The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Dean R. Haeffner - One of the best experts on this subject based on the ideXlab platform.
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the use of high energy x rays from the advanced photon source to study stresses in materials
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2005Co-Authors: Dean R. Haeffner, Jonathan Almer, U LienertAbstract:Abstract High-Energy X-Rays from third-generation synchrotron sources are opening new opportunities for the studies of stresses in materials. At the Advanced Photon Source (APS) 1-ID beamline, the combination of an undulator and specialized High-Energy X-ray optics produces a very brilliant photon beam in the 50–100 keV energy range. In this paper, three experiments using this capability are described. In the first the combined effects of residual and applied strain on the austenite and ferrite phases are measured in a duplex steel during deformation. The austenite is seen to yield prior to the ferrite. In the second experiment, High-Energy, small-angle scattering (HE-SAXS) and wide-angle scattering (WAXS) were used to study a thermal barrier coating. This allowed information to be obtained on the directionality of the pores in this material, as well as on gradients in the crystallographic texture and phase composition. In the final experiment, the behavior of an individual grain of an aluminum alloy was tracked during deformation using a 3-D X-ray microscope. This is the first phase of a project in which we intend to measure many more individual grains to deduce statistically significant effects of grain size, grain orientation, and effect of neighboring grains during deformation processes. The paper also briefly comments on possible future developments for High-Energy X-ray sources.
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Experimental characterization of APS undulator A at high photon energies (50-200 keV).
Journal of synchrotron radiation, 1998Co-Authors: S D Shastri, R J Dejus, Dean R. HaeffnerAbstract:The considerable intensity of Advanced Photon Source (APS) undulator A as a source of High-Energy X-Rays permits the performance of numerous types of experiments that require such photon energies. Measured and calculated properties, in the 50-200 keV range, of the X-ray beam from undulator A, installed in sector 1 of the APS, are presented. The flux spectra observed at various gaps agree well with calculations that incorporate the actual magnetic field within the device and the emittance and energy spread of the stored positrons. The field errors and energy spread cause the X-ray beam to lose undulator radiation properties at high energies, as seen in the smeared-out spectral harmonics and increased beam divergence, giving resemblance to a low-K wiggler source. Owing to the wiggler-like behavior in this photon-energy range, the optimal operating condition for undulator A is in the vicinity of the closed-gap setting, corresponding to a maximum critical energy.
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Experimental Characterization of APS Undulator A at High Photon Energies (50–200 keV)
Journal of Synchrotron Radiation, 1998Co-Authors: S D Shastri, R J Dejus, Dean R. HaeffnerAbstract:: The considerable intensity of Advanced Photon Source (APS) undulator A as a source of High-Energy X-Rays permits the performance of numerous types of experiments that require such photon energies. Measured and calculated properties, in the 50-200 keV range, of the X-ray beam from undulator A, installed in sector 1 of the APS, are presented. The flux spectra observed at various gaps agree well with calculations that incorporate the actual magnetic field within the device and the emittance and energy spread of the stored positrons. The field errors and energy spread cause the X-ray beam to lose undulator radiation properties at high energies, as seen in the smeared-out spectral harmonics and increased beam divergence, giving resemblance to a low-K wiggler source. Owing to the wiggler-like behavior in this photon-energy range, the optimal operating condition for undulator A is in the vicinity of the closed-gap setting, corresponding to a maximum critical energy.
Isaac Martens - One of the best experts on this subject based on the ideXlab platform.
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Towards comprehensive understanding of proton-exchange membrane fuel cells using high energy X-Rays
JPhys Energy, 2021Co-Authors: Isaac Martens, Raphael Chattot, Tim Wiegmann, Timo Fuchs, Olaf Magnussen, Laetitia Dubau, Frédéric Maillard, Jakub DrnecAbstract:For a future hydrogen economy, the development of cost effective energy conversion devices is a key issue. In this perspective, we discuss the use of high energy X-Rays for obtaining comprehensive insights into the complex processes which occur inside such devices, focusing on proton exchange membrane fuel cells. This probe enables structural characterisation under operating conditions on all relevant length scales, from the atomic-scale interfaces to complete stacks. This opens up possibilities to go beyond characterisation of the isolated components, towards an understanding of their interactions in the full system which determine the power output, efficiency and degradation pathways in operational devices.
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x ray transparent proton exchange membrane fuel cell design for in situ wide and small angle scattering tomography
Journal of Power Sources, 2019Co-Authors: Isaac Martens, Antonis Vamvakeros, Raphael Chattot, Maria Valeria Blanco, Miika Rasola, Janne PusaAbstract:Abstract We have constructed a 5 cm 2 proton exchange membrane hydrogen fuel cell optimized for transparency of high energy X-Rays. This cell allows for in situ elastic scattering measurements (WAXS, SAXS) during electrochemical operation with minimal trade-offs in cell performance vs benchtop designs, and is capable of reaching automotive current densities. A key feature is that the beam enters the cell at grazing incidence to the electrodes, massively increasing the effective pathlength and therefore the signal-to-background ratio. The 360 ∘ transparency in the plane of the sample permits imaging coupled with advanced techniques, such as X-ray diffraction computed tomography.
Miika Rasola - One of the best experts on this subject based on the ideXlab platform.
