens. The main drawback to the use of a single refractive lens to focus x-rays is that the index of refraction (n = 1 {minus} {delta}) is very close to 1, which results in a lens with a very long focal length. Recently Snigerov and others have suggested and experimentally demonstrated, using cylindrical-shaped lenses, that this problem of long focal lengths can be overcome by using many lenses in series. Each lens refracts the photon through a small angle, but the sum of these sequential changes in direction can be moderately larger. This increase in effective refraction angle reduces the focal length of the lens to a few meters or less and makes the multi-element lens a much more useful instrument for focusing x-rays. This paper, annualizes the expected performance of a lens consisting of a series of aligned hollow spheres in a beryllium substrate. The use of hollow spheres rather than hollow cylinders produces focusing of the x rays into a small focal spot in contrast to the single-directional focusing of the hollow cylinders, which produces a line focus. Two multi-element lenses have been constructed: one with 20 1-mm-diameter hollow spheres in an aluminum substrate, and one with 50 hollow spheres, 1 mm in diameter, in a beryllium substrate. Some construction details and calculations of the expected performance, are given for these two multi-element lenses
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Modeling the performance of water and liquid gallium cooled x-ray optical components: A comparison with experiment
Thermal and structural analyses of a water or liquid gallium cooled silicon crystal x-ray monochromator subjected to high heat loads have been carried out using a finite element method. From the computed strain distributions in the crystal rocking curves were produced and compared with experimentally measured rocking curves. Good agreement between the general width and shape of the calculated and measured rocking curve profiles was obtained. This initial agreement between calculation and measurement provides the foundation for the extension of our modeling to the prediction of x-ray optical component performance with more complex cooling schemes. Such elaborate cooling techniques may be required for the increased power loadings that will be produced by insertion devices in the next generation of low emittance storage ring sources such as the Advanced Photon Source (APS) to be constructed at Argonne National Laboratory. 5 refs., 6 figs
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Thermal and structural analysis of high precision beamline position monitors for synchrotron x-ray beams
The photon beam position monitors (PBPM) on the front end of the 7-GeV Advanced Photon Source (APS) synchrotron facility under construction at Argonne National Laboratory (ANL) are precision devices that measure spatial as well as angular positions of the x-ray beams. There exist two such devices on each APS front end, and they are set approximately 4 m apart. The required spatial resolution of these devices is of the order of a few microns; the required angular resolution is less than a micro-radian. These specifications make the material selection, design and stability of the PBPM very challenging tasks. The PBPM blades, which generate the photo-electrons signal from the x-ray beam, are indirectly cooled to prevent overheating by the x-ray beam. Even then, the blade is subject to severe thermal stresses. Prediction of the long-term material and position stability of the PBPM blade requires very careful heat transfer and stress analyses. In this paper, thermal analyses under the prevailing high heat flux from the incident beam and the corresponding stress analyses for various blade configuration are presented. As a result of these analyses, several options in design were developed and compared, including material selection for the blade and its structural detail