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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Thermodynamics of Light Management in Near-Field Thermophotovoltaics

We evaluate near-field thermophotovoltaic (TPV) energy-conversion systems focusing in particular on their open-circuit voltage (V OC ). Unlike previous analyses based largely on numerical simulations with fluctuational electrodynamics, here, we develop an analytic model that captures the physics of near-field TPV systems and can predict their performance metrics. Using our model, we identify two opportunities of TPV systems operating in the near field. First, we show analytically that enhancement of radiative recombination is a natural consequence of operating in the near field. Second, we note that, owing to photon recycling and minimal radiation leakage in near-field operation, the PV cell used in near-field TPV systems can be much thinner compared to those used in solar PV systems. Since nonradiative recombination is a volumetric effect, use of a thinner cell reduces nonradiative losses per unit area. The combination of these two opportunities leads to increasingly large values of V OC as the TPV vacuum gap decreases. Hence, although operation in the near-field was previously perceived to be beneficial for electrical power-density enhancement, here, we emphasize that thin-film near-field TPVs are also significantly advantageous in terms of V OC and consequently conversion efficiency as well as power density. We provide numerical results for an InAs-based thin-film TPV that exhibits efficiency >50% at an emitter temperature as low as 1100 K.

42 ENGINEERING↗
DOE OSTI2012

Inductance and near fields of a loop antenna in a cold magnetoplasma in the whistler frequency band

The influence of a magnetoplasma on the inductance of a circular loop antenna oriented perpendicular to the ambient static magnetic field and operated in the whistler frequency band is studied. Based on a strict electrodynamic approach, the analytical treatment of the antenna reactance is performed for a uniform rf current distribution along the antenna wire. Calculations are made for plasma parameters and operating frequencies typical for active ionospheric experiments and laboratory rf (helicon) sources of dense magnetized plasmas. It is shown that the plasma influence on the inductance of the loop antenna remains relatively weak, even for antennas with dimensions close to half of the longitudinal whistler wavelength, when the rf field distribution in the antenna near zone is strongly different from that in vacuum. The theoretical predictions are confirmed by measurements performed on the large KROT plasma device. The results obtained are of crucial importance for the preparation of active ionospheric experiments and for the matching of loop antennas used in laboratory rf sources of dense magnetized plasmas.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2019

Liquid argon time projection chamber calibration using cosmogenic muons, and measurement of neutrino induced charged kaon production in argon in the charged current mode (MicroBooNE experiment)

The MicroBooNE experiment at Fermilab uses the novel LArTPC technology to reconstruct neutrino interactions with liquid argon. The experiment consists of a detector having an active mass of 85 tons of liquid argon, where the operational electric field of the TPC is 0.273 kV/cm. While BNB neutrino beam at Fermilab is the main source for neutrinos for the experiment having an average energy of ~0.8 GeV, the NUMI neutrino beam at Fermilab also provides high energy neutrinos to perform different physics analyses. The MicroBooNE experiment has been in operation since october 2015. Its major physics goals include investigating into the anomalous production of electron neutrino like events as observed by MiniBooNE and LSND experiments and detail studies of neutrino-argon cross sections at lower neutrino energies. Moreover, the experiment will also serve as R&D for future LArTPC experiments like the already proposed SBN and DUNE programs. One of the major operational requirements of any LArTPC experiment including MicroBooNE is to achieve a high liquid argon purity keeping the electronegative contaminants like H2O and O2 at low concentration levels. This dissertation first describes how to perform an electron attenuation measurement using cosmogenic muons, which provides a handle over the the amount of electronegative impurities inside our detector medium. Likewise this measurement also serves as the first step towards reconstruction of particle energies as MicroBooNE must compensate for the loss of ionization electrons due to capture by electronegative contaminants. Secondly, the discussion is about how to calibrate any LArTPC detector in removing any spatial and temporal variations of the dQ/dx (charge deposited per unit length) spectrum using cosmogenic muons and then how to calculate correct energies of particle interactions with these calibrated out dQ/dx values. The translation of dQ/dx to particle energies (dE/dx - energy deposited per unit lengt h) makes use of the stopping muons coming from neutrino inte! ractions as the standard candle. The final discussion is about the neutrino induced charged kaon production at charged current mode in the lower neutrino energies of MicroBooNE experiment. This measurement is crucial as there is no such measurement so far on argon at the scale of neutrino energies used for MicroBooNE while already existing measurements on lighter nuclear targets are also sparse. This dissertation presents the first identified neutrino induced kaon candidates in MicroBooNE.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Flat-space quantum gravity in the AdS / CFT correspondence

