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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Demonstration of a high repetition rate capillary discharge waveguide

A hydrogen-filled capillary discharge waveguide operating at kHz repetition rates is presented for parameters relevant to laser plasma acceleration (LPA). The discharge current pulse was optimized for erosion mitigation with laser guiding experiments and MHD simulation. Heat flow simulations and measurements showed modest temperature rise at the capillary wall due to the average heat load at kHz repetition rates with water-cooled capillaries, which is promising for applications of LPAs such as high average power radiation sources.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Output characteristics of a 0.14 THz dual sheet beam backward wave oscillator based on a hole-grating slow wave structure

A novel backward wave oscillator (BWO) based on a hole-grating slow wave structure is proposed as a dual sheet beam millimeter wave radiation source. In this paper, we focus on the output characteristics of a 0.14 THz hole-grating BWO. The output characteristics of the hole-grating BWO, the conventional single-beam grating BWO, and the dual-beam grating BWO are contrasted in detail. 3-D particle-in-cell results indicate that the hole-grating slow wave structure can help to increase the maximum output power as well as lower the operating current density. Meanwhile, the hole-grating BWO shows good insensitivity to the differences between two sheet electron beams. These characteristics make the hole-grating BWO feasible to be a stable millimeter wave radiation source with higher output power.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Instrument Efficiencies and ISO-7503 - 16525

The International Standard for the Evaluation of Surface Contamination provides guidance on evaluating surface contamination, and is used to document clearance of buildings, materials, and equipment. A key component of the guidance is the determination of instrument efficiency based on the 2-pi emission rate of a traceable radiation source. Many projects implement portions of this guidance or apply the guidance incorrectly. These errors generally result in an overestimate of the instrument efficiency, resulting in an underestimate of the activity being measured and overly optimistic estimates of detectability. A review of the recommendations for developing instrument efficiencies is provided, and the aspects of the guidance that are most often neglected are identified. The impact of failing to properly determine the instrument efficiency is demonstrated using experimental data. Data were collected using traceable alpha and beta radiation sources at multiple source-to-detector distances using gas-proportional and dual-phosphor detectors. The results of these measurements demonstrate the importance of proper implementation of the guidance for determining instrument efficiency and assist reviewers in identifying situations where the guidance was not properly implemented. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2014

SU-C-19A-02: An Innovative Critical Organ Repositioner Device for Use During Radiotherapy Treatments

Purpose: In most radiation oncology applications the use of shape memory alloy (SMA) actuation can be extremely beneficial in sparing normal structures by relocating them away from the path of the external beam, or placing distance between the structure and radiation source such as in Brachytherapy. Implementation of this organ repositioner device in conjunction with IMRT could open new possibilities for dose escalation and significant dose reduction to normal tissues. Similarly, in high dose rate brachytherapy applications, the ideal effective dose may not be delivered to the target volume due to toxicity concerns to adjacent critical structures. Here we present a dual functioning device manufactured from SMA materials to: 1) provide a desirable tool to reposition the organ at risk away from the radiation source, and 2) facilitate localization when imaging the area. Methods: A Nitinol based actuator with controlled force and displacement will be incorporated in the design of an organ repositioner (e.g., a rectal marker) with the ability to recall a pre-defined shape at temperature T1 (body temp) and shift back to its original shape at temperature T2 (to facilitate removal). An open distal end permits the marker to function as a part of a barium delivery system. Results: An example of this SMA manufactured in our laboratory for atrial fibrillation radio frequency ablation is the esophagus SMA positioner, designed to position the esophagus away from the ablation area. This device shows the maximum strain in the deflected esophagus to be less than 3%. The prototype positioner deflected the organ at risk by 5 cm away from the site of ablation. Conclusions: The organ repositioner device is feasible for use in clinics, provides patient comfort due to its gradual deflection, and has dual functionality in repositioning the organ at risk as well as serving as a localization device.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

The study of oxygen molecules on Pt (111) surface with high resolution x-ray photoemission spectroscopy

