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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Multiplexed Force and Deflection Sensing Shell Membranes for Robotic Manipulators

Force sensing is an essential requirement for dexterous robot manipulation, e.g., for extravehicular robots making vehicle repairs. Although strain gauges have been widely used, a new sensing approach is desirable for applications that require greater robustness, design flexibility including a high degree of multiplexibility, and immunity to electromagnetic noise. This invention is a force and deflection sensor a flexible shell formed with an elastomer having passageways formed by apertures in the shell, with an optical fiber having one or more Bragg gratings positioned in the passageways for the measurement of force and deflection.

Park, Yong-Lae↗
DOE OSTI2017

Effect of H{sup +} implantation on the optical properties of semi-insulating GaAs crystals in the IR spectral region

The optical properties of semi-insulating GaAs crystals subjected to multienergy hydrogen-ion implantation and treatment in a high-frequency electromagnetic field are studied in the infrared spectral region. It is established that such combined treatment provides a means for substantially increasing the transmittance of GaAs crystals to values characteristic of crystals of high optical quality. On the basis of analysis of the infrared transmittance and reflectance data, Raman spectroscopy data, and atomic-force microscopy data on the surface morphology of the crystals, a physical model is proposed to interpret the effects experimentally observed in the crystals. The model takes into account the interaction of radiation defects with the initial structural defects in the crystals as well as the effect of compensation of defect centers by hydrogen during high-frequency treatment.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Gogny-force-derived effective shell-model Hamiltonian

The density-dependent finite-range Gogny force has been used to derive the effective Hamiltonian for the shell-model calculations of nuclei. The density dependence simulates an equivalent three-body force, while the finite range gives a Gaussian distribution of the interaction in the momentum space and hence leads to an automatic smooth decoupling between low-momentum and high-momentum components of the interaction, which is important for finite-space shell-model calculations. Two-body interaction matrix elements, single-particle energies, and the core energy of the shell model can be determined by the unified Gogny force. The analytical form of the Gogny force is advantageous to treat cross-shell cases, while it is difficult to determine the cross-shell matrix elements and single-particle energies using an empirical Hamiltonian by fitting experimental data with a large number of matrix elements. In this paper, we have applied the Gogny-force effective shell-model Hamiltonian to the p- and sd-shell nuclei. The results show good agreements with experimental data and other calculations using empirical Hamiltonians. The experimentally known neutron drip line of oxygen isotopes and the ground states of typical nuclei 10B and 18N can be reproduced, in which the role of three-body force is non-negligible. Here, the Gogny-force-derived effective Hamiltonian has also been applied to the cross-shell calculations of the sd–pf shell.

20 ≤ A ≤ 38↗
DOE OSTI2024

A self-consistent Hamiltonian model of the ponderomotive force and its structure preserving discretization

In the presence of an inhomogeneous oscillatory electric field, charged particles experience a net force, averaged over the oscillatory timescale, known as the ponderomotive force. We derive a one-dimensional Hamiltonian model which self-consistently couples the electromagnetic field to a plasma which experiences the ponderomotive force. We derive a family of structure preserving discretizations of the model of varying order in space and time using conforming and broken finite element exterior calculus spectral element methods. In all variants of our discretization framework, the method is found to conserve the Casimir invariants of the continuous model to machine precision and the energy to the order of the splitting method used.

Physics↗
NASA NTRS2017

Drag and Lift Forces Between a Rotating Conductive Sphere and a Cylindrical Magnet

Modeling the interaction between a non-uniform magnetic field and a rotating conductive object allows study of the drag force which is used in applications such as eddy current braking and linear induction motors as well as the transition to a repulsive force that is the basis for magnetic levitation systems. Here, we study the interaction between a non-uniform field generated by a cylindrical magnet and a rotating conductive sphere. Each eddy current in the sphere generates a magnetic field which in turn generates another eddy current, eventually feeding back on itself. A two step mathematics process is developed to find a closed form solution in terms of only two eddy currents. However, the complete solution requires decomposition of the magnetic field into a summation of spherical harmonics, making it more suitable for a graduate level electromagnetism lecture or lab. Finally, the forces associated with these currents are calculated and then verified experimentally.