Motivated by the task of understanding microscopic dynamics of an evolving black hole, we present a scheme describing gauge-fixed continuous time evolution of quantum gravitational processes in asymptotically flat spacetime using the algebra of conformal field theory operators. This allows us to study the microscopic dynamics of the Hawking emission process, although obtaining a full S-matrix may require a modification of the minimal scheme. The role of the operator product expansion is to physically interpret the resulting time evolution by decomposing the Hilbert space of the states for the entire system into those for smaller subsystems. We translate the picture of an evaporating black hole previously proposed by the authors into predictions for nonperturbative properties of the conformal field theories that have weakly coupled dual gravitational descriptions. Finally, we also discuss a possible relationship between the present scheme and a reference frame change in the bulk.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Using Geothermal Play Types as an Analogue for Estimating Potential Resource Size

Blind geothermal systems are becoming increasingly common as more geothermal fields are developed. Geothermal development is known to have high risk in the early stages of a project development because reservoir characteristics are relatively unknown until wells are drilled. Play types (or occurrence models) categorize potential geothermal fields into groups based on geologic characteristics. To aid in lowering exploration risk, these groups' reservoir characteristics can be used as analogues in new site exploration. The play type schemes used in this paper were Moeck and Beardsmore play types (Moeck et al. 2014) and Brophy occurrence models (Brophy et al. 2011). Operating geothermal fields throughout the world were classified based on their associated play type, and then reservoir characteristics data were catalogued. The distributions of these characteristics were plotted in histograms to develop probability density functions for each individual characteristic. The probability density functions can be used as input analogues in Monte Carlo estimations of resource potential for similar play types in early exploration phases. A spreadsheet model was created to estimate resource potential in undeveloped fields. The user can choose to input their own values for each reservoir characteristic or choose to use the probability distribution functions provided from the selected play type. This paper also addresses the United States Geological Survey's 1978 and 2008 assessment of geothermal resources by comparing their estimated values to reported values from post-site development. Information from the collected data was used in the comparison for thirty developed sites in the United States. No significant trends or suggestions for methodologies could be made by the comparison.

15 GEOTHERMAL ENERGY↗
DOE OSTI2012

Search for new physics in B{yields}D*{tau}nu-bar {sub {tau}} decay

B physics offers important tests of the Standard Model at low energies. Recently, BaBar observed significant deviations from the Standard Model expectations in the semileptonic B{yields}D{sup (*)}{tau}{nu}{sub {tau}} decays. Interestingly, the measured leptonic B{yields}{tau}{nu} branching fraction also deviates from CKM unitarity predictions. Motivated by these results we investigate the most general set of lowest dimensional effective operators leading to modifications of b{yields}c(u) (semi)tauonic transitions. Allowing for general flavor violation, we find that among possible operator structures, new contributions from right-right vector and right-left scalar quark currents provide viable explanations of the anomalies. In addition, we identify a number of B{yields}D*{tau}{nu}{sub {tau}} transition observables with the power to discriminate among the various effective operators' contributions. They are the differential decay rate, longitudinal D* polarization fraction, D*-{tau} opening angle asymmetry and the {tau} helicity asymmetry.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Electroweak baryogenesis in non-minimal composite Higgs models

We address electroweak baryogenesis in the context of composite Higgs models, pointing out that modifications to the Higgs and top quark sectors can play an important rôle in generating the baryon asymmetry. Our main observation is that composite Higgs models that include a light, gauge singlet scalar in the spectrum [as in the model based on the symmetry breaking pattern SO(6) → SO(5)], provide all necessary ingredients for viable baryogenesis. In particular, the singlet leads to a strongly first-order electroweak phase transition and introduces new sources of CP violation in dimension-five operators involving the top quark. We discuss the amount of baryon asymmetry produced and the experimental constraints on the model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Global limits and interference patterns in dark matter direct detection

We compare the general effective theory of one-body dark matter nucleon interactions to current direct detection experiments in a global multidimensional statistical analysis. We derive exclusion limits on the 28 isoscalar and isovector coupling constants of the theory, and show that current data place interesting constraints on dark matter-nucleon interaction operators usually neglected in this context. We characterize the interference patterns that can arise in dark matter direct detection from pairs of dark matter-nucleon interaction operators, or from isoscalar and isovector components of the same operator. We find that commonly neglected destructive interference effects weaken standard direct detection exclusion limits by up to one order of magnitude in the coupling constants.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Benchmarking simplified template cross sections in W H production

Simplified template cross sections define a framework for the measurement and dissemination of kinematic information in Higgs measurements. We benchmark the currently proposed setup in an analysis of dimension-6 effective field theory operators for W H production. Calculating the Fisher information allows us to quantify the sensitivity of this framework to new physics and study its dependence on phase space. New machine-learning techniques let us compare the simplified template cross section framework to the full, high-dimensional kinematic information. We show that the way in which we truncate the effective theory has a sizable impact on the definition of the optimal simplified template cross sections.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Cogenerating and pre-annihilating dark matter by a new gauge interaction in a unified model