By using high resolution x-ray photoelectron spectroscopy, we show that inelastic scattering of photoelectron at low temperature (30-50 K) generates two kinds of oxygen species on Pt (111) surface. Intense synchrotron radiation source dissociates oxygen molecules into chemisorbed atomic oxygen and induces the formation of PtO on the surface. Estimated coverage of dissociated atomic oxygen is 0.5 ML, suggesting possible formation of p(2x1) surface structure, while PtO coverage shows saturation coverage of 0.5 ML. Molecular oxygen dosed at 30 K undergoes thermally activated transition from physisorbed to chemisorbed state at around 40 K.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Effects of quartz particle size and water-to-solid ratio on hydrothermal synthesis of tobermorite studied by in-situ time-resolved X-ray diffraction

Hydrothermal synthesis process of tobermorite (5CaO.6SiO{sub 2}.5H{sub 2}O) has been investigated by in-situ X-ray diffraction using high-energy X-rays from a synchrotron radiation source in combination with a purpose-build autoclave cell. Dissolution rates of quartz were largely affected by its particle size distribution in the starting mixtures. However, the composition (Ca/Si) of non-crystalline C-S-H at the start of tobermorite formation was identical regardless of the quartz dissolution rate. An effect of water-to-solid ratio (w/s) was investigated for samples using fine particle quartz. Tobermorite did not occur with w/s of 1.7 but occurred with w/s higher than 3.0. Surprisingly, however, the dissolution curves of quartz were nearly identical for all samples with w/s from 1.7 to 9, indicating that the dissolution rate is predominated by surface area. Possible reaction mechanism for tobermorite formation will be discussed in terms of Ca and/or silicate ion concentration in the liquid phase and distribution of Ca/Si in non-crystalline C-S-H. - Graphical abstract: Time-resolved XRD data set was obtained at up to 190 deg. C under a saturated steam pressure. Tobermorite (5CaO.6SiO{sub 2}.5H{sub 2}O) formation reaction was investigated in detail for several different starting materials. Highlights: > Hydrothermal formation of tobermorite was monitored by in-situ XRD. > Ca/Si of C-S-H at the start time of tobermorite formation was determined. > The Ca/Si value was identical regardless of the quartz particle size in the starting mixture.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Demonstration of a ring-FEL as an EUV lithography tool

In this work, we present the required structure and function of a ring-FEL as a radiation source for extreme ultraviolet radiation lithography (EUVL). A 100 m-long straight section that conducts an extremely low emittance beam from a fourth-generation storage ring can increase the average power at 13.5 nm wavelength to up to 1 kW without degrading the beam in the rest of the ring. Here, simulation results for a ring-FEL as a EUVL source are described.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2016

Physics design of the in-vessel collection optics for the ITER electron cyclotron emission diagnostic

Measurement of the electron cyclotron emission (ECE) is one of the primary diagnostics for electron temperature in ITER. In-vessel, in-vacuum, and quasi-optical antennas capture sufficient ECE to achieve large signal to noise with microsecond temporal resolution and high spatial resolution while maintaining polarization fidelity. Two similar systems are required. One views the plasma radially. The other is an oblique view. Both views can be used to measure the electron temperature, while the oblique is also sensitive to non-thermal distortion in the bulk electron distribution. The in-vacuum optics for both systems are subject to degradation as they have a direct view of the ITER plasma and will not be accessible for cleaning or replacement for extended periods. Blackbody radiation sources are provided for in situ calibration.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Directional radiation detectors

Directional radiation detectors and systems, methods, and computer-readable media for using directional radiation detectors to locate a radiation source are provided herein. A directional radiation detector includes a radiation sensor. A radiation attenuator partially surrounds the radiation sensor and defines an aperture through which incident radiation is received by the radiation sensor. The aperture is positioned such that when incident radiation is received directly through the aperture and by the radiation sensor, a source of the incident radiation is located within a solid angle defined by the aperture. The radiation sensor senses at least one of alpha particles, beta particles, gamma particles, or neutrons.

