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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Measurement of accreted helium ion velocity using Doppler spectroscopy in the CTIX compact-toroid plasma accelerator

A compact-toroid (CT) accelerator is a device for the production of plasma bodies which contain a relatively strong internal magnetic field, which permits the plasma body to withstand large forces of acceleration while retaining its magnetic field structure. Typically, the CT occupies an annular region between inner and outer radii, defined by coaxial inner and outer electrodes, across which a large electric potential is applied. The internal magnetic fields of the CT contain both a toroidal and poloidal component, as shown in Fig. 1(a). These fields are typically of comparable magnitude. Because of the effective rigidity provided by internal magnetic fields, the CT can be accelerated to high velocities in short distances. Since internal fields increase in proportion to accelerating magnetic field, there is no strength at which the accelerating magnetic fields overcome the internal field (blow-by). Because of this, the kinetic energy density of CTs can be made to exceed the energy density of magnetic fields typical of plasma containment devices such as tokamaks. CTs have the potential to be launched into the interior of such devices for either delivering fuel (typically deuterium or hydrogen), or to deliver particles of high atomic number (high-Z). An important application of high-Z CT injection into tokamaks is to aid in plasma quenching by radiation, to mitigate the effects of plasma disruptions and prevent damage to the plasma confinement device. In addition, high-Z CTs may be used as sources of kinetic energy density for plasma-compression experiments. In this case, the use of plasma species of high atomic number is also desirable, since kinetic energy density is proportional to atomic number for given CT velocity and electron density gas puffing.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1977

Multiple-laser-energy detection system

Technique monitors energy output of each of four sequentially-pulsed dye lasers for the Airborne LIDAR Oceanographic Probing Experiment system. Fiber optics attached to output mirrors transmit optical signal proportional to output energy.

Jarrett, O., Jr.↗
DOE OSTI2022

A comparison of building system parameters between affordable and market-rate housing in New York City

Low-income households in the United States experience higher than average energy burdens (defined as the proportion of household income spent on energy utilities), and many of these households struggle to simultaneously pay for rent, energy, and basic household necessities. The analysis presented here in this study examines whether the underlying characteristics of buildings and their energy systems could contribute to this disparity for affordable housing residents in New York City. It combines an energy audit dataset of 7,328 multifamily buildings with a database of properties receiving local, state, or federal housing subsidies. The results of this analysis indicate that the building-level installed equipment in large (greater than 50,000 square feet) affordable housing buildings in New York City is more efficient than that in market-rate buildings, but this trend largely disappears when considering overall building characteristics, such as location, size, or age. Significant differences in the types of systems installed in affordable and market-rate housing are also observed, as well as the types of energy efficiency recommendations made by energy auditors. However, these latter data were not normalized by building system characteristics, as that analysis is much more difficult to interpret for categorical data such as heating system type. These findings indicate that retrofit policies and building performance standards focused on affordable housing will likely need to account for underlying differences in building characteristics between affordable and market-rate housing to achieve intended impacts.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2015

Lithium ionic mobility study in xLi{sub 2}CO{sub 3}-yLiI (x = 95-70, y = 5-30 wt.%) solid electrolyte by impedance spectroscopy technique

A detailed systematic study on the effects of different amount (wt.%) of LiI addition on the electrical conductivity and dielectric behavior of the xLi{sub 2}CO{sub 3}-xLiI (x = 95-70, y = 5-30 wt.%) electrolyte system was carried out. The samples with different compositions were prepared and ground by mechanical milling method. The electrical and dielectric properties of the samples over a range of frequency (50Hz – 1MHz) were investigated by deploying electrical impedance spectroscopy (EIS) technique in a series of temperature set (298–373K). Normally, Li{sub 2}CO{sub 3} itself shows a very low electrical conductivity (10{sup −5} Scm{sup −1}). However, the electrical conductivity of the system was found to be increased (10{sup −3} Scm{sup −1}) as the lithium salt (LiI) were introduced to the system. The dielectric analysis displayed that the activation energy was inversely proportional to the increment of LiI (wt.%). As the electrical conductivity reached their maximum value (4.63 × 10{sup −3} Scm{sup −1}) at the 20 wt.% of LiI, the activation energy was dropped to the minimum (0.1 eV). The electrical conductivity increases with the temperature (298 – 373K) indicate that the system obeys Arrhenius law.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Measurement of diagnostic neutral beam parameters on J-TEXT