Grand unified theories based on large groups (with rank ≥6) are a natural context for dark matter models. They contain Standard-Model-singlet fermions that could be dark matter candidates, and can contain new non-abelian interactions whose sphalerons convert baryons, leptons, and dark matter into each other, “cogenerating' a dark matter asymmetry comparable to the baryon asymmetry. In this paper it is shown that the same non-abelian interactions can “pre-annihilate' the symmetric component of heavy dark matter particles χ, which then decay late into light stable dark matter particles ζ that inherit their asymmetry. We derive cosmological constraints on the parameters of such models. The mass of χ must be <3000 TeV and their decays must happen when 2×10{sup −7}<T{sub dec}/m{sub χ}<10{sup −4}. It is shown that such decays can come from d=5 operators with coefficients of order 1/M{sub GUT} or 1/M{sub Pℓ}. We present a simple realization of our model based on the group SU(7).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Trace Theorem and Applications

We characterize three-dimensional vector fields on the basis of the trace of a certain combination of normal derivatives, curl, and divergence. We clarify an unconditional connection between the values of a vector-valued function and the values of gradient, curl, and divergence on the boundary, which makes it possible to consider boundary value problems with boundary conditions that involve the basic first order differential operations of field theory.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Improving Solar PV Degradation Prediction Certainty: PREDICTS2 (Final Technical Report)

The rate and type of in-service PV performance degradation vary for different module designs, vintages, and operating climates. The current IEC 61215 module qualification testing standard can be used to identify design and manufacturing flaws that may lead to early life failures, but it was not intended to accurately predict degradation rates in the first 5 to 10 years of a PV plant’s lifetime, nor long-term performance, under varied operating conditions. Correlations between accelerated aging data and real-world degradation data are needed to better predict wear-out degradation in response to environmental stressors, such as elevated temperature, temperature cycling, moisture, wind load, and solar radiation. The PREDICTS2 project aged 36 pristine-condition ‘spare’ modules from a commercial PV power plant in the U.S. Southwest using the IEC 61215 and Qualification Plus (Qual Plus) testing standards. The study is unique in its ability to compare performance degradation data for fielded modules operating outdoors for 6 years in a commercial plant environmental with degradation data for modules of the same make, model and vintage that have been aged artificially in an indoor laboratory. Changes in individual module current-voltage (I-V) curve data were measured before and after the artificial aging process and compared to I-V curve data for the fielded modules. This project advanced the industry’s understanding of how environmental stressors affect performance degradation and established relationships between degradation mechanisms and changes to module electrical parameters and power loss. Improved certainty in degradation rates is expected to be the greatest source of LCOE reduction resulting from this project. Reducing the spread in the degradation rate probability distribution lowers project risk, which translates to lower project financing costs.

14 SOLAR ENERGY↗
DOE OSTI2012

Atmospheric dispersion modeling: Challenges of the Fukushima Daiichi response

In this research, the U.S. Department of Energy’s (DOE) National Atmospheric Release Advisory Center (NARAC) provided a wide range of predictions and analyses as part of the response to the Fukushima Daiichi Nuclear Power Plant accident including: daily Japanese weather forecasts and atmospheric transport predictions to inform planning for field monitoring operations and to provide U.S. government agencies with ongoing situational awareness of meteorological conditions; estimates of possible dose in Japan based on hypothetical U.S. Nuclear Regulatory Commission scenarios of potential radionuclide releases to support protective action planning for U.S. citizens; predictions of possible plume arrival times and dose levels at U.S. locations; and source estimation and plume model refinement based on atmospheric dispersion modeling and available monitoring data.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Model dynamics for quantum computing

A model master equation suitable for quantum computing dynamics is presented. In an ideal quantum computer (QC), a system of qubits evolves in time unitarily and, by virtue of their entanglement, interfere quantum mechanically to solve otherwise intractable problems. In the real situation, a QC is subject to decoherence and attenuation effects due to interaction with an environment and with possible short-term random disturbances and gate deficiencies. The stability of a QC under such attacks is a key issue for the development of realistic devices. We assume that the influence of the environment can be incorporated by a master equation that includes unitary evolution with gates, supplemented by a Lindblad term. Lindblad operators of various types are explored; namely, steady, pulsed, gate friction, and measurement operators. In the master equation, we use the Lindblad term to describe short time intrusions by random Lindblad pulses. The phenomenological master equation is then extended to include a nonlinear Beretta term that describes the evolution of a closed system with increasing entropy. An external Bath environment is stipulated by a fixed temperature in two different ways. Here we explore the case of a simple one-qubit system in preparation for generalization to multi-qubit, qutrit and hybrid qubit–qutrit systems. This model master equation can be used to test the stability of memory and the efficacy of quantum gates. The properties of such hybrid master equations are explored, with emphasis on the role of thermal equilibrium and entropy constraints. Several significant properties of time-dependent qubit evolution are revealed by this simple study. - Highlights: • General realistic density matrix evolution model shown for one qubit. • Unitary pulses & bias yield quantum gates without harmful phase accumulations. • Gate friction, dissipation included by random Lindblad noise pulses. • Bath & entropy terms yield equilibrium; test algorithms, gates act on Larmor grid. • Measurement modeled by strong, fast Lindblad pulses.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2026