Nurge, Mark A.↗
DOE OSTI2015

On the possible relations between solar activities and global seismicity in the solar cycle 20 to 23

Solar activities consist of high energetic particle streams, electromagnetic radiation, magnetic and orbital gravitational forces. The well-know solar activity main indicator is the existence of sunspot which has mean variation in 11 years, named by solar cycle, allow for the above fluctuations. Solar activities are also related to the space weather affecting all planetary atmospheric variability, moreover to the Earth’s climate variability. Large extreme space and geophysical events (high magnitude earthquakes, explosive volcanic eruptions, magnetic storms, etc.) are hazards for humankind, infrastructure, economies, technology and the activities of civilization. With a growing world population, and with modern reliance on delicate technological systems, human society is becoming increasingly vulnerable to natural hazardous events. The big question arises to the relation between solar forcing energy to the Earth’s global seismic activities. Estimates are needed for the long term occurrence-rate probabilities of these extreme natural hazardous events. We studied connectivity from yearly seismic activities that refer to and sunspot number within the solar cycle 20 to 23 of year 1960 to 2013 (53 years). We found clear evidences that in general high magnitude earthquake events and their depth were related to the low solar activity.

58 GEOSCIENCES↗
DOE OSTI2019

A helical-shape scintillating fiber trigger and tracker system for the DarkLight experiment and beyond

The search for new physics beyond the Standard Model has interesting possibilities at low energies. For example, the recent 6.8σ anomaly reported in the invariant mass of e + e - pairs from 8 Be nuclear transitions and the discrepancy between predicted and measured values of muon g-2 give strong motivations for a protophobic fifth-force model. At low energies, the electromagnetic interaction is well understood and produces straightforward final states, making it an excellent probe of such models. However, to achieve the required precision, an experiment must address the substantially higher rate of electromagnetic backgrounds. Here in this paper, we present the results of simulation studies of a trigger system, motivated by the DarkLight experiment, using helical-shape scintillating fibers in a solenoidal magnetic field to veto electron–proton elastic scattering and the associated radiative processes. We also assess the performance of a tracking detector for lepton final states using scintillating fibers in the same setup.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2013

The momentum of an electromagnetic wave inside a dielectric

The problem of assigning a momentum to an electromagnetic wave packet propagating inside an insulator has become known under the name of the Abraham–Minkowski controversy. In the present paper we re-examine this issue making the hypothesis that the forces exerted on an insulator by an electromagnetic field do not distinguish between polarization and free charges. Under this assumption we show that the Abraham expression for the radiation mechanical momentum is highly favored. -- Highlights: •We discuss an approximation to treat electrodynamics of a dielectric material. •We support the Abraham form for the electromagnetic momentum. •We deduce Snell’s law from the conservation of the Abraham momentum. •We show how to deal with the electric field discontinuity at the dielectric boundary.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRSDate not supplied

Evaluation of Magnet Configurations for Magnetohydrodynamic Trajectory Control during Planetary Entry

Magnetohydrodynamics is a phenomenon that can be harnessed during planetary entry to augment aerodynamic drag and may enable higher mass payloads to safely reach the surface. The magnetohydrodynamic force is quantified over a wide range of freestream conditions using computational fluid dynamics results from a previous study. The force is calculated for an array of small electromagnets, a large non-superconducting magnet, a large superconducting magnet, and a uniform field. The superconducting magnet produces a magnetohydrodynamic force within an order of magnitude of aerodynamic drag for velocities higher than 10 km/s, indicating that it may have a reasonable impact on the trajectory for some cases. The array of small magnets and non-superconducting magnet produced a magnetohydrodynamic force that is less than 1% of the aerodynamic drag, so their magnetic fields are not strong enough to affect an entry trajectory. Additionally, the magnet placement plays an important role in magnetohydrodynamic force magnitude, with a magnet located near the shoulder producing approximately eight times more force than a magnet placed on the axis of symmetry. A mass and power budget for each magnet configuration is given assuming current state-of-the-art magnet technology. This study also discusses implementation challenges for each type of magnet on a spacecraft.