A Doppler frequency shift spectrum (DFSS) system composed of two spectrometers has been developed for the joint Texas experimental tokamak to measure diagnostic neutral beam parameters including the beam energy fractions, intensity distributions, and divergences. The beam energy fractions are derived from measurements of H-alpha (Hα) emission using collisional excitation cross sections. The beam intensity distributions are obtained using an 11-channel measurement with a reconstruction technique. The beam divergences are obtained from spectrum broadening and geometric calculations. The results of preliminary investigations indicate that the DFSS system works well and can be used to obtain all of these parameters simultaneously. According to the preliminary experiment, the one-third energy fraction has the largest proportion (about 45%) of the beam energy and the full energy fraction is about 10%. The beam diameter is about 8.1 cm at a distance of 2.04 m from the accelerator. The beam divergence angle is about 3.3°. The current beam parameters are insufficient for charge-exchange measurements.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Characterizing the Gravitational Wave Signal from Core-collapse Supernovae

We study the gravitational wave (GW) signal from eight new 3D core-collapse supernova simulations. We show that the signal is dominated by f - and g -mode oscillations of the protoneutron star (PNS) and its frequency evolution encodes the contraction rate of the latter, which, in turn, is known to depend on the star's mass, on the equation of state, and on transport properties in warm nuclear matter. A lower-frequency component of the signal, associated with the standing accretion shock instability, is found in only one of our models. Lastly, we show that the energy radiated in GWs is proportional to the amount of turbulent energy accreted by the PNS.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2006

Comparisons of Integrated Radiation Transport Models with Microdosimetry Data in Spaceflight

Astronauts are exposed to galactic cosmic rays (GCR), trapped protons, and possible solar particle events (SPE) during spaceflight. For such complicated mixtures of radiation types and kinetic energies, tissue equivalent proportional counters (TEPC's) represent a simple time-dependent approach for radiation monitoring. Of interest in radiation protection is the average quality factor of a radiation field defined as a function of linear energy transfer, LET, Q(sub ave)(LET). However TEPC's measure the average quality factors as a function of lineal energy (y), Q(sub ave)(y) defined as the average energy deposition in a volume divided by the average chord length of the volume. Lineal energy, y deviates from LET due to energy straggling, delta-ray escape or entry, and nuclear fragments produced in the detector. Using integrated space radiation models that includes the transport code HZETRN/BRYNTRN, the quantum nuclear interaction model, QMSFRG, and results from Monte-Carlo track simulations of TEPC's response to ions, we consider comparisons of model calculations to TEPC results from NASA missions in low Earth orbit and make predictions for lunar and Mars missions. Good agreement between the model and measured spectra from past NASA missions is found. A finding of this work is that TEPC's values for trapped or solar protons of Q(sub ave)(y) range from 1.9-2.5, overestimating Q(sub ave)(LET), which ranges from 1.4-1.6 with both quantities increasing with shielding depth due to nuclear secondaries Comparisons for the complete GCR spectra show that Q(sub ave)(LET) for GCR is approximately 3.5-4.5, while TEPC's measure 2.9-3.4 for Q(sub ave)(y) with the GCR values decreasing with depth as heavy ions are absorbed in shielding material. Our results support the use of TEPC's for space radiation environmental monitoring when computational analysis is used for proper data interpretation.

Cucinotta, Francis A.↗
DOE OSTI2017

One-loop free energy of tensionless type IIB string in AdS 5 ×S 5

Considering the zero ’t Hooft coupling limit of $\mathcal{N}$=4 super-Yang-Mills theory, the exact spectrum of all single-trace operators can be accessed in terms of the underlying so (2, 4) character. This makes it possible in turn to compute the one-loop free energy of the tensionless type IIB string theory in AdS 5 ×S 5 background, with help of the recently developed method of character integral representation of zeta function (CIRZ) . We calcu-late first the one-loop free energy of the string states in the ( p - 1)-th Regge trajectory and find the result to be p times the free energy of a single $\mathcal{N}$=4 Maxwell multiplet. The full one-loop free energy is hence proportional to the divergent series $\sum^{∞}_{p=2}p$. The divergence arises as a result of interrupting the regularization procedure in an intermediate stage. With a reorganization of states, we extract the finite part of free energy after summing over the Regge trajectories. This way gives us a finite result which is minus of the free energy of the $\mathcal{N}$=4 multiplet. Hence, this bulk one-loop result matches the -1 term in the N 2 - 1 factor of the boundary result.

