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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 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Ewald Summation Approach to Potential Models of Aqueous Electrolytes Involving Gaussian Charges and Induced Dipoles: Formal and Simulation Results

We present a detailed derivation of the complete set of expressions required for the implementation of an Ewald summation approach to handle the long-range electrostatic interactions of polar and ionic model systems involving Gaussian charges and induced dipole moments with a particular application to the isobaricisothermal molecular dynamics simulation of our Gaussian Charge Polarizable (GCP) water model and its extension to aqueous electrolytes solutions. The set comprises the individual components of the potential energy, electrostatic potential, electrostatic field and gradient, the electrostatic force and the corresponding virial. Moreover, we show how the derived expressions converge to known point-based electrostatic counterparts when the parameters, defining the Gaussian charge and induced-dipole distributions, are extrapolated to their limiting point values. Finally, we illustrate the Ewald implementation against the current reaction field approach by isothermal-isobaric molecular dynamics of ambient GCP water for which we compared the outcomes of the thermodynamic, microstructural, and polarization behavior.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Expert elicitation survey predicts 37% to 49% declines in wind energy costs by 2050

Wind energy has experienced accelerated cost reduction over the past five years—far greater than predicted in a 2015 expert elicitation. Here we report results from a new survey on wind costs, compare those with previous results and discuss the accuracy of the earlier predictions. In this work, we show that experts in 2020 expect future onshore and offshore wind costs to decline 37–49% by 2050, resulting in costs 50% lower than predicted in 2015. This is due to cost reductions witnessed over the past five years and expected continued advancements. If realized, these costs might allow wind to play a larger role in energy supply than previously anticipated. Considering both surveys, we also conclude that there is considerable uncertainty about future costs. Our results illustrate the importance of considering cost uncertainty, highlight the value and limits of using experts to reveal those uncertainties, and yield possible lessons for energy modellers and expert elicitation.

17 WIND ENERGY↗
DOE OSTI2018

Understanding the Stability of Salt-Inclusion Phases for Nuclear Waste-forms through Volume-based Thermodynamics

Abstract Formation enthalpies and Gibbs energies of actinide and rare-earth containing SIMs with silicate and germanate frameworks are reported. Volume-based thermodynamics (VBT) techniques complemented by density functional theory (DFT) were adapted and applied to these complex structures. VBT and DFT results were in closest agreement for the smaller framework silicate structure, whereas DFT in general predicts less negative enthalpies across all SIMs, regardless of framework type. Both methods predict the rare-earth silicates to be the most stable of the comparable structures calculated, with VBT results being in good agreement with the limited experimental values available from drop solution calorimetry.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2019

Feasibility of measuring EDM in spin transparent colliders

A new polarization control mode called a Spin Transparency (ST) mode is currently being actively developed for new rings. The ST mode is an intrinsic feature of figure-8 rings such as the JLEIC at Jefferson Lab. A racetrack collider can be converted to the ST mode by inserting two identical Siberian snakes into its opposite straights as at NICA, JINR. The ST mode allows one to develop a completely new approach to the measurement of the EDMs of both protons and deuterons. The idea of the method is to use the significant enhancement of the EDM signal by the interaction of the EDM with arc magnets, which has an interference effect. A unique feature of this technique is the conceptual capability of measuring the EDM signal in the whole energy range of a ring without introducing additional electric fields using only its magnetic fields. We describe an experimental setup and provide estimates of the limiting EDM values that can be measured at the JLEIC and NICA colliders.

Kondratenko, Anatoliy↗
DOE OSTI2011

Positivity constraints on LECs of {chi}PT lagrangian at O(p{sup 6}) level

Positivity constraints on the LECs of O(p{sup 6}){chi}PT lagrangian are discussed. We demonstrate that the constraints are automatically satisfied inside the Mandelstam triangle for {pi}{pi} scatterings, when N{sub C} is large. Numerical tests are made in the N{sub C} = 3 case, and it is found that these constraints are also well respected.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Laboratory studies of the dynamic of resonance cones formation in magnetized plasmas

