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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Photochemical reactions of various model protocell systems

Models for the emergence of cellular life on the primitive Earth, and for physical environments of that era have been studied that embody these assumptions: (1) pregenetic cellular forms were phase-bounded systems primarily photosynthetic in nature, and (2) the early Earth environment was anoxic (lacking appreciable amounts of free hydrogen). It was found that organic structures can also be formed under anoxic conditions (N2, CO3=, H2O) by protracted longwavelength UV radiation. Apparently these structures form initially as organic layers upon CaCO3 crystalloids. The question remains as to whether the UV photosynthetic ability of such phase bounded structures is a curiosity, or a general property of phase bounded systems which is of direct interest to the emergence of cellular life. The question of the requirement and sailient features of a phase boundary for UV photosynthetic abilities was addressed by searching for similar general physical properties which might be manifest in a variety of other simple protocell-like structures. Since it has been shown that laboratory protocell models can effect the UV photosynthesis of low molecular weight compounds, this reaction is being used as an assay to survey other types of structures for similar UV photosynthetic reactions. Various kinds of structures surveyed are: (1) proteinoids; (2) liposomes; (3) reconstituted cell membrane spheroids; (4) coacervates; and (5) model protocells formed under anoxic conditions.

Folsome, C. E.↗
DOE OSTI2018

A Subthreshold High-Pressure Discharge Excited by a Microwave Beam: Physical Basics and Applications

A new form of discharge excited by a microwave beam in a high-pressure (up to atmospheric and higher) gas in free space and in a closed chamber is discussed. For the first time, the discharge was implemented by means of a gyrotron with a pulse power of 200 ≤ P ≤ 600 kW, a pulse duration of 0.5 ≤ τ ≤ 20 ms, and a wavelength of λ = 0.4 cm. Under deeply subthreshold conditions in atmospheric-pressure air, a plasma column with a length of L = 50 cm was generated by a microwave beam formed with the help of a quasi-optical transmission line. With the use of the MIG-3 gyrotron complex with the above parameters, generation of a plasma column with a length of several meters is possible in principle. The parameters and structure of the formation of the plasma investigated make it possible to class it as a self-non-self-sustained (SNSS) discharge, discovered and described for the first time at the Prokhorov General Physics Institute, Russian Academy of Sciences. One of the important applications of this type of discharge is plasmachemical cleaning of the urban air environment of hazardous contaminants.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2019

“Evaluation of boundary layer cloud processes in an advanced parameterization for global models” (Final Report)

Low clouds over the ocean are a critical component of our planet’s energy budget because they emit almost as much energy as the surface while being much more reflective than the ocean, resulting in a strong net cooling effect. Despite their importance, low marine clouds remain a persistent source of uncertainty in future climate projections. This project explored how the dynamics, thermodynamics and spatial organization of low clouds is represented in a particular physical simplification, or parameterization, of small-scale air motions and cloud processes commonly employed in global atmospheric models used for short-term weather and longer-term earth system prediction. The overall goal was to develop long-term observational products to constrain numerical model representations of turbulence and cloud processes using observations from the US Department of Energy’s (DOE) Atmospheric Radiation Measurement (ARM) program’s Eastern North Atlantic (ENA) site. These constraints were then used to demonstrate the type of information that can be gained from confronting simulations with the observations and we assessed the performance of a parameterization in simulating periods of low clouds at ENA. Finally, we used detailed computational fluid dynamics simulations of turbulence and cloud properties to evaluate general physical assumptions embedded in simplified representations of clouds and turbulence for global models of the atmosphere.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