1/N expansion↗
DOE OSTI2011

Correlation between relaxations and plastic deformation, and elastic model of flow in metallic glasses and glass-forming liquids

We study the similarity and correlations between relaxations and plastic deformation in metallic glasses (MGs) and MG-forming liquids. It is shown that the microscope plastic events, the initiation and formation of shear bands, and the mechanical yield in MGs where the atomic sites are topologically unstable induced by applied stress, can be treated as the glass to supercooled liquid state transition induced by external shear stress. On the other hand, the glass transition, the primary and secondary relaxations, plastic deformation and yield can be attributed to the free volume increase induced flow, and the flow can be modeled as the activated hopping between the inherent states in the potential energy landscape. We then propose an extended elastic model to describe the flow based on the energy landscape theory. That is, the flow activation energy density is linear proportional to the instantaneous elastic moduli, and the activation energy density {rho}{sub E} is determined to be a simple expression of {rho}{sub E}=(10/11)G+(1/11)K. The model indicates that both shear and bulk moduli are critical parameters accounting for both the homogeneous and inhomogeneous flows in MGs and MG-forming liquids. The elastic model is experimentally certified. We show that the elastic perspectives offers a simple scenario for the flow in MGs and MG-forming liquids and are suggestive for understanding the glass transition, plastic deformation, and nature and characteristics of MGs.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Nonlinear light-output calibration of the oxygenated xylene scintillators used in OMEGA neutron time-of-flight spectrometers

Neutron time-of-flight (nTOF) spectrometers are essential instruments for measuring and evaluating the performance of inertial confinement fusion implosions. The neutron spectrometers utilized for the OMEGA laser include two liquid-based scintillators, each consisting of a large volume filled with xylene that is coupled to four photomultiplier tubes. Analysis of the signal from these detectors requires detailed knowledge of the scintillator’s light output, which is needed to fit the nTOF spectrum, from which the neutron energy spectrum is informed. The light output is nonlinearly proportional to the neutron energy, which, in turn, affects the interpretation of the neutron energy spectrum from a TOF signal. A recent campaign on OMEGA was performed to calibrate the xylene detectors and infer the shape of the light-output curve. The campaign utilized materials with increasing Z placed in the OMEGA target chamber to initiate scattering events with the 14 MeV fusion neutrons. This process leads to the production of backscatter neutrons of varying energies that appear as peaks in the nTOF data. Simulations using a neutron transport code were combined with the measured deuterium–tritium neutron yields to calculate the expected backscattered neutron yields from the well-known scattering cross sections of each material. Furthermore, the neutron-energy dependent light output of the scintillator inferred from the experiment is compared to the light-output curve simulated with a neutron transport code for the following neutron energies: 1.5, 2.5, 6, and 14 MeV.

47 OTHER INSTRUMENTATION↗
NASA NTRS1986

Electron-positron pair production by ultrarelativistic electrons in a soft photon field

The fully differential cross section for photon-electron pair production is integrated numerically over phase space. Results are obtained for the astrophysically interesting case in which the interaction between an ultrarelativistic electron and a soft photon results in electron-positron pair production. The positron spectrum is a function of the energies of both the photon and the electron, as well as the angle of interaction. It is found that the energy at which the positron distribution peaks is inversely proportional to the photon energy and independent of the electron energy. The positron spectrum is integrated once more over initial electron energies for a power-law energy distribution of primary electrons. The same procedure is repeated for the recoil particle; it is shown that the peak of the recoil energy distribution depends linearly on the energy of the primary electron. Finally, semianalytical expressions are obtained for the energy losses of the primary electrons.

