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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Elucidation of the chemical environment for zinc species in an electron-rich zinc-incorporated zeolite

An electron-rich zinc-modified zeolite has been prepared by the incorporation of zinc vapor into the channels of a dehydrated HY (protonated zeolite Y). The chemical environment of the zinc species in the electron-rich zeolite has been elucidated on the basis of X-ray absorption spectroscopy. The formation of univalent zinc (Zn{sup +}) within the electron-rich zeolite was observed upon the irradiation of X-ray from either a synchrotron radiation source or a conventional X-ray diffractometer. The X-ray irradiation initiated the electron transfer from the electron-rich framework of zeolite Y to the nearby Zn{sup 2+} cations, generating Zn{sup +} species. The variation of the coordination environment of the zinc species upon interaction with water molecules has also been investigated. - Graphical abstract: The chemical environment of the zinc species in an electorn-rich zeolite has been elucidated on the basis of X-ray absorption spectroscopy. - Highlights: • An electron-rich zinc-incorporated zeolite has been prepared by chemical vapor reaction. • Univalent zinc is detected after the electron-rich zeolite is irradiated with X-ray. • The chemical environment of the zinc species is elucidated by X-ray absorption spectroscopy. • The coordination environment of the zinc species changes upon interaction with water molecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

On origin and destruction of relativistic dust and its implication for ultrahigh energy cosmic rays

Dust grains may be accelerated to relativistic speeds by radiation pressure, diffusive shocks, and other acceleration mechanisms. Such relativistic grains have been suggested as primary particles of ultrahigh energy cosmic rays (UHECRs). In this paper, we first revisit the problem of acceleration by radiation pressure and calculate maximum grain velocities achieved. We find that grains can be accelerated to relativistic speeds with Lorentz factor γ<2 by powerful radiation sources, which is lower than earlier estimates showing that γ could reach ∼10. We then investigate different destruction mechanisms for relativistic grains traversing a variety of environments. In solar radiation, we find that the destruction by thermal sublimation and Coulomb explosions is important. We also quantify grain destruction due to electronic sputtering by ions and grain–grain collisions. Electronic sputtering is found to be rather inefficient, whereas the evaporation following grain–grain collisions is shown to be an important mechanism for which the a ∼ 0.01–1 μm grains would be destroyed after sweeping a gas column N{sub coll}∼5×10{sup 19}–5×10{sup 20} cm{sup −2}. Relativistic dust in the interstellar medium and intergalactic medium (IGM) would be disrupted by Coulomb explosions due to collisional charging after traversing a gas column N{sub coll}∼10{sup 17} cm{sup −2} unless grain material is very strong. We show that photoelectric emission by optical and ultraviolet background radiation is also significant for the destruction of relativistic dust in the IGM. The obtained results indicate that relativistic dust from galaxies would be destroyed before reaching the Earth's atmosphere and unlikely to account for UHECRs.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Broadband impedance modeling and single bunch instabilities estimations of the advanced light source upgrade project

We report the Advanced Light Source Upgrade (ALS-U) is a 4th generation diffraction-limited soft x-ray radiation source, consisting of a new accumulator ring (AR) and a new storage ring (SR). In both rings coupling-impedance driven instabilities need careful evaluation to ensure meeting the machine’s high-performance goals. This paper presents the workflow followed in building the impedance models and the beam-stability analysis based on those models. We follow the commonly accepted approach of separating the resistive-wall and the geometric parts of the impedance; the former is obtained by analytical formulas, the latter by numerical electro-magnetic codes (primarily CST Studio software) with perfectly-conducting boundary conditions. Impedance budgets are established and pseudo-Green functions calculated to be used in beam dynamics studies. We also present various ways to cross-check simulation results for reliable impedance modeling. Finally, the crucial single-bunch instability current thresholds for various operation modes are determined and discussed.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2010

Test Study for Generation of Short Pulsed Synchrotron Radiation by Kicker Magnet in SPring-8 Storage Ring

A shorter pulse of synchrotron radiation is desired to measure a fast dynamic process exploration with a better resolution by material structure physics users. Among many complex schemes proposed for this purpose, we tested a simple scheme which makes use of a head-tail oscillation of a circulating electron beam with a small beam emittance. We have developed a new kicker magnet system which generated a short pulsed horizontal field of about 4.19 mT in 1.4 {mu}s pulse width with 1 Hz repetition. With this new developed kicker magnet system, we observed a bunch profile which leaned impressively between head and tail position by a visible light streak camera. Then we succeeded in achieving the shorter X-ray pulse width than the original one after a vertical slit being sliced by {approx}6 times. The observed X-ray pulse width was 7.38{+-}2.35 ps in FWHM.

