Broadening of Diffraction Peak Widths and Temperature Nonuniformity During Flash Experiments
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Materials Science↗
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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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Comparison of surface vacuum ultraviolet emissions with resonance level number densities. I. Argon plasmas
Vacuum ultraviolet (VUV) photons emitted from excited atomic states are ubiquitous in material processing plasmas. The highly energetic photons can induce surface damage by driving surface reactions, disordering surface regions, and affecting bonds in the bulk material. In argon plasmas, the VUV emissions are due to the decay of the 1s{sub 4} and 1s{sub 2} principal resonance levels with emission wavelengths of 104.8 and 106.7 nm, respectively. The authors have measured the number densities of atoms in the two resonance levels using both white light optical absorption spectroscopy and radiation-trapping induced changes in the 3p{sup 5}4p→3p{sup 5}4s branching fractions measured via visible/near-infrared optical emission spectroscopy in an argon inductively coupled plasma as a function of both pressure and power. An emission model that takes into account radiation trapping was used to calculate the VUV emission rate. The model results were compared to experimental measurements made with a National Institute of Standards and Technology-calibrated VUV photodiode. The photodiode and model results are in generally good accord and reveal a strong dependence on the neutral gas temperature.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Sci-Sat AM: Radiation Dosimetry and Practical Therapy Solutions - 03: Energy dependence of a clinical probe-format calorimeter and its pertinence to absolute photon and electron beam dosimetry
Purpose: To evaluate the intrinsic and absorbed-dose energy dependence of a small-scale graphite calorimeter probe (GPC) developed for use as a routine clinical dosimeter. The influence of charge deposition on the response of the GPC was also assessed by performing absolute dosimetry in clinical linac-based electron beams. Methods: Intrinsic energy dependence was determined by performing constant-temperature calorimetry dose measurements in a water-equivalent solid phantom, under otherwise reference conditions, in five high-energy photon (63.5 < %dd(10){sub X} < 76.3), and five electron (2.3 cm < R{sub 50} < 8.3 cm) beams. Reference dosimetry was performed for all beams in question using an Exradin A19 ion chamber with a calibration traceable to national standards. The absorbed-dose component of the overall energy dependence was calculated using the EGSnrc egs-chamber user code. Results: A total of 72 measurements were performed with the GPC, resulting in a standard error on the mean absorbed dose of better than 0.3 % for all ten beams. For both the photon and electron beams, no statistically-significant energy dependence was observed experimentally. Peak-to-peak, variations in the relative response of the GPC across all beam qualities of a given radiation type were on the order of 1 %. No effects, either transient or permanent, were attributable to the charge deposited by the electron beams. Conclusions: The GPC’s apparent energy-independence, combined with its well-established linearity and dose rate independence, make it a potentially useful dosimetry system capable measuring photon and electron doses in absolute terms at the clinical level.