Toward the analytic bootstrap of energy correlators

In this paper, we present a framework for the analytic bootstrap of three-point energy correlators, a crucial observable in $\mathcal{N}$ = 4 super Yang-Mills theory and quantum chromodynamics (QCD). Our approach combines spherical contour techniques, general physical constraints such as pole cancellations, and power correction data in the singular limits to determine its analytic expression. In contrast to previous bootstrap studies restricted to scattering amplitudes for supersymmetric theories, our framework makes use of the properties of Feynman integrals, marking a significant step toward bootstrapping realistic QCD observables. Using this method, we derive analytic expressions for leading-order three-point energy correlators in the multi-collinear limit with equal and unequal energy weights, where the latter are crucial ingredients for projected N -point energy correlators. We also apply the recently developed technique of analytic regression with lattice reduction as a way to bypass needing explicit expressions for the singular limits. Bridging theoretical advances in scattering amplitudes with the renewed interest in weighted cross-sections, our work opens the door to precision tests of QCD dynamics through analytic event-shape predictions.

jet substructure↗
DOE OSTI2018

On the Pressure of a Neutron Gas Interacting with the Non-Uniform Magnetic Field of a Neutron Star

On the basis of simple arguments, practically not going beyond the scope of an undergraduate course in general physics, we estimate the additional pressure (at zero temperature) of degenerate neutron matter due to its interaction with the non-uniform magnetic field of a neutron star. This work has methodological and possibly scientific value as an intuitive application of the content of such a course to a solution of topical problems of astrophysics.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2016

Response to “The Mössbauer rotor experiment and the general theory of relativity” by C. Corda

We show that a new attempt by Corda (2016), just like his previous attempt (Corda, 2015) that we had answered before (A.L. Kholmetskii et al., 2015), to reinterpret Mössbauer experiments in a rotating system as a “new, strong and independent proof of the correctness of Einstein’s vision of gravity” is erroneous. In addition, we demonstrate that Corda’s criticism of Yarman–Arik–Kholmetskii gravitation theory (in short YARK), is based on the application of ill-posed logic; thus rendering his claims against YARK as unfounded.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

Quasi-particle and collective magnetism: Rotation, pairing and blocking in high-K isomers

For the first time, a wide range of collective magnetic g-factors gR, obtained from a novel analysis of experimental data for multi-quasi-particle configurations in high-K isomers, is shown to exhibit a striking systematic variation with the relative number of proton and neutron quasi-particles, Np Nn. Using the principle of additivity, the quasi-particle contribution to magnetism in high-K isomers of Lu Re, Z=71 75, has been estimated. Based on these estimates, band-structure branching ratio data are used to explore the behavior of the collective contribution as the number and proton/neutron nature (Np, Nn), of the quasi-particle excitations, change. Basic ideas of pairing, its quenching by quasi-particle excitation and the consequent changes to moment of inertia and collective magnetism are discussed. Existing model calculations do not reproduce the observed gR variation adequately. The paired superfluid system of nucleons in these nuclei, and their excitations, present properties of general physics interest. The new-found systematic behavior of gR in multi-quasi-particle excitations of this unique system, showing variation from close to zero for multi-neutron states to above 0.5 for multi-proton states, opens a fresh window on these effects and raises the important question of just which nucleons contribute to the collective properties of these nuclei.

Stone, N. J.↗
DOE OSTI2024

Detecting single gravitons with quantum sensing

The quantization of gravity is widely believed to result in gravitons – particles of discrete energy that form gravitational waves. But their detection has so far been considered impossible. Here we show that signatures of single graviton exchange can be observed in laboratory experiments. We show that stimulated and spontaneous single-graviton processes can become relevant for massive quantum acoustic resonators and that stimulated absorption can be resolved through continuous sensing of quantum jumps. We analyze the feasibility of observing the exchange of single energy quanta between matter and gravitational waves. Our results show that single graviton signatures are within reach of experiments. In analogy to the discovery of the photo-electric effect for photons, such signatures can provide the first experimental clue of the quantization of gravity.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

GENFIRE: A generalized Fourier iterative reconstruction algorithm for high-resolution 3D imaging