43 PARTICLE ACCELERATORS↗
DOE OSTI2010

Development of Hard X-ray Imaging Optics with Two Pairs of Elliptical and Hyperbolic Mirrors

To form a magnified hard X-ray image with a 50 nm resolution, we have studied total reflection mirror optics with two pairs of elliptical and hyperbolic mirrors, which is called 'Advanced Kirkpatrick-Baez system'. A designed optical system has 200x and 300x magnifications in vertical and horizontal directions. Also diffraction limit size in the optical system is 40 nmx45 nm. We fabricated a pair of elliptical and hyperbolic mirrors for horizontal imaging with a figure accuracy of 2 nm using elastic emission machining (EEM), microstitching interferometry (MSI) and relative-angle-determinable stitching interferometry (RADSI). One-dimensional tests for forming a demagnified image of a slit were carried out at an X-ray energy of 11.5 keV at BL29XUL (EH2) of SPring-8. As a result, a shape beam with a FWHM of 78 nm was observed. This demonstrates that we realized one-dimensional Wolter optics that has a spatial resolution of 78 nm.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2010

FINEST: a high performance branch-line for VUV photon energy range gas phase studies at MAX-lab

We present a dedicated beamline branch for high flux and ultra-high resolution (R>100000) gas and vapor phase studies in the vacuum-ultra-violet (VUV) region of light on the undulator beamline I3, located on the 700 MeV MAX-III storage ring. The mechanical and optical design of the branch-line, the differential pumping setup as well as performance characteristics are presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2010

The Optimized Design of Undulators for the HiSOR Users Experiments

The HiSOR is a small racetrack type storage ring aiming for usage of synchrotron radiation. This ring is equipped with two undulators. One of them is a linear undulator and another is a helical one. These undulators serve high-flux VUV photon beams. Therefore, these beamlines are oversubscribed mainly for the high precision photo-electron spectroscopy experiments to investigate various materials. To solve this problem, we investigated possibilities to replace present undulators and beamline optics to those with better performance. One of such candidate undulator beamlines is a two-branch-beamline with a single elliptical undulator. Another candidate is a beamline equipped with a quasi-periodic undulator.

43 PARTICLE ACCELERATORS↗
DOE OSTI2010

Integration of an Atomic Force Microscope in a Beamline Sample Environment

We developed and optimised an optics-free Atomic Force Microscope (AFM) that can be directly installed on most of the synchrotron radiation end-stations. The combination of Scanning Probe Microscopies with X-ray microbeams adds new possibilities to the variety of synchrotron radiation techniques. The instrument can be used for atomic force imaging of the investigated sample or to locally measure the X-ray absorption or diffraction, or it can also be used to mechanically interact with the sample while simultaneously taking spectroscopy or diffraction measurements. The local character of these measurements is intrinsically linked with the use of the Atomic Force Microscope tip. It is the sharpness of the tip that gives the opportunity to measure the photons flux impinging on it giving beam position monitor features, or allows to locally measure the absorption coefficient or the shape of the diffraction pattern. As an example of the possibilities opened by the instrument we will show diffraction measurements performed on a Ge/Si island while being indented with the AFM tip providing local measure of the Young coefficient. Three ESRF beamlines are going to be equipped with this new instrument.

