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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Virginia precipitation scatter experiment: Experiment description

A year's statistical data were acquired for the purposed of refining existing coordination procedures for the sharing of common frequency allocations between terrestrial and space services. The measurement program was conducted between October 3, 1970 and October 2, 1971, to empirically determine the cumulative distributions of scattering cross section per unit volume of hydrometeors at heights up to 9 km above the surface and of rain rate at the surface. The measurements were made in southeastern Virginia using a bistatic, continuous-wave, vertically polarized radar system operating at S- and X-band frequencies and tipping-bucket rain gages. The bistatic radar system was configured to represent an interference situation between a radio-relay system and a space communication system Earth terminal; the results may be interpreted as measured distributions of transmission loss for interference due to rain. A description of the experiment and equipment is included.

Levine, E.↗
NASA NTRS1989

Miniature instrumentation for laser light scattering experiments

Traditional optical systems for photon correlation spectroscopy and laser anemometry have relied upon physically large and fairly expensive lasers, bulk-optics such as lenses of a few inches diameter, large mechanical mounts and carefully selected, fragile and bulky photon counting photomultiplier detectors. In some cases, experimental fluid dynamics at a desired position in a flow, perhaps deep inside complex machinery, is physically impossible or very difficult. Similar problems exist with photon correlation spectroscopy, e.g., remote and heterodyne experiments. Various optical and electro optical components were investigated and characterized with the aim of replacing existing photon correlation laser spectroscopy and anemometry techniques in miniaturized form, and with significant cost reduction. Very recently, a range of miniature, modular light scattering systems were constructed from little solid state optical and electro optical components, and experimentally verified measurement performance comparable to standard lab photon correlation spectroscopy and laser anemometry equipment.

Brown, Robert G. W.↗
NASA NTRS1975

Mariner 9 ultraviolet spectrometer experiment - Scattering properties of Hellas

A least-squares analysis of 709 Mariner 9 UV spectra obtained over Hellas from Revolution 140 to 214 (Jan. 22, 1972, to Feb. 28, 1972) showed the extinction optical depth of the atmosphere above Hellas to be 0.5 plus or minus 0.2. This is evidence of lingering dust in the Hellas basin. An atmospheric model, combining dust and Rayleigh scattering, was used to make an apparent pressure map of Hellas. Anomalously high pressures are interpreted as clouds developing over the southern part of Hellas near the time of autumnal equinox. The blue ratio (reflectance at 2680 A divided by reflectance at 3050 A) showed a 20% increase from Revolution 40 to Revolution 74, attributed to the decay of the dust storm. Thereafter, the blue ratio remained essentially constant through Revolution 214, which implies that the rate of clearing in Hellas was much slower than that planetwide.

Ajello, J. M.↗
NASA NTRS1994

ZENO: A Critical Fluid Light Scattering Experiment

The ZENO experiment flew on the STS-62, it is designed to verify intriguing, but previously untested, theories in fluid physics. These theories attempt to describe dramatic changes in the properties of fluids near the critical temperature at which the vapor and liquid forms co-exist.

Source record↗
DOE OSTI2024

Implicit neural representations for experimental steering of advanced experiments

Scattering measurements using electrons, neutrons, or photons are essential for obtaining microscopic insights into materials. However, limited facility availability and high-dimensional scattering data necessitate more efficient experimental steering techniques. Here, we report a machine learning method that guides scattering data collection and facilitates real-time estimation of model parameters, given a reliable forward model to simulate experimental signals. We employ implicit neural representations as efficient surrogates that link model parameters with simulated spectroscopies. This enables a Bayesian optimal experimental design framework to estimate the probability distributions of parameters from high-dimensional scattering data. We demonstrate the proposed method using inelastic neutron scattering with simulated and real experimental data, highlighting the method’s ability to provide real-time parameter estimation with quantified uncertainties and to deliver informed experimental guidance that reduces experimental time while maximizing scientific output. This approach paves the way for accelerated discoveries in condensed matter through scattering measurements.

36 MATERIALS SCIENCE↗
NASA NTRS1975

Requirements for space shuttle scatter radar experiments

The feasibility of carrying out scatter radar experiments on the space shuttle was analyzed. Design criteria considered were the required average transmitter power, frequency resolution, spatial resolution, and statistical accuracy. Experiments analyzed were measurement of the naturally enhanced plasma line and the ion component of the incoherent scatter spectrum, and the plasma line artificially enhanced by an intense HF radio wave. The ion component measurement does not appear feasible, while the other two appear reasonable for short ranges only.