Tomography has made a radical impact on diverse fields ranging from the study of 3D atomic arrangements in matter to the study of human health in medicine. Despite its very diverse applications, the core of tomography remains the same, that is, a mathematical method must be implemented to reconstruct the 3D structure of an object from a number of 2D projections. Here, we present the mathematical implementation of a tomographic algorithm, termed GENeralized Fourier Iterative REconstruction (GENFIRE), for high-resolution 3D reconstruction from a limited number of 2D projections. GENFIRE first assembles a 3D Fourier grid with oversampling and then iterates between real and reciprocal space to search for a global solution that is concurrently consistent with the measured data and general physical constraints. The algorithm requires minimal human intervention and also incorporates angular refinement to reduce the tilt angle error. We demonstrate that GENFIRE can produce superior results relative to several other popular tomographic reconstruction techniques through numerical simulations and by experimentally reconstructing the 3D structure of a porous material and a frozen-hydrated marine cyanobacterium. As a result, equipped with a graphical user interface, GENFIRE is freely available from our website and is expected to find broad applications across different disciplines.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Shortcuts to adiabaticity in a time-dependent box

A method is proposed to drive an ultrafast non-adiabatic dynamics of an ultracold gas trapped in a time-dependent box potential. The resulting state is free from spurious excitations associated with the breakdown of adiabaticity, and preserves the quantum correlations of the initial state up to a scaling factor. The process relies on the existence of an adiabatic invariant and the inversion of the dynamical self-similar scaling law dictated by it. Its physical implementation generally requires the use of an auxiliary expulsive potential. The method is extended to a broad family of interacting many-body systems. As illustrative examples we consider the ultrafast expansion of a Tonks-Girardeau gas and of Bose-Einstein condensates in different dimensions, where the method exhibits an excellent robustness against different regimes of interactions and the features of an experimentally realizable box potential.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

Magnetic field advection in two interpenetrating plasma streams

Laser-generated colliding plasma streams can serve as a test-bed for the study of various astrophysical phenomena and the general physics of self-organization. For streams of a sufficiently high kinetic energy, collisions between the ions of one stream with the ions of the other stream are negligible, and the streams can penetrate through each other. On the other hand, the intra-stream collisions for high-Mach-number flows can still be very frequent, so that each stream can be described hydrodynamically. This paper presents an analytical study of the effects that these interpenetrating streams have on large-scale magnetic fields either introduced by external coils or generated in the plasma near the laser targets. Specifically, a problem of the frozen-in constraint is assessed and paradoxical features of the field advection in this system are revealed. A possibility of using this system for studies of magnetic reconnection is mentioned.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2014

PS-1/S1 picosecond streak camera application for multichannel laser system diagnostics

A PS-1/S1 picosecond image-tube streak camera (ITSC) with slit scan (streak camera), developed and manufactured at the General Physics Institute RAS, has been used to measure the spatiotemporal characteristics of ultrashort laser pulses generated by a petawatt-power laser installation 'FEMTO' at the Institute of Laser Physics Research in Sarov. It is found that such a camera is suitable for measuring the spatial and temporal parameters of single laser pulses with an accuracy of about one picosecond. It is shown that the intensity time profile of a train of picosecond pulses may be precisely defined for the pulses separated in time by a few picoseconds. The camera allows the contrast of radiation to be determined with a high (no less than 10{sup 3}) accuracy; spatial distribution of the laser pulses can be measured with an accuracy of tens of microns, and the temporal separation of single laser pulses can be identified with an accuracy of 1 – 1.5 ps. (extreme light fields and their applications)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

PHOTOPHORESIS IN A DILUTE, OPTICALLY THICK MEDIUM AND DUST MOTION IN PROTOPLANETARY DISKS

We derive expressions for the photophoretic force on opaque spherical particles in a dilute gas in the optically thick regime where the radiation field is in local thermal equilibrium. Under those conditions, the radiation field has a simple form, leading to well defined analytical approximations for the photophoretic force that also consider both the internal thermal conduction within the particle, and the effects of heat conduction and radiation to the surrounding gas. We derive these results for homogeneous spherical particles; and for the double layered spheres appropriate for modeling solid grains with porous aggregate mantles. Then, as a specific astrophysical application of these general physical results, we explore the parameter space relevant to the photophoresis driven drift of dust in protoplanetary disks. We show that highly porous silicate grains have sufficiently low thermal conductivities that photophoretic effects, such as significant relative velocities between particles with differing porosity or levitation above the midplane, are expected to occur.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Primordial trispectra and CMB spectral distortions