43 PARTICLE ACCELERATORS↗
DOE OSTI2010

The New ESRF Multilayer Facility: Progress and Perspectives

In view of the increasing need for high quality multilayer based x-ray optics the ESRF decided to upgrade its multilayer facility. During the last years a new deposition system was designed, installed, and commissioned. Since 2008 the new laboratory is operational and has produced its first optical elements for ESRF beamlines. The deposition system is based on magnetron sputtering and can cover optical surfaces up to 1000x150 mm{sup 2} with uniform or graded coatings. Four cathodes allow the use of conducting, insulating, and ferromagnetic target materials. This work will provide an overview on the machine conception and its overall performance, including a comparison with the formerly used system. It will be complemented by first fabrication results and perspectives for future projects in the framework of the ESRF Upgrade Programme.

43 PARTICLE ACCELERATORS↗
DOE OSTI2010

Calibration of a Gas Monitor Detector using a Cryogenic Radiometer for Measuring the Radiant Power of Extreme Ultraviolet Free Electron Laser at SPring-8

A gas monitor detector was calibrated to a cryogenic radiometer for measuring the radiant power of EUV-FEL (extreme ultraviolet free electron laser) at the wavelengths of 51 nm and 61 nm. The output signals of the gas monitor detector showed good linearity against the radiant power measured by the radiometer in the range from 6 {mu}W to 160 {mu}W. The calibration coefficients of the gas monitor detector are determined with the relative standard uncertainty of around 5 %.

43 PARTICLE ACCELERATORS↗
DOE OSTI2010

Fluorescence-type Monochromatic X-ray Beam-position Monitor with High-spatial Resolution for the NSLS-II Beamlines

We developed a fluorescence-type monochromatic X-ray beam-position monitor (X-BPM) with high-spatial resolution for end-station experiments at the initial project beamlines of the NSLS-II. We designed a ring array of multi-segmented Si PIN-junction photodiodes to use as a position sensor. Further, we integrated a low-noise charge-preamplification HERMES4 ASIC chip into an electronic readout system for photon-counting application. A series of precision measurements to characterize electronically the Si-photodiode sensor and the ASIC chip demonstrated that the inherent noise from the detector system is sufficiently low to meet our stringent requirements. Using a Gaussian beam, we parametrically modeled the optimum working distance to ensure the detector's best performance. Based upon the results from the parametric modeling, prototypes of the next versions of the X-BPM are being developed. In this paper, we describe the methodology for developing the new compact monochromatic X-ray BPM, including its instrumentation, detector modeling, and future plan.

43 PARTICLE ACCELERATORS↗
DOE OSTI2010

The RIKEN Materials Science Beamline at SPring-8: Towards Visualization of Electrostatic Interaction

In order to visualize molecular interaction by the experimental electrostatic potential analysis we have optimized the optical parameters and developed the high-resolution Debye-Scherrer camera at the RIKEN materials science beamline, BL44B2 of SPring-8. For the purpose the camera was designed to be equipped with the hybrid X-ray detector system. One is the conventional detector, the imaging plate readout off-line to carry out high d(interplanar spacing)-resolution measurements and the other is the CCD detector, which can be operated in a camera at variable distances for high angle-resolution measurements. In addition we have been developing an in-situ properties measurement system to visualize the electrostatic interaction completely synchronized with material functions.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

COMPARISON OF THE DIFFUSE H{alpha} AND FUV CONTINUUM BACKGROUNDS: ON THE ORIGINS OF THE DIFFUSE H{alpha} BACKGROUND

We compare the diffuse H{alpha} map of our Galaxy with the FUV (1370-1710 A) continuum map. The H{alpha} intensity correlates well with the FUV intensity. The H{alpha}/FUV intensity ratio increases in general with the H{alpha} intensity and the FUV hardness ratio (1370-1520 A to 1560-1710 A), implying that late OB stars may be the main source of the H{alpha} recombination line at high latitudes. The variation of the H{alpha} intensity as a function of the Galactic latitude is also very similar to that of the FUV intensity. The results likely suggest that not only the original radiation sources of the H{alpha} and FUV backgrounds but also the radiative transfer mechanisms responsible for the diffuse backgrounds are largely common. Therefore, we propose a scenario wherein the H{alpha} background at high latitudes is mostly composed of two components, H{alpha} photons produced by in situ recombination at the ionized regions around late OB stars and dust-scattered light of the H{alpha} photons originating from late OB stars.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2010

Quantum-dot-array diffraction grating with single order diffraction property for soft x-ray region