Mastichiadis, A.↗
DOE OSTI2022

Designing polymeric membranes with coordination chemistry for high-precision ion separations

State-of-the-art polymeric membranes are unable to perform the high-precision ion separations needed for technologies essential to a circular economy and clean energy future. Coordinative interactions are a mechanism to increase sorption of a target species into a membrane, but the effects of these interactions on membrane permeability and selectivity are poorly understood. We use a multilayered polymer membrane to assess how ion-membrane binding energies affect membrane permeability of similarly sized cations: Cu 2+ , Ni 2+ , Zn 2+ , Co 2+ , and Mg 2+ . We report that metals with higher binding energy to iminodiacetate groups of the polymer more selectively permeate through the membrane in multisalt solutions than single-salt solutions. In contrast, weaker binding species are precluded from diffusing into the polymer membrane, which leads to passage proportional to binding energy and independent of membrane thickness. Our findings demonstrate that selectivity of polymeric membranes can markedly increase by tailoring ion-membrane binding energy and minimizing membrane thickness.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Lineal energy calibration of mini tissue-equivalent gas-proportional counters (TEPC)

Mini TEPCs are cylindrical gas proportional counters of 1 mm or less of sensitive volume diameter. The lineal energy calibration of these tiny counters can be performed with an external gamma-ray source. However, to do that, first a method to get a simple and precise spectral mark has to be found and then the keV/{mu}m value of this mark. A precise method (less than 1% of uncertainty) to identify this markis described here, and the lineal energy value of this mark has been measured for different simulated site sizes by using a {sup 137}Cs gamma source and a cylindrical TEPC equipped with a precision internal {sup 244}Cm alpha-particle source, and filled with propane-based tissue-equivalent gas mixture. Mini TEPCs can be calibrated in terms of lineal energy, by exposing them to {sup 137}Cesium sources, with an overall uncertainty of about 5%.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

Evaluation of a Fluorochlorozirconate Glass-Ceramic Storage Phosphor Plate for Gamma-Ray Computed Radiography

In this paper, a fluorochlorozirconate (FCZ) glass-ceramic containing orthorhombic barium chloride crystals doped with divalent europium was evaluated for use as a storage phosphor in gamma-ray imaging. X-ray diffraction and phosphorimetry of the glass-ceramic sample showed the presence of a significant amount of orthorhombic barium chloride crystals in the glass matrix. Transmission electron microscopy and scanning electron microscopy were used to identify crystal size, structure, and morphology. The size of the orthorhombic barium chloride crystals in the FCZ glass matrix was very large, ~0.5–0.7 μm, which can limit image resolution. The FCZ glass-ceramic sample was exposed to 1 MeV gamma rays to determine its photostimulated emission characteristics at high energies, which were found to be suitable for imaging applications. Test images were made at 2 MeV energies using gap and step wedge phantoms. Gaps as small as 101.6 μm in a 440 stainless steel phantom were imaged using the sample imaging plate. Analysis of an image created using a depleted uranium step wedge phantom showed that emission is proportional to incident energy at the sample and the estimated absorbed dose. Finally, the results showed that the sample imaging plate has potential for gamma-ray-computed radiography and dosimetry applications.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Constraining AGN feedback in massive ellipticals with south pole telescope measurements of the thermal Sunyaev–Zel’dovich effect

Energetic feedback due to active galactic nuclei (AGNs) is likely to play an important role in the observed anti-hierarchical trend in the evolution of galaxies, and yet the energy injected into the circumgalactic medium by this process is largely unknown. One promising approach to constrain this feedback is through measurements of spectral distortions in the cosmic microwave background due to the thermal Sunyaev–Zeldovich (tSZ) effect, whose magnitude is directly proportional to the energy input by AGNs. With current instruments, making such measurements requires stacking large numbers of objects to increase signal-to-noise. While one possible target for such stacks is AGNs themselves, these are relatively scarce sources that contain contaminating emission that complicates tSZ measurements. Here we adopt an alternative approach and co-add South Pole Telescope SZ (SPT-SZ) survey data around a large set of massive quiescent elliptical galaxies at z⩾0.5, which are much more numerous and less contaminated than active AGNs, yet are subject to the same feedback processes from the AGNs they hosted in the past. We use data from the Blanco Cosmology Survey and VISTA Hemisphere Survey to create a large catalog of galaxies split up into two redshift bins: one with 3394 galaxies at 0.5⩽z⩽1.0 and one with 924 galaxies at 1.0⩽z⩽1.5, with typical stellar masses of 1.5×10{sup 11}M{sub ⊙}. We then co-add the emission around these galaxies, resulting in a measured tSZ signal at 2.2σ significance for the lower redshift bin and a contaminating signal at 1.1σ for the higher redshift bin. To remove contamination due to dust emission, we use SPT-SZ source counts to model a contaminant source population in both the SPT-SZ bands and Planck high-frequency bands for a subset of 937 galaxies in the low-redshift bin and 240 galaxies in the high-redshift bin. This increases our detection to 3.6σ for low redshifts and 0.9σ for high redshifts. We find the mean angularly integrated Compton-y values to be 2.2{sub −0.7}{sup +0.9}×10{sup −7} Mpc{sup 2} for low redshifts and 1.7{sub −1.8}{sup +2.2}×10{sup −7} Mpc{sup 2} for high redshifts, corresponding to total thermal energies of 7.6{sub −2.3}{sup +3.0}×10{sup 60} erg and 6.0{sub −6.3}{sup +7.7}×10{sup 60} erg, respectively. These numbers are higher than expected from simple theoretical models that do not include AGN feedback, and serve as constraints that can be applied to current simulations of massive galaxy formation.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2004