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x ray transparent proton exchange membrane fuel cell design for in situ wide and small angle scattering tomography
Journal of Power Sources, 2019Co-Authors: Isaac Martens, Antonis Vamvakeros, Raphael Chattot, Maria Valeria Blanco, Miika Rasola, Janne PusaAbstract:Abstract We have constructed a 5 cm 2 proton exchange membrane hydrogen fuel cell optimized for transparency of high energy X-Rays. This cell allows for in situ elastic scattering measurements (WAXS, SAXS) during electrochemical operation with minimal trade-offs in cell performance vs benchtop designs, and is capable of reaching automotive current densities. A key feature is that the beam enters the cell at grazing incidence to the electrodes, massively increasing the effective pathlength and therefore the signal-to-background ratio. The 360 ∘ transparency in the plane of the sample permits imaging coupled with advanced techniques, such as X-ray diffraction computed tomography.
S D Shastri - One of the best experts on this subject based on the ideXlab platform.
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Experimental characterization of APS undulator A at high photon energies (50-200 keV).
Journal of synchrotron radiation, 1998Co-Authors: S D Shastri, R J Dejus, Dean R. HaeffnerAbstract:The considerable intensity of Advanced Photon Source (APS) undulator A as a source of High-Energy X-Rays permits the performance of numerous types of experiments that require such photon energies. Measured and calculated properties, in the 50-200 keV range, of the X-ray beam from undulator A, installed in sector 1 of the APS, are presented. The flux spectra observed at various gaps agree well with calculations that incorporate the actual magnetic field within the device and the emittance and energy spread of the stored positrons. The field errors and energy spread cause the X-ray beam to lose undulator radiation properties at high energies, as seen in the smeared-out spectral harmonics and increased beam divergence, giving resemblance to a low-K wiggler source. Owing to the wiggler-like behavior in this photon-energy range, the optimal operating condition for undulator A is in the vicinity of the closed-gap setting, corresponding to a maximum critical energy.
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Experimental Characterization of APS Undulator A at High Photon Energies (50–200 keV)
Journal of Synchrotron Radiation, 1998Co-Authors: S D Shastri, R J Dejus, Dean R. HaeffnerAbstract:: The considerable intensity of Advanced Photon Source (APS) undulator A as a source of High-Energy X-Rays permits the performance of numerous types of experiments that require such photon energies. Measured and calculated properties, in the 50-200 keV range, of the X-ray beam from undulator A, installed in sector 1 of the APS, are presented. The flux spectra observed at various gaps agree well with calculations that incorporate the actual magnetic field within the device and the emittance and energy spread of the stored positrons. The field errors and energy spread cause the X-ray beam to lose undulator radiation properties at high energies, as seen in the smeared-out spectral harmonics and increased beam divergence, giving resemblance to a low-K wiggler source. Owing to the wiggler-like behavior in this photon-energy range, the optimal operating condition for undulator A is in the vicinity of the closed-gap setting, corresponding to a maximum critical energy.
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High-Energy x-ray experiments at the APS sector 1 beamlines
1997Co-Authors: D. R. Haeffner, S D Shastri, D. M. MillsAbstract:The goal of the SRI-CAT High-Energy x-ray program at Sector 1 of the Advanced Photon Source (APS) is to develop instrumentation and techniques that utilize the abundant potential of the APS as a source of photons in the 30 keV to 200 keV range. The initial efforts have been to characterize the High-Energy X-Rays from undulator A, to measure the scattering from several liquid and amorphous materials for comparison to neutron data, and to characterize optics for high-resolution Compton scattering. Results from these experiments will be presented along with a discussion of future Sector 1 High-Energy x-ray development.
J.b. Dubois - One of the best experts on this subject based on the ideXlab platform.
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thermal stability of nanocomposite metals in situ observation of anomalous residual stress relaxation during annealing under synchrotron radiation
Acta Materialia, 2010Co-Authors: J.b. Dubois, L. Thilly, P.o. Renault, Florence Lecouturier, M Di MichielAbstract:The thermal stability of nanocomposite metals (a nanostructured copper matrix embedding niobium nanotubes) is investigated via time-resolved in situ annealing under synchrotron High-Energy X-Rays. The diffraction peak profile analysis demonstrates that internal-stress relaxation begins in the Nb nanotubes at a temperature far below the bulk recrystallization temperature and follows size-specific regimes originating from a proximity effect with the nanostructured Cu matrix: the increased Cu–Nb interface surface disrupts internal-stress relaxation processes, confirming the larger thermal resistance of nanostructured materials.
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Thermal stability of nanocomposite metals : In situ observation of anomalous residual stress relaxation during annealing undersynchrotron radiation
Acta Materialia, 2010Co-Authors: J.b. Dubois, L. Thilly, P.o. Renault, Florence Lecouturier, And M. Di MichielAbstract:The thermal stability of nanocomposite metals (a nanostructured copper matrix embedding niobium nanotubes) is investigated via time-resolved in situ annealing under synchrotron High-Energy X-Rays. The diffraction peak profile analysis demonstrates that internal-stress relaxation begins in the Nb nanotubes at a temperature far below the bulk recrystallization temperature and follows size-specific regimes originating from a proximity effect with the nanostructured Cu matrix: the increased Cu–Nb interface surface disrupts internal-stress relaxation processes, confirming the larger thermal resistance of nanostructured materials.