A gold transmission grating is used routinely to disperse the x-ray spectrum at the Z soft x-ray facility to measure the spectrum and temporal history of the absolute soft x-ray power emitted from z-pinch and hohlraum radiation sources. A quantum-dot-array diffraction grating (QDADG) of 250 lines/mm for soft x-ray is designed and fabricated for the first time according to the principle of binary sinusoidal transmission grating. The diffraction efficiencies of the grating are measured in the 150-300 eV photon energy range on the Beamline 3W1B of Beijing Synchrotron Radiation Facility. This article describes the basic concept and calibration techniques and presents calibration results. It is shown that the 250 lines/mm QDADG can be used to disperse light without higher-order diffractions in soft x-ray range, and the diffraction efficiencies of this grating are nearly constant (about 25%), which is beneficial in the spectrum analysis.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

The formation of massive primordial stars in the presence of moderate UV backgrounds

Radiative feedback produced by stellar populations played a vital role in early structure formation. In particular, photons below the Lyman limit can escape the star-forming regions and produce a background ultraviolet (UV) flux, which consequently may influence the pristine halos far away from the radiation sources. These photons can quench the formation of molecular hydrogen by photodetachment of H{sup –}. In this study, we explore the impact of such UV radiation on fragmentation in massive primordial halos of a few times 10{sup 7} M {sub ☉}. To accomplish this goal, we perform high resolution cosmological simulations for two distinct halos and vary the strength of the impinging background UV field in units of J {sub 21} assuming a blackbody radiation spectrum with a characteristic temperature of T {sub rad} = 10{sup 4} K. We further make use of sink particles to follow the evolution for 10,000 yr after reaching the maximum refinement level. No vigorous fragmentation is observed in UV-illuminated halos while the accretion rate changes according to the thermal properties. Our findings show that a few 10{sup 2}-10{sup 4} solar mass protostars are formed when halos are irradiated by J {sub 21} = 10-500 at z > 10 and suggest a strong relation between the strength of the UV flux and mass of a protostar. This mode of star formation is quite different from minihalos, as higher accretion rates of about 0.01-0.1 M {sub ☉} yr{sup –1} are observed by the end of our simulations. The resulting massive stars are potential cradles for the formation of intermediate-mass black holes at earlier cosmic times and contribute to the formation of a global X-ray background.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2011

Optimal focusing for a linac-based hard x-ray source

In spite of having a small average beam current limit, a linac can have features that make it attractive as an x-ray source: high energy, ultralow emittance and energy spread, and flexible beamline optics. Unlike a storage ring, in which an (undulator) radiation source is necessarily short and positioned at an electron beam waist, in a linac the undulator can be long and the electron beam can be adjusted to have a (virtual) waist far downstream toward the x-ray target. Using a planned CEBAF beamline as an example, this paper shows that a factor of 2000 in beam current can be overcome to produce a monochromatic hard x-ray source comparable with, or even exceeding, the performance of an x-ray line at a third generation storage ring. Optimal electron beam focusing conditions for x-ray flux density and brilliance are derived, and are verified by simulations using the SRW code.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Memory and CPU efficient coherent mode decomposition of partially coherent synchrotron radiation with subtraction of common quadratic phase terms

Application examples of a memory and CPU efficient coherent mode decomposition (CMD) method for wave-optics based simulation of the partially coherent undulator radiation propagation through a hard X-ray beamline in a 3rd generation synchrotron radiation source are presented. The high efficiency of the method is achieved thanks to the analytical treatment of the common quadratic phase terms that are developed in the phase of cross-spectral density (CSD) of partially coherent radiation at a distance from source. This treatment allows for a considerable, several orders of magnitude, reduction of the 4D CSD mesh density (and the memory occupied by the CSD) required for ensuring sufficient accuracies of wavefront propagation simulations with the modes produced by the CMD at a beamline entrance. This method, implemented in the “Synchrotron Radiation Workshop” open-source software, dramatically increases the feasibility of the CMD of 4D CSD for producing 2D coherent modes for a large variety of applications at storage rings and other types of radiation sources.

36 MATERIALS SCIENCE↗