36 MATERIALS SCIENCE↗
DOE OSTI2010

Identification Of Molecular Structures Of Normal And Pathological Human Breast Tissue Using Synchrotron Radiation

Scattering profiles of human breast tissues were measured by x-ray diffraction using a synchrotron radiation source in order to identify their structural features at molecular level (0.70{<=}q{<=}70.55 nm{sup -1}). Several parameters were extracted from these scattering profiles and statistically assessed using discriminant analysis. From this analysis, only the ratio between the peak intensities at q = 19.8 nm{sup -1} and at q = 13.9 nm{sup -1}, as well as the FWHM were statistically significant and allowed distinguishing the human breast tissues with high accuracy, mainly for benign samples where it was found values of sensitivity and specificity of 100%.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Photoionization of Ne Atoms and Ne{sup +} Ions Near the K Edge: PrecisionSpectroscopy and Absolute Cross-sections

Single, double, and triple photoionization of Ne{sup +} ions by single photons have been investigated at the synchrotron radiation source PETRA III in Hamburg, Germany. Absolute cross-sections were measured by employing the photon–ion merged-beams technique. Photon energies were between about 840 and 930 eV, covering the range from the lowest-energy resonances associated with the excitation of one single K-shell electron up to double excitations involving one K- and one L-shell electron, well beyond the K-shell ionization threshold. Also, photoionization of neutral Ne was investigated just below the K edge. The chosen photon energy bandwidths were between 32 and 500 meV, facilitating the determination of natural line widths. The uncertainty of the energy scale is estimated to be 0.2 eV. For comparison with existing theoretical calculations, astrophysically relevant photoabsorption cross-sections were inferred by summing the measured partial ionization channels. Discussion of the observed resonances in the different final ionization channels reveals the presence of complex Auger-decay mechanisms. The ejection of three electrons from the lowest K-shell-excited Ne{sup +}(1s2s{sup 2}2p{sup 62}S{sub 1/2}) level, for example, requires cooperative interaction of at least four electrons.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2010

TEMPO: a New Insertion Device Beamline at SOLEIL for Time Resolved Photoelectron Spectroscopy Experiments on Solids and Interfaces

A new insertion device beamline is now operational on straight section 8 at the SOLEIL synchrotron radiation source in France. The beamline and the experimental station were developed to optimize the study of the dynamics of electronic and magnetic properties of materials. Here we present the main technical characteristics of the installation and the general principles behind them. The source is composed of two APPLE II type insertion devices. The monochromator with plane gratings and spherical mirrors is working in the energy range 40-1500 eV. It is equipped with VLS, VGD gratings to allow the user optimization of flux or higher harmonics rejection. The observed resonance structures measured in gas phase enable us to determine the available energy resolution: a resolving power higher than 10000 is obtained at the Ar 2p, N 1s and Ne K-edges when using all the optical elements at full aperture. The total flux as a function of the measured photon energy and the characterization of the focal spot size complete the beamline characterization.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Conceptual design of a three-pole wiggler for the APS upgrade

The current design of the Advanced Photon Source Upgrade (APS-U) project is a multi-bend achromat (MBA) lattice, which incorporates three-pole wigglers as radiation sources for the bending magnet beamlines. They are located in the short section between the M4 dipole and Q8 quadrupole magnets. Due to space constraints, a hybrid permanent magnet design is necessary to provide the required magnetic field strength. A three-pole wiggler with a flat peak field profile along the beam axis was designed to enhance the photon flux and flatten the transverse flux density distributions. The magnetic peak field at the center pole reached 1.08 Tesla for a magnetic gap of 26 mm. The maximum power density, integrated over all vertical angles, is 3.1 W/mm{sup 2}, which is substantially higher than that of the existing bending magnets at the APS (0.86 W/mm{sup 2}). Detailed designs of the three-pole wiggler is presented, including calculated spectral-angular flux distributions.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Intense terahertz radiation from relativistic laser–plasma interactions

The development of tabletop intense terahertz (THz) radiation sources is extremely important for THz science and applications. This study presents our measurements of intense THz radiation from relativistic laser–plasma interactions under different experimental conditions. Several THz generation mechanisms have been proposed and investigated, including coherent transition radiation (CTR) emitted by fast electrons from the target rear surface, transient current radiation at the front of the target, and mode conversion from electron plasma waves (EPWs) to THz waves. Finally, the results indicate that relativistic laser plasma is a promising driver of intense THz radiation sources.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1970

Hazards from High Intensity Lamps and Arcs

The principal occupational health problem generally associated with high intensity arc lamps results from exposure of the eye and skin to ultraviolet radiation. Occasionally, the chorioretinal burns are of concern. The eye is generally more susceptible than the skin to injury from high intensity optical radiation sources whether ultraviolet, visible or infrared. Recent developments in technology have shown that some high intensity optical radiation sources which have output parameters greatly different from those encountered in the natural environment present a serious chorioretinal burn hazard.