The paper is devoted to experimental studies of formation of resonance cones in magnetized plasmas by pulsed RF source in the lower-hybrid (whistler) and the upper-hybrid frequency ranges. It is shown that in both frequency ranges, resonance cones exhibit similar dynamics after switching-on the RF source: at first, wide maxima of radiation are formed in non-resonance directions, which then become narrower, with their direction approaching the resonance one. While the resonance cones are being formed, one observes a fine structure in the form of secondary radiation maxima. It is shown that the characteristic formation time of stationary resonance cones is determined by the minimal value of the group velocity of the quasi-electrostatic waves excited by the antenna. In the low-temperature plasma, this value is limited in the lower-hybrid frequency range by the spatial spectrum of the emitting antenna and in the upper-hybrid range, by the effects of spatial plasma dispersion.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

Dark matter at colliders

We show that colliders can impose strong constraints on dark matter. We take an effective field theory approach where dark matter couples to quarks and gluons through high dimensional operators. We discuss limits on interactions of dark matter and hadronic matter from the ATLAS experiment at the Large Hadron Collider (LHC). For spin-independent scattering, the LHC limits are stronger than those from direct detection experiments for light WIMPs. For spin-dependent scattering, the LHC sets better limits over much of parameter space.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Expectations for neutron-antineutron oscillation time from TeV scale baryogenesis

A TeV scale extension of the standard model that incorporates the seesaw mechanism for neutrino masses along with quark-lepton unification is presented. It is shown that this model leads to the {Delta}B= 2 baryon number violating process of neutron-antineutron (n-bar n) oscillation. The model has all the ingredients to generate the observed baryon asymmetry of the universe using the B-violating decay of a scalar field involved in the seesaw mechanism. The B-violating decay arises from the exchange of color sextet scalars which have TeV scale masses. Baryogenesis occurs below the sphaleron decoupling temperature and has been termed post-sphaleron baryogenesis. Here we show that the constraints of TeV scale baryogenesis, when combined with the neutrino oscillation data and restrictions from flavor changing neutral currents mediated by the colored scalars imply an upper limit on the n-bar n oscillation time of 5 Multiplication-Sign 10{sup 10} sec. regardless of the quark-lepton unification scale. If this scale is relatively low, in the (200 - 250) TeV range, {tau}{sub n-bar} {sub n} is predicted to be less than 10{sup 10} sec., which is accessible to the next generation of proposed experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Radiative inverse seesaw neutrino mass and dark matter

Seesaw mechanism provides a natural explanation of light neutrino masses through suppression of heavy seesaw scale. In inverse seesaw models the seesaw scale can be much lower than that in the usual seesaw models. If terms inducing seesaw masses are further induced by loop corrections, the seesaw scale can be lowered to be in the range probed by experiments at the LHC without fine tuning. This talk, presented by X-G He, discuss models constructed in a recent preprint by us (arxiv:201207.6308) in which neutrino masses are generated at two loop level through inverse seesaw mechanism. These models also naturally have dark matter candidates. Although the recent data from Xenon100 put stringent constraint on the models, they can be consistent with data on neutrino masses, mixing, dark matter relic density and direct detection.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Parametrization of light clusters within relativistic mean field models

Light clusters are included in the equation of state of nuclearmatter within the relativistic mean field theory. The effect of the cluster-meson coupling constants on the dissolution density is discussed. Theoretical and experimental constraints are used to fix the cluster-meson couplings at T Almost-Equal-To 5 MeV.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2013

Direct deposition of aluminum oxide gate dielectric on graphene channel using nitrogen plasma treatment

Deposition of high-quality dielectric on a graphene channel is an essential technology to overcome structural constraints for the development of nano-electronic devices. In this study, we investigated a method for directly depositing aluminum oxide (Al{sub 2}O{sub 3}) on a graphene channel through nitrogen plasma treatment. The deposited Al{sub 2}O{sub 3} thin film on graphene demonstrated excellent dielectric properties with negligible charge trapping and de-trapping in the gate insulator. A top-gate-structural graphene transistor was fabricated using Al{sub 2}O{sub 3} as the gate dielectric with nitrogen plasma treatment on graphene channel region, and exhibited p-type transistor characteristics.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Tokamak halo currents