61 RADIATION PROTECTION AND DOSIMETRY↗
Development of direct injection/ionization mass spectrometry methods for whole molecule characterization
Determining uranium isotopic and concentration information from environmental samples typically involves extensive chemical and physical processing prior to analysis. Harsh sample preparation results in the loss of the original uranium chemical speciation (i.e. what the uranium was bonded to/with when found in the environment) as well as the mixing of anthropogenic uranium with background material contained within the collection media (e.g. a swipe or soil). The objective of this work is to adapt a bioanalytical mass spectrometry technology called paper spray ionization mass spectrometry for the rapid analysis of intact uranium complexes. Soft ionization facilitates detection of whole molecule uranyl complexes including uranyl acetate, uranyl nitrate, and uranyl-tributylphosphate complex. Cotton swipe samples doped with a multi-element standard containing μg levels of U, Bi, Pb, Cd, Fe, and Zn were directly analyzed without purification, representing a major improvement over existing methods. Uranium quantitation is demonstrated using internal standards to obtain linear calibration curves. Limits of detection were determined to be approximately 100 ng for UO 2 and uranyl acetate through measurement of ppb level solutions. The development and qualification of PSI-MS techniques could lead to significant safeguards-related cost reduction and timeliness by facilitating the triage and queueing of swipe samples for more sensitive and time-consuming analyses.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Ta compressibility to 20+ Mbar
Developing techniques for experimentally constraining equation of state (EOS) models for important programmatic materials under extreme conditions is vital for advancing our modeling and predictive capabilities. Tantalum is a frequently used standard material for both calibration and testing, and this report describes our work to both measure Ta compressibility to very high pressures and densities using the Ramp Compression Equation of State platform on the National Ignition Facility (NIF). Using a series of seven shots, increasing in peak pressure with each shot, we have made absolute measurements of the compressibility of Ta along the ramp compression path up to 2.3 TPa. Previous experimental measurements constrained the cold compressibility up to ~400 GPa, and there is a spread in the EOS models above that pressure. To improve communication and collaboration between the experimental team and the EOS development group, these new data, along with other experimental and theoretical constraints, were used to develop a Ta equation of state table, M73000. This report first describes the experimental measurements made at the NIF, and then discusses the construction of the EOS model. The ramp compression data can be found in tabular form in Appendix A. Appendix B contains some additional experimental details. In Appendix C we include some additional details on the EOS modeling. At the end of this document, we have attached a detailed report on the NIF ramp compression platform itself and in the main text referenced specific sections for additional details.
36 MATERIALS SCIENCE↗
Carbon, Nitrogen, and Sulfur Analysis of the Cetama Viognier Standard Reference Material
The Viognier sample was analyzed for C, N, and S concentrations and stable isotope compositions using an Elementar Vario Isotope Cube Elemental Analyzer (EA) that is coupled to an IsoPrime PrecisION IRMS. Powder samples were placed in tin capsules and then loaded onto a rotary autosampler. The autosampler dropped samples into the EA, and samples were combusted at 1175 °C over tungsten oxide in a continuous stream of helium carrier gas. A pulse of oxygen is added to the gas stream resulting in flash combustion of the tin capsule containing the sample, which raises the reaction temperature to approximately 1800 °C for a few seconds. The combustion reaction produces SO 2 , N 2 and CO 2 from any sulfur, nitrogen and carbon present in the sample. The resulting gases were then passed through a reduced copper reactor that was heated to 850 °C, to reduce NO x to N 2 , reduce SO 3 to SO 2 , and trap any volatile halogen compounds on silver wool. Following water removal using an adsorption tube, the N 2 , CO 2 , and SO 2 analyte gases were separated and purified using purge-trap columns. The purified gases were then carried through a thermal conductivity detector. The detector signal was passed to software that calculated elemental abundances based on integrated peak areas. The sample gases were then passed to the IRMS and stable isotope ratios were measured. Raw sample peak areas were corrected by subtracting the average peak area from blanks consisting of empty tin capsules run using the same EA analysis method. Blanks were also run following each replicate to verify that all the material was combusted. The Viognier sample was analyzed in triplicate on two days (target sample masses: 30, 60 and 90 mg). The following standards were analyzed to calibrate EA-IRMS measurements: IAEA-C6, USGS-40, USGS-41, IAEA-S1, and IAEA-S2.