Harker, K. J.↗
DOE OSTI2025

ESAC (EQ-SANS Assisting Chatbot): Application of large language models and retrieval-augmented generation for enhanced user experience at EQ-SANS

Neutron scattering experiments have played vital roles in exploring materials properties in the past decades. While user interfaces have been improved over time, neutron scattering experiments still require specific knowledge or training by an expert due to the complexity of such advanced instrumentation and the limited number of experiments each person may perform each year. This paper introduces an innovative chatbot application that leverages Large Language Models(LLM) and Retrieval-Augmented Generation (RAG) technologies to significantly enhance the user experience at the EQ-SANS, a small-angle neutron scattering instrument at the Spallation Neutron Source of Oak Ridge National Laboratory. Through a user-centric design approach, the EQ-SANS Assisting Chatbot (ESAC) serves as an interactive reference for users, thereby facilitating the use of the instrument by visiting scientists. By bridging the gap between the users of EQ-SANS and the control systems required to perform their experiments, the ESAC sets a new standard for interactive learning and support for the scientific community using large-scale scientific facilities.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS1978

Comparison of satellite self-contamination experiments and scattering return flux calculations

Gaseous emissions from a spacecraft modify the orbital environment and degrade the observations of distant radiation sources. These emissions also provide contamination fluxes induced by self-scattering and scattering with ambient particles. Experiments were carried out on the orbiting Atmosphere Explorer D satellite (AE-D) to verify the calculated return fluxes of a neon source. Known rates of neon were emitted in the direction of the velocity vector on command from the MRMU (molecular return measurement unit). At 250 km the neutral mass spectrometer indicated a total neon return flux of 0.0246 times the emitted flux. The calculated fraction was 0.0123, including 0.00914 for the ambient scatter and 0.00354 for the altitude-independent self-scatter. The pressure gages indicated pressures less than 7 microtorr at altitudes from 161 to 210 km. The maximum pressure for the 161-km orbit was calculated as 0.74 microtorr.

Scialdone, J. J.↗
NASA NTRS1976

Investigation of aerosol characteristics and their measurement

Various techniques for the measurement of aerosol properties are described. Methods considered include: solar aureole photographic technique; densitometric techniques; and video electronic isodensity mapper. Other topics briefly discussed include: multiple scattering experiment; multiple scattering computer program; the generation of the Mie theory results; and the NASA/OAST technology workshop.

Deepak, A.↗
DOE OSTI2026

A novel compact end-loaded piston cylinder cell for high pressure neutron scattering up to 5 GPa

Here, a miniature sized end-loaded piston cylinder cell with radial side windows for neutron scattering experiments is described. The principle of the bicone-shaped cylinders used was first presented by McWhan in 1974. The present cell is of compact portable design yet significantly enlarges the scattering angles. Its small size allows neutron scattering experiments at low temperatures. The bicone-shaped cylinders are made from various ceramics or a highly neutron-transmissive Ni-free Cr–Mo–V steel. Successful neutron scattering experiments up to 5 GPa have been demonstrated on the CORELLI single-crystal diffractometer and the VISION vibrational spectrometer of the Spallation Neutron Source at the Oak Ridge National Laboratory.

Neutrons↗
DOE OSTI2024

Quantitative x-ray scattering of free molecules

Advances in x-ray free electron lasers have made ultrafast scattering a powerful method for investigating molecular reaction kinetics and dynamics. Accurate measurement of the ground-state, static scattering signals of the reacting molecules is pivotal for these pump-probe x-ray scattering experiments as they are the cornerstone for interpreting the observed structural dynamics. Here, this article presents a data calibration procedure, designed for gas-phase x-ray scattering experiments conducted at the Linac Coherent Light Source x-ray Free-Electron Laser at SLAC National Accelerator Laboratory, that makes it possible to derive a quantitative dependence of the scattering signal on the scattering vector. A self-calibration algorithm that optimizes the detector position without reference to a computed pattern is introduced. Angle-of-scattering corrections that account for several small experimental non-idealities are reported. Their implementation leads to near quantitative agreement with theoretical scattering patterns calculated with ab-initio methods as illustrated for two x-ray photon energies and several molecular test systems.

74 ATOMIC AND MOLECULAR PHYSICS↗
NASA NTRS1986

The ionization structure of the circumstellar envelope of Alpha Orionis

The physical processes which affect the ionization of the outer circumstellar envelope of Alpha Ori are analyzed and evaluated. The ultraviolet radiation fields of the chromosphere and the interstellar medium dominate the envelope, and the most common forms of all species are neutral atoms and first ions. Hydrogen recombines just outside the chromosphere, where atoms with smaller ionization potential are essentially fully ionized. The heavier ions gradually recombine with increasing distance from the star, until the interstellar radiation field reverses this trend. The electron fraction in the outer envelope is approximately equal to the abundance of all such heavy atoms, i.e., of the order of 0.0001. The analysis is applied to the case of neutral K, whose density in the envelope has been determined by scattering experiments. The theory predicts that the slope of the K I density distribution should decrease from -1.5 to -3.5 in the outer envelope. The mass loss rate of Alpha Ori implied by the K I scattering experiments is 4 x 10 to the -6th solar mass/yr.

Glassgold, A. E.↗
DOE OSTI2025

Static and dynamic properties of atomic nuclei with high-resolution potentials

Here, we compute ground-state and dynamical properties of 4 He and 16 O nuclei using as input high-resolution, phenomenological nucleon-nucleon and three-nucleon forces that are local in coordinate space. The nuclear Schrodinger equation for both nuclei is accurately solved employing the auxiliary-field diffusion Monte Carlo approach. For the 4 He nucleus, detailed benchmarks are carried out with the hyperspherical harmonics method. In addition to presenting results for the binding energies and radii, we also analyze the momentum distributions of these nuclei and their Euclidean response function corresponding to the isoscalar density transition. The latter quantity is particularly relevant for lepton-nucleus scattering experiments, as it paves the way to quantum Monte Carlo calculations of electroweak response functions of 16 O.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