We study the TTμ bispectrum, generated by correlations between Cosmic Microwave Background temperature (T) anisotropies and chemical potential (μ) distortions, and we analyze its dependence on primordial local trispectrum parameters g{sub NL} and τ{sub NL}. We cross-check our results by comparing the full bispectrum calculation with the expectations from a general physical argument, based on predicting the shape of μ-T correlations from the couplings between short and long perturbation modes induced by primordial non-Gaussianity. We show that both g{sub NL} and τ{sub NL}-parts of the primordial trispectrum source a non-vanishing TTμ signal, contrary to the μμ auto-correlation function, which is sensitive only to the τ{sub NL}-component. A simple Fisher matrix-based forecast shows that a futuristic, cosmic-variance dominated experiment could in principle detect g{sub NL} ∼ 0.4 and τ{sub NL} ∼ 40 using TTμ.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Learning linear optical circuits with coherent states

We analyze the energy and training data requirements for supervised learning of an M-mode linear optical circuit by minimizing an empirical risk defined solely from the action of the circuit on coherent states. When the linear optical circuit acts non-trivially only on k < M unknown modes (i.e. a linear optical k-junta), we provide an energy-efficient, adaptive algorithm that identifies the junta set and learns the circuit. We compare two schemes for allocating a total energy, E, to the learning algorithm. In the first scheme, each of the T random training coherent states has energy E/T. In the second scheme, a single random MT-mode coherent state with energy E is partitioned into T training coherent states. The latter scheme exhibits a polynomial advantage in training data size sufficient for convergence of the empirical risk to the full risk due to concentration of measure on the $(2MT-1)$-sphere. Specifically, generalization bounds for both schemes are proven, which indicate that for ε-approximation of the full risk by the empirical risk with high probability, $O(E^{2/3}M^{2/3}/\epsilon^{2/3})$ training states are sufficient for the first scheme and $O(E^{1/3}M^{1/3}/\epsilon^{2/3})$ training states are sufficient for the second scheme.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

NuGrid stellar data set – III. Updated low-mass AGB models and s-process nucleosynthesis with metallicities Z= 0.01, Z = 0.02, and Z = 0.03

ABSTRACT The production of the neutron-capture isotopes beyond iron that we observe today in the Solar system is the result of the combined contribution of the r-process, the s-process, and possibly the i-process. Low-mass asymptotic giant branch (AGB) (1.5 < M/M⊙ < 3) and massive (M > 10 M⊙) stars have been identified as the main site of the s-process. In this work we consider the evolution and nucleosynthesis of low-mass AGB stars. We provide an update of the NuGrid Set models, adopting the same general physics assumptions but using an updated convective-boundary-mixing model accounting for the contribution from internal gravity waves. The combined data set includes the initial masses MZAMS/M⊙ = 2, 3 for Z = 0.03, 0.02, 0.01. These new models are computed with the mesa stellar code and the evolution is followed up to the end of the AGB phase. The nucleosynthesis was calculated for all isotopes in post-processing with the NuGrid mppnp code. The convective-boundary-mixing model leads to the formation of a 13C-pocket three times wider compared to the one obtained in the previous set of models, bringing the simulation results now in closer agreement with observations. Using these new models, we discuss the potential impact of other processes inducing mixing, like rotation, adopting parametric models compatible with theory and observations. Complete yield data tables, derived data products, and online analytic data access are provided.

79 ASTRONOMY AND ASTROPHYSICS↗