Magnetohydrodynamics↗
DOE OSTI2014

Precise Lifetime Measurements in Light Nuclei for Benchmarking Modern Ab-initio Nuclear Structure Models

A new generation of ab-initio calculations, based on realistic two- and three-body forces, is having a profound impact on our view of how nuclei work. To improve the numerical methods, and the parameterization of 3-body forces, new precise data are needed. Electromagnetic transitions are very sensitive to the dynamics which drive mixing between configurations. We have made a series of precise (< 3%) measurements of electromagnetic transitions in the A=10 nuclei {sup 10}C and {sup 10}Be by using the Doppler Shift Attenuation method carefully. Many interesting features can be reproduced including the strong α clustering. New measurements on {sup 8}Be and {sup 12}Be highlight the interplay between the alpha clusters and their valence neutrons.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2014

Charge-exchange QRPA with the Gogny Force for Axially-symmetric Deformed Nuclei

In recent years fully consistent quasiparticle random-phase approximation (QRPA) calculations using finite range Gogny force have been performed to study electromagnetic excitations of several axially-symmetric deformed nuclei up to the {sup 238}U. Here we present the extension of this approach to the charge-exchange nuclear excitations (pnQRPA). In particular we focus on the Isobaric Analog and Gamow-Teller resonances. A comparison of the predicted GT strength distribution with existing experimental data is presented. The role of nuclear deformation is shown. Special attention is paid to β-decay half-lives calculations for which experimental data exist and for specific isotone chains of relevance for the r-process nucleosynthesis.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2013

The non-random walk of chiral magnetic charge carriers in artificial spin ice

The flow of magnetic charge carriers (dubbed magnetic monopoles) through frustrated spin ice lattices, governed simply by Coulombic forces, represents a new direction in electromagnetism. Artificial spin ice nanoarrays realise this effect at room temperature, where the magnetic charge is carried by domain walls. Control of domain wall path is one important element of utilizing this new medium. By imaging the transit of domain walls across different connected 2D honeycomb structures we contribute an important aspect which will enable that control to be realized. Although apparently equivalent paths are presented to a domain wall as it approaches a Y-shaped vertex from a bar parallel to the field, we observe a stark non-random path distribution, which we attribute to the chirality of the magnetic charges. These observations are supported by detailed statistical modelling and micromagnetic simulations. The identification of chiral control to magnetic charge path selectivity invites analogy with spintronics.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Polarization of photons in matter–antimatter annihilation

In this work we demonstrate the possibility of generation of linear polarization of the electromagnetic field (EMF) due to the quantum effects in matter-antimatter annihilation process for anisotropic space of the I type according to Bianchi. We study the dynamics of this process to estimate the degree of polarisation of the EMF in the external gravitational field of the anisotropic Bianchi I model. It has been established that the quantum effects in matter-antimatter annihilation process in the external gravitational field of the anisotropic Bianchi I model provide contribution to the degree of polarisation of the EMF in quadrupole harmonics.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

The separated electric and magnetic field responses of luminescent bacteria exposed to pulsed microwave irradiation

Electromagnetic fields (EMFs) are ubiquitous in the digital world we inhabit, with microwave and millimetre wave sources of non-ionizing radiation employed extensively in electronics and communications, e.g., in mobile phones and Wi-Fi. Indeed, the advent of 5G systems and the “internet of things” is likely to lead to massive densification of wireless networks. Whilst the thermal effects of EMFs on biological systems are well characterised, their putative non-thermal effects remain a controversial subject. Here, we use the bioluminescent marine bacterium, Vibrio fischeri, to monitor the effects of pulsed microwave electromagnetic fields, of nominal frequency 2.5 GHz, on light emission. Separated electric and magnetic field effects were investigated using a resonant microwave cavity, within which the maxima of each field are separated. For pulsed electric field exposure, the bacteria gave reproducible responses and recovery in light emission. At the lowest pulsed duty cycle (1.25%) and after short durations (100 ms) of exposure to the electric field at power levels of 4.5 W rms, we observed an initial stimulation of bioluminescence, whereas successive microwave pulses became inhibitory. Much of this behaviour is due to thermal effects, as the bacterial light output is very sensitive to the local temperature. Conversely, magnetic field exposure gave no measurable short-term responses even at the highest power levels of 32 W rms. Thus, we were able to detect, de-convolute, and evaluate independently the effects of separated electric and magnetic fields on exposure of a luminescent biological system to microwave irradiation.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Relativistic MHD simulations of collision-induced magnetic dissipation in Poynting-flux-dominated jets/outflows