A halo current flows for part of its path through the plasma edge and for part through the chamber walls and can be as large as tenths of the plasma current. The primary interest in halo currents is the large force that they can exert on machine components. Two discordant constraints are central to the theory: (1) Halo currents must produce the magnetic field distribution required to maintain plasma force balance—a distribution that depends on the two angular coordinates of a torus. (2) Halo currents must flow along the magnetic field lines in the plasma, which implies a dependence on a linear combination of the two angular coordinates—only one angular coordinate is free. The physics basis of these two constraints is explained as is their application to the calculation of the properties of halo currents, such as their broad toroidal spectrum. Existing codes could be used to (1) provide detailed comparisons with experiments to validate that the critical elements of physics are adequately included, (2) allow more complete predictions for future machines such as ITER, and (3) design shunts and resistive elements to ensure halo currents follow paths that are the least damaging to the machine. The physics of halo currents implies that it may be possible to feedback stabilize resistive wall modes beyond the ideal-wall limit.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

Constraint analysis for variational discrete systems

A canonical formalism and constraint analysis for discrete systems subject to a variational action principle are devised. The formalism is equivalent to the covariant formulation, encompasses global and local discrete time evolution moves and naturally incorporates both constant and evolving phase spaces, the latter of which is necessary for a time varying discretization. The different roles of constraints in the discrete and the conditions under which they are first or second class and/or symmetry generators are clarified. The (non-) preservation of constraints and the symplectic structure is discussed; on evolving phase spaces the number of constraints at a fixed time step depends on the initial and final time step of evolution. Moreover, the definition of observables and a reduced phase space is provided; again, on evolving phase spaces the notion of an observable as a propagating degree of freedom requires specification of an initial and final step and crucially depends on this choice, in contrast to the continuum. However, upon restriction to translation invariant systems, one regains the usual time step independence of canonical concepts. This analysis applies, e.g., to discrete mechanics, lattice field theory, quantum gravity models, and numerical analysis.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Comparative study of beam losses and heat loads reduction methods in MITICA beam source

In negative ion electrostatic accelerators a considerable fraction of extracted ions is lost by collision processes causing efficiency loss and heat deposition over the components. Stripping is proportional to the local density of gas, which is steadily injected in the plasma source; its pumping from the extraction and acceleration stages is a key functionality for the prototype of the ITER Neutral Beam Injector, and it can be simulated with the 3D code AVOCADO. Different geometric solutions were tested aiming at the reduction of the gas density. The parameter space considered is limited by constraints given by optics, aiming, voltage holding, beam uniformity, and mechanical feasibility. The guidelines of the optimization process are presented together with the proposed solutions and the results of numerical simulations.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

Phase space gradient of dissipated work and information: A role of relative Fisher information

We show that an information theoretic distance measured by the relative Fisher information between canonical equilibrium phase densities corresponding to forward and backward processes is intimately related to the gradient of the dissipated work in phase space. We present a universal constraint on it via the logarithmic Sobolev inequality. Furthermore, we point out that a possible expression of the lower bound indicates a deep connection in terms of the relative entropy and the Fisher information of the canonical distributions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

Nuclear astrophysics and electron beams

Electron beams provide important probes and constraints for nuclear astrophysics. This is especially exciting at energies within the regime of chiral effective field theory (EFT), which provides a systematic expansion for nuclear forces and electroweak operators based on quantum chromodynamics. This talk discusses some recent highlights and future directions based on chiral EFT, including nuclear structure and reactions for astrophysics, the neutron skin and constraints for the properties of neutron-rich matter in neutron stars and core-collapse supernovae, and the dark matter response of nuclei.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2013

Constrained γZ correction to parity-violating electron scattering

We update the calculation of γZ interference corrections to the weak charge of the proton. We show how constraints from parton distributions, together with new data on parity-violating electron scattering in the resonance region, significantly reduce the uncertainties on the corrections compared to previous estimates.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Searching for an invisible dark photon with DarkLight

The DarkLight experiment at Jefferson Lab is designed to search for a new U(1) vector boson A' in the mass range 10-100 MeV through its decay A′→e{sup +}e{sup −}. We will show that DarkLight is also sensitive to an A' decaying to invisible final states, but because of QED backgrounds, such a search is only feasible with photon detection. Surprisingly, pileup can be mitigated with a cut on the sign of the missing invariant mass-squared. We give the DarkLight reach for the invisible search assuming a nominal two-month running time, and compare to constraints from anomalous magnetic moments and rare kaon decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