Evaluation of the Room Temperature Field Quality Measurements of HL-LHC MQXFA Magnet Assemblies

As a member of the multi-lab U.S. High Luminosity LHC Accelerator Upgrade Project (HL-LHC AUP), Lawrence Berkeley National Laboratory (LBNL) is assembling high-field Nb3Sn low-beta MQXFA quadrupole magnets for eventual installation at CERN as part of the HL-LHC upgrade. Each magnet undergoes room temperature magnetic measurements at two points during the assembly process: once after completion of the coil pack sub-assembly and once after the magnet is fully assembled and pre-loaded. Beyond its use to verify that each magnet assembly can meet operational requirements, the data from this two-stage measurement process allow for investigation into the impact of the pre-loading operation on field quality. Recent measurements on magnet rebuilds as well as exploratory coil pack reconfigurations also provide an opportunity to see in isolation the effects of changes to a magnet’s coil selection or coil layout. In this work, we present the magnetic measurement results of MQXFA magnets assembled or currently in process, focusing particularly on magnets with data corresponding to multiple builds, and discuss trends and insights which may be beneficial for the remaining MQXFA magnet production or for future Nb3Sn accelerator magnets.

Doyle, Jennifer [LBNL, Berkeley] (ORCID:0009000079↗
DOE OSTI2017

Theoretical Calculation and Simulation Studies of Balancing Forces and Axisymmetric Poloidal Halo Current in EAST

A new technology for developing fusion energy is to use hydrogen isotopes i.e., deuterium (D) and tritium (T) which is a combine effort for building up of International Thermonuclear Reactor (ITER) named as Tokamak, which will come into operation in 2020. Handsome amount of work has already been performed by many scientists contingent with plasma shape, halo current and plasma equilibrium properties by numerical techniques. Halo current calculation is the most important work in fusion reactors. In this paper, halo current and plasma cross-section energy have been calculated. The research covers calculation of plasma energy and determines the force on the vessel by magnetic field transformation method, which is the essential part of calculating halo current. Further, vertical displacement event (VDE) up/down halo current models have been calculated. These models give total magnetic field, asymmetric forces, conducting points and poloidal halo current.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Visitor’s Guide to Oliktok Point Atmospheric Radiation Measurement Climate Research Facility, North Slope of Alaska

The importance of Oliktok Point, Alaska, as a focal point for climate research in the Arctic continues to grow with the addition of a U.S. Department of Energy (DOE) Atmospheric Radiation Monitoring (ARM) Climate Research Facility Mobile Facility (AMF) and the expansion of infrastructure to support airborne measurements. The site hosts a suite of instruments for making multi-year, high-fidelity atmospheric measurements; serves as a base of operations for field campaigns; and contains the only Restricted Airspace and Warning Area in the U.S. Arctic, which enables the use of unmanned aircraft systems. The use of this site by climate researchers involves several considerations, including its remoteness, harsh climate, and location amid the North Slope oilfields. This guide is intended to help visitors to Oliktok Point navigate this unique physical and administrative environment, and thereby facilitate safe and productive operations.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

e + e – → ZH process in the SMEFT beyond leading order

We systematically study potential effects of Beyond the Standard Model physics in the e + e – → ZH process. To this end, we include all relevant dimension-6 Standard Model Effective Field Theory operators and work to next-to-leading order (NLO) accuracy in the electroweak coupling. We consider both polarized and unpolarized electron and positron beams and present results for $\sqrt {s}$ = 240, 365 and 500 GeV, emphasizing contributions where the NLO predictions differ significantly from the leading order results. At NLO, a sensitivity arises to operators that do not contribute at tree level, such as the Higgs tri-linear coupling, CP-violating operators, and dimension-6 operators involving the top quark, among many others. We compare the prospects of future e + e – colliders to explore these new physics effects with existing measurements from the LHC, electron EDMs (for CP violating operators), and Z pole measurements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