Primary Mineralogical and Chemical Characteristics of the Major K/T and Late Eocene Impact Deposits

Three well-characterized, distal impact deposits at the WT boundary and in upper Eocene sediments serve as a baseline for understanding other proposed impact deposits. All contain abundant spherules, evidence of shock metamorphism, and the largest have significant extraterrestrial components (ETCs). The K/T and the Eocene cpx-spherule (cpxS) deposits are global - likely from the events that produced the 180 km Chicxulub and 100 km Popigai craters. The Eocene North American microtektite (NAM) deposit is regional and likely from the event that produced the 45 km Chesapeake Bay crater. These deposits all contain abundant spherules formed from both shock-melted target and mixtures of target and projectile in the ejecta plume. Spherules constitute most of the mass of the distal ejecta. K/T spherules in regional deposits around the Gulf of Mexico are from low-velocity, target-rich ejecta. These can be a few mm in size and form deposits 10s of cm thick. Globally deposited KIT spherules from the plume (typically a few hundred micron size) are both target- and projectile-rich. When well preserved, the global deposits are 3 mm thick. Eocene cpxS deposits are similar to distal K/T with both target- and projectile-rich varieties (Le., glassy microtektite, and cpx spherules). They are smaller on average than WT spherules, concentrated in the 125-250 micron and smaller fractions. They are invariably bioturbated, but the initial deposit was probably less than 1 mm thick. The NAM are composed entirely of target-rich glass. They are similar in size to the cpxS. Size is an important criterion for distal ejecta because droplet size in the impact plume is proportional to the energy of the impact. Both the JUT and cpxS deposits are characterized by well-defined ETCs, commonly measured by Ir. The total Ir deposited is about 55 ng per square cm in WT sediments, and about 11 ng for the cpxS layer. This 5/1 proportion in Ir is generally consistent with the approx.1.8/1 ratio in crater diameters. The NAM have no significant ETC. This may be a function of the smaller impact. It indicates there was no significant projectile-rich plume deposit.

Kyte, Frank T.↗
DOE OSTI2016

Low Z target switching to increase tumor endothelial cell dose enhancement during gold nanoparticle-aided radiation therapy

Purpose: Previous studies have introduced gold nanoparticles as vascular-disrupting agents during radiation therapy. Crucial to this concept is the low energy photon content of the therapy radiation beam. The authors introduce a new mode of delivery including a linear accelerator target that can toggle between low Z and high Z targets during beam delivery. In this study, the authors examine the potential increase in tumor blood vessel endothelial cell radiation dose enhancement with the low Z target. Methods: The authors use Monte Carlo methods to simulate delivery of three different clinical photon beams: (1) a 6 MV standard (Cu/W) beam, (2) a 6 MV flattening filter free (Cu/W), and (3) a 6 MV (carbon) beam. The photon energy spectra for each scenario are generated for depths in tissue-equivalent material: 2, 10, and 20 cm. The endothelial dose enhancement for each target and depth is calculated using a previously published analytic method. Results: It is found that the carbon target increases the proportion of low energy (<150 keV) photons at 10 cm depth to 28% from 8% for the 6 MV standard (Cu/W) beam. This nearly quadrupling of the low energy photon content incident on a gold nanoparticle results in 7.7 times the endothelial dose enhancement as a 6 MV standard (Cu/W) beam at this depth. Increased surface dose from the low Z target can be mitigated by well-spaced beam arrangements. Conclusions: By using the fast-switching target, one can modulate the photon beam during delivery, producing a customized photon energy spectrum for each specific situation.

61 RADIATION PROTECTION AND DOSIMETRY↗