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
Applications of Alternate Actinide Calibration on Inductively Coupled Plasma Mass Spectrometry Analysis of H-Canyon Highly Enriched Uranium Legacy Material at the Savannah River Site
Alternate Actinide Calibration is beneficial for calibration using lower activity standards • ICP-MS and ICP-OES are valid complementary methods for U analysis • Recently procured Agilent 8900 ICP-QQQ-MS in radiological buffer area –installation in progress • Helium (kinetic energy discrimination) can be used for reducing polyatomic interferences • Installing hydrogen and oxygen (reaction gases) on 8900 ICP-MS systems to improve LODs of several challenging analytes
Jones, Mark A.↗
GEANT4 code for DANCE with NEUANCE detector-response simulations
A new GEANT4 model for DANCE with NEUANCE has been developed to account for the change in the DANCE configuration when NEUANCE is installed. In this model, the energy resolution and the shape of the threshold of the individual DANCE detectors are used as an input to provide realistic representation of the measured γ-ray spectra. In addition, the distance from each detector to the target is defined in an input file as well as the physical presence of the a detector in the DANCE and NEUANCE arrays. The azimuthal angle of NEUANCE is also an external parameter to be tuned to represent the measurement. Simulated spectra are compared with measurements with standard γ-ray calibrated sources.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Identifying the Accuracy of Surface Roughness for Metal Additive Manufacturing Parts Captured with Computed Tomography Scanning
Conventional surface roughness measurement techniques require direct access to internal surfaces, often necessitating destructive sectioning of test articles. Computed tomography (CT) offers a non-destructive alternative for internal surface characterization, but its application in metrology remains unstandardized and sensitive to machine resolution and operator technique. This study investigates the feasibility of using CT scanning to quantify areal surface roughness in metal AM heat exchanger tubes with three distinct internal geometries: ribbed, discrete W, and featureless. CT-derived surface parameters were extracted using custom Python scripts and compared to measurements obtained from a focus variation microscope calibrated against a known standard. Results show that CT-based roughness measurements closely matched microscope values for the discrete W specimen, deviations between CT and microscope measurements were minimal—less than 1 µm—indicating reliable reconstruction. In contrast, the ribbed and featureless specimens, with lower roughness values showed greater discrepancies. The findings suggest that CT scanning can be a viable non-destructive metrology tool for AM parts with surface roughness above approximately 8 µm. For smoother surfaces, current CT capabilities may not provide sufficient accuracy, highlighting the need for resolution-aware workflows and further standardization in CT-based surface metrology.
36 MATERIALS SCIENCE↗
System-Level Design Studies for Large Rotors
We examine the effect of rotor design choices on the power capture and structural loading of each major wind turbine component. A steady-state, harmonic model derived from simulations using the NREL aeroelastic code FAST is developed to reduce computational expense while evaluating design trade-offs for rotors with radii greater than 100 m. Design studies are performed, which focus on blade aerodynamic and structural parameters as well as different hub configurations and nacelle placements atop the tower. The effects of tower design and closed-loop control are also analyzed. Design loads are calculated according to the IEC design standards and used to calibrate the harmonic model and quantify uncertainty. Our design studies highlight both industry trends and innovative designs: we progress from a conventional, upwind, 3-bladed rotor, to a rotor with longer, more slender blades that is downwind and 2-bladed. For a 13 MW design, we show that increasing the blade length by 25 m while decreasing the induction factor of the rotor increases annual energy capture by 11% while constraining peak blade loads. A downwind, 2-bladed rotor design is analyzed, with a focus on its ability to reduce peak blade loads by 10% per 5 deg. of cone angle, and also reduce total blade mass. However, when compared to conventional, 3-bladed, upwind designs, the peak main bearing load of the up-scaled, downwind, 2-bladed rotor is increased by 280%. Optimized teeter configurations and individual pitch control can reduce non-rotating damage equivalent loads by 45% and 22%, respectively, compared with fixed-hub designs.
17 WIND ENERGY↗
Development of a stable ultraviolet source and techniques for accurate radiometry annual summary report, jan. 1 - dec. 31, 1964
Argon arc stable source of high ultraviolet radiation and high accuracy spectroradiometer for calibration of spectral radiation standards
RADIATION SOURCE↗
Interim solar cell testing procedures for terrestrial applications
An interim draft of a set of test procedures, developed by NASA/ERDA, for the manufacture of solar cells is introduced. This version includes procedures for cell testing both outdoors in natural sunlight and indoors in simulated sunlight, a description of the necessary apparatus and equipment, the calibration and use of standard solar cells, and a proposed air-mass-two (AM2) solar spectrum.