Sliney, D. H.↗
DOE OSTI2011

Optimization of the Coherent Intensity from Multi-Segment Undulators by Phase Matching

The use of inline insertion devices at third-generation synchrotron radiation sources can result in destructive interference effects if the relative phase between the devices is not properly adjusted. The destructive interference can strongly affect the emission spectrum and coherent wavefront of a compound insertion device. We simulate the photon source generated by a dual-inline elliptically polarizing undulator (EPU) situated in a low-{beta} straight section of the planned NSLS-II storage ring and show that a magnetic chicane with adjustable field integral can be used to phase-match the devices. Furthermore, we show that the maximum coherent intensity is delivered by a focusing x-ray beamline if the chicane is adjusted to phase-match the off-axis and red-shifted radiation. Such a system will be installed at the coherent soft x-ray (CSX) beamline of the NSLS-II in order to provide the highest possible coherent flux for coherent soft x-ray scattering experiments.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2010

Wafer characteristics via reflectometry

Various exemplary methods (800, 900, 1000, 1100) are directed to determining wafer thickness and/or wafer surface characteristics. An exemplary method (900) includes measuring reflectance of a wafer and comparing the measured reflectance to a calculated reflectance or a reflectance stored in a database. Another exemplary method (800) includes positioning a wafer on a reflecting support to extend a reflectance range. An exemplary device (200) has an input (210), analysis modules (222-228) and optionally a database (230). Various exemplary reflectometer chambers (1300, 1400) include radiation sources positioned at a first altitudinal angle (1308, 1408) and at a second altitudinal angle (1312, 1412). An exemplary method includes selecting radiation sources positioned at various altitudinal angles. An exemplary element (1650, 1850) includes a first aperture (1654, 1854) and a second aperture (1658, 1858) that can transmit reflected radiation to a fiber and an imager, respectfully.

Sopori, Bhushan L↗
DOE OSTI2015

Special Analysis for the Disposal of the Oak Ridge National Laboratory General Radioactive Sources Waste Stream at the Area 5 Radioactive Waste Management Site, Nevada National Security Site, Nye County, Nevada

This special analysis (SA) evaluates whether the Oak Ridge National Laboratory (ORNL) General Radioactive Sources waste stream (ORNLSOURCES01, Revision 3) is suitable for disposal by shallow land burial (SLB) at the Area 5 Radioactive Waste Management Site (RWMS) at the Nevada National Security Site (NNSS). The ORNL General Radioactive Sources waste stream consists of sealed sources and solid radioactive sources that are no longer needed (ORNL 2015). The ORNL General Radioactive Sources waste stream required a special analysis because 26 radionuclides exceeded the NNSS Waste Acceptance Criteria (WAC) Action Levels (U.S. Department of Energy, National Nuclear Security Administration Nevada Field Office [NNSA/NFO] 2015). However, review of the generator’s method to calculate waste concentration indicates that the concentrations are significantly overestimated. Waste concentrations are recalculated in this analysis using a list of individual sources provided by the generator. One radionuclide, radium-226 (226Ra), still exceeds its action level and a Special Analysis (SA) is required. The results indicate that all performance objectives can be met with disposal of the ORNL General Radioactive Sources in a SLB trench. Addition of the ORNL General Radioactive Sources inventory slightly increases the 222Rn flux density. The maximum mean and 95th percentile flux density remain less than the performance objective throughout the compliance period. The ORNL General Radioactive Sources waste stream had no significant effect on the maximum mean and 95th percentile for all other performance assessment results. The ORNL General Radioactive Sources waste stream is suitable for disposal by SLB at the Area 5 RWMS. However, because the activity concentrations on the waste profile sheet are significantly overestimated, approval of the sheet could potentially allow the disposal of high activity radiation sources. To ensure the generator does not include large radiation sources in its waste stream, a control is recommended on the maximum individual source activity from this generator.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