The question of the energy composition of the jets/outflows in high-energy astrophysical systems, e.g. GRBs, AGNs, is taken up first: Matter-flux-dominated (MFD), σ < 1, and/or Poynting-flux-dominated (PFD), σ >1? The standard fireball IS model and dissipative photosphere model are MFD, while the ICMART (Internal-Collision-induced MAgnetic Reconnection and Turbulence) model is PFD. Motivated by ICMART model and other relevant problems, such as “jets in a jet” model of AGNs, the author investigates the models from the EMF energy dissipation efficiency, relativistic outflow generation, and σ evolution points of view, and simulates collisions between high-σ blobs to mimic the situation of the interactions inside the PFD jets/outflows by using a 3D SRMHD code which solves the conservative form of the ideal MHD equations. σ b,f is calculated from the simulation results (threshold = 1). The efficiency obtained from this hybrid method is similar to the efficiency got from the energy evolution of the simulations (35.2%). Efficiency is nearly σ independent, which is also confirmed by the hybrid method. σ b,i - σ b,f provides an interesting linear relationship. Results of several parameter studies of EMF energy dissipation efficiency are shown.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Dark black holes in the mass gap

Abstract In the standard picture of stellar evolution, pair-instability — the energy loss in stellar cores due to electron-positron pair production — is predicted to prevent the collapse of massive stars into black holes with mass in the range between approximately 50 and 130 solar masses — a range known as the “black hole mass gap”. LIGO and Virgo detection of black hole binary mergers containing one or both black holes with masses in thismass gapthus challenges the standard picture, possibly pointing to an unexpected merger history, unanticipated or poorly understood astrophysical mechanisms, or new physics. Here, we entertain the possibility that a “dark sector” exists, consisting of dark electrons, dark protons, and electromagnetic-like interactions, but no nuclear forces. Dark stars would inevitably form given such dark sector constituents, possibly collapsing into black holes with masses within the mass gap. We study in detail the cooling processes necessary for successful stellar collapse in the dark sector and show that for suitable choices of the particle masses, we indeed predict populating the mass gap with dark sector black holes. In particular, we numerically find that the heavier of the two dark sector massive particles cannot be lighter than, approximately, the visible sector proton for the resulting dark sector black holes to have masses within the mass gap. We discuss constraints on this scenario and how to test it with future, larger black hole merger statistics.

Astronomy & Astrophysics↗
DOE OSTI2021

Possible quenching of static neutron pairing near the N=98 deformed shell gap: Rotational structures in 160,161 Gd

A 160 Gd beam was accelerated to an energy of 1000 MeV and, separately, bombarded thick targets of 154 Sm and 164 Dy in order to observe neutron-rich, rare-earth nuclei via deep-inelastic collision processes. Gammasphere was utilized to observe g-ray emissions. Here, many new states and transitions were observed in 160 Gd as a result of so-called "unsafe" Coulomb excitation. The ground-state band in 160 Gd has been extended to I π = 20 + and a rotational band based on the K π = 4 + state, previously associated with a hexadecapole vibration, was observed up to 18 + . The quasiparticle configuration of the K π = 4 + band has been determined, and its unusual alignment behavior may result from a possible quenching of static neutron pairing. In addition, the band based on the [523]5/2 quasineutron orbital in 161 Gd was extended from 11/2 – to 33/2 – , and also displays the same unusual alignment behavior.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

Modification of Structural, Chemical and Process Properties of Rare Metal Minerals under Treatment by High-Voltage Nanosecond Pulses

The authors have studied the mechanism of controlled modification of composition, structure, chemistry, physicochemical and process properties of columbite, tantalite, zircon and feldspar at the meso-, micro- and nanoscales after nonthermal treatment by high-voltage nanosecond electromagnetic pulses. The studies used methods: X-ray photoelectron spectroscopy, scanning electron and atomic force microscopy, potentiometric titration, electromigration chromatography, Kelvin probe force microscopy, microhardness metering and assessment of hydrophobic behavior and flotation activity of the minerals. It is found that changes in the chemical state of atoms on the surface of minerals are mainly connected with the sequential transformation of stages in the process of formation and modification of a functional cover of mineral surface, with variation in a ratio of different type hydroxyl groups on the surface of columbite, zircon and feldspar, which conditions contrast physicochemical properties of rare metal minerals and improves selectivity of their separation by flotation.

77 NANOSCIENCE AND NANOTECHNOLOGY↗