Brandhorst, H.↗
Angiocardiography - Past and present
Angiocardiography is defined as an X-ray procedure which uses an intravascularly injected contrast material for visualization of the internal anatomy of the heart and great vessels. Past and present efforts in angiocardiography technology and methodology are reviewed, with special emphasis on qualitative and quantitative measurements of heart and vessel geometry. One of the more recent applications of angiographic image analysis has been for pattern recognition of margin motions over a cardiac cycle, termed contourography. Angiocardiography will continue to serve, as it has served in the past, as the principal standard of reference for calibration and/or comparison of newer methods for determining volume or dimensional change, depending on further technologic advances in X-ray equipment and means for displaying computer-processed information.
Sandler, H.↗
A laser based characterization facility for silicon photocell studies
A computer controlled laser based characterization facility used for detailed studies of silicon photodetectors and spectral response measurement on silicon solar cell is described. The power in the laser beam is measured with respect to electrical standards using an electrically calibrated pyroelectric radiometer.
Geist, J.↗
Compact far ultraviolet emission source with rich spectral emission 1150-3100 A
The article describes a compact hollow Pt cathode emission source for the far UV, developed for use as a high-resolution wavelength standard in laboratory work or on spacecraft (specifically, the NASA International UV Explorer - IUE). The source is small, rugged, lightweight, spectrally rich, bright in the 1150-3200 A region, features long service life, low operating voltage, and lower power drain, and stably emits a large number of very sharp lines with a spectrum lending itself to projection onto the focal plane of a spectrograph. The source has successfully passed exacting environmental tests, and serves as a transfer standard for absolute sensitivity calibration of spectrometric instruments.
Mount, G. H.↗
Application of airborne infrared technology to monitor building heat loss
The application of airborne infrared technology to the requirements for energy conservation in buildings was studied. Quantitative airborne data of the City of Ypsilanti, Michigan, were collected and processed to identify roof temperatures. A thermal scanner was flown at an altitude of 1,200 feet with two thermal bands 8.2-9.3 micrometers and 10.4-12.5 micrometers recorded by an analog system. Calibration was achieved by standard hot and cold plates. Using a thermal model to interpret ceiling insulation status, environmental factors were found to influence the relation between roof temperature and insulation. These include interior and sky temperatures, roofing materials, and the pitch and orientation of the roof. A follow-up mail survey established the ability to identify insulated and uninsulated houses from the airborne infrared data.
Tanis, F. J.↗
Work function determination of promising material for thermionic converters
The work done to fabricate Marchuk plasma discharge tubes for measurement of the cesiated emission of lanthanum hexaboride and thoriated tungsten electrodes is described. A photon counting pyrometer was completed and is to be calibrated with a gold standard.
Jacobs, M. H.↗
Comparison of modern icing cloud instruments
Intercomparison tests with Particle Measuring Systems (PMS) were conducted. Cloud liquid water content (LWC) measurements were also taken with a Johnson and Williams (JW) hot-wire device and an icing rate device (Leigh IDS). Tests include varying cloud LWC (0.5 to 5 au gm), cloud median volume diameter (MVD) (15 to 26 microns), temperature (-29 to 20 C), and air speeds (50 to 285 mph). Comparisons were based upon evaluating probe estimates of cloud LWC and median volume diameter for given tunnel settings. Variations of plus or minus 10% and plus or minus 5% in LWC and MVD, respectively, were determined of spray clouds between test made at given tunnel settings (fixed LWC, MVD, and air speed) indicating cloud conditions were highly reproducible. Although LWC measurements from JW and Leigh devices were consistent with tunnel values, individual probe measurements either consistently over or underestimated tunnel values by factors ranging from about 0.2 to 2. Range amounted to a factor of 6 differences between LWC estimates of probes for given cloud conditions. For given cloud conditions, estimates of cloud MVD between probes were within plus or minus 3 microns and 93% of the test cases. Measurements overestimated tunnel values in the range between 10 to 20 microns. The need for improving currently used calibration procedures was indicated. Establishment of test facility (or facilities) such as an icing tunnel where instruments can be calibrated against known cloud standards would be a logical choice.
Takeuchi, D. M.↗