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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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Tunable electromagnetic and broadband microwave absorption of SiO2-coated FeSiAl absorbents
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Characteristic analysis and optimal survey area definition for semi-airborne transient electromagnetics
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Hierarchical Fe3O4@carbon@MnO2 hybrid for electromagnetic wave absorber
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Extension of the Lorenz–Mie–Debye method for electromagnetic scattering to the time-domain
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Double absorbing boundaries for finite-difference time-domain electromagnetics
We describe the implementation of optimal local radiation boundary condition sequences for second order finite difference approximations to Maxwell's equations and the scalar wave equation using the double absorbing boundary formulation. Numerical experiments are presented which demonstrate that the design accuracy of the boundary conditions is achieved and, for comparable effort, exceeds that of a convolution perfectly matched layer with reasonably chosen parameters. An advantage of the proposed approach is that parameters can be chosen using an accurate a priori error bound.
An implicit particle code with exact energy and charge conservation for electromagnetic studies of dense plasmas
A collisional particle code based on implicit energy- and charge-conserving methods is presented. A modified version of the particle-suppressed Jacobian-Free Newton-Krylov method that can enhance the solver efficiency is introduced. Mathematically, it is shown that this new approach can be viewed as a fixed-point iteration method for the particle positions. The model can exactly conserve global energy and local charge and can efficiently use time steps larger than the plasma period. In conclusion, the algorithm's ability to simulate dense plasmas accurately and efficiently is quantified by simulating the dynamic compression of a plasma slab via a magnetic piston in 1D planar geometry.
Irradiation response of commercial, high-Tc superconducting tapes: Electromagnetic transport properties
Effects of low dose irradiation on the electrical transport current properties of commercially available high-temperature superconducting, coated-conductor tapes were investigated, in view of potential applications in the irradiative environment of fusion reactors. Three different tapes, each with unique as-grown flux-pinning structures, were irradiated with Au and Ni ions at energies that provide a range of damage effects, with accumulated damage levels near that expected for conductors in a fusion reactor environment. Measurements using transport current determined the pre- and post-irradiation resistivity, critical current density, and pinning force density, yielding critical temperatures, irreversibility lines, and inferred vortex creep rates. Results show that at the irradiation damage levels tested, any detriment to as-grown pre-irradiation properties is modest; indeed in one case already-superior pinning forces are enhanced, leading to higher critical currents.
Solvothermal synthesis, electromagnetic and electrochemical properties of jellylike cylinder graphene-Mn{sub 3}O{sub 4} composite with highly coupled effect
Jellylike cylinder graphene-Mn{sub 3}O{sub 4} composite with highly coupled effect was successfully synthesized by a simple solvothermal process. Without using toxic reducing agent and expensive equipment, this method is environmental compatible and suitable for low cost mass production. High capacitance Mn{sub 3}O{sub 4} nanoparticles are homogeneously anchored on excellent conductivity graphene framework and a growth mechanism is hypothesized. Excellent electron conductivity and unique structure of Mn{sub 3}O{sub 4}-graphene composite give rise to various applications such as microwave absorber and electrode material. As a microwave absorber, the composite exhibits lowest reflection loss of −14.2 dB in the frequency range of 2–18 GHz. Good microwave absorption performance is due to the structure of the composite where conductive channels form between nano sized Mn{sub 3}O{sub 4} and high conductivity graphene with defects and dangling bonds. As for electrochemical property, Mn{sub 3}O{sub 4}-graphene composite with coupled effect shows excellent performance with highest specific capacitance of 246.7 F g{sup −1} in saturated K{sub 2}SO{sub 4} at a scan rate of 5 mV s{sup −1}. Good electrochemical property is also attributed to the structure with high utilization of Mn{sub 3}O{sub 4}, fast charge carrier transmission, and excellent electronic conductivity. This composite shows a promising application in absorbing materials and electrodes. - Graphical abstract: Graphene-Mn{sub 3}O{sub 4} composite. Display Omitted - Highlights: • Strongly coupled graphene-Mn{sub 3}O{sub 4} composite is synthesized by a solvothermal method. • Excellent microwave absorption property is ascribed to the composite structure. • Good capacitance performance is attributed to the structure and physical property. • The composite shows promising application in absorbing material, and electrode.
High –p(T) hadronic trigger using electromagnetic calorimeter with the STAR detector
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Design and status of the Mu2e electromagnetic calorimeter
Here, the Mu2e experiment at Fermilab aims at measuring the neutrinoless conversion of a negative muon into an electron and reach a single event sensitivity of 2.5×10 –17 after three years of data taking. The monoenergetic electron produced in the final state, is detected by a high precision tracker and a crystal calorimeter, all embedded in a large superconducting solenoid (SD) surrounded by a cosmic ray veto system. The calorimeter is complementary to the tracker, allowing an independent trigger and powerful particle identification, while seeding the track reconstruction and contributing to remove background tracks mimicking the signal. In order to match these requirements, the calorimeter should have an energy resolution of O(5)% and a time resolution better than 500 ps at 100 MeV. The baseline solution is a calorimeter composed of two disks of BaF 2 crystals read by UV extended, solar blind, Avalanche Photodiode (APDs), which are under development from a JPL, Caltech, RMD consortium. In this paper, the calorimeter design, the R&D; studies carried out so far and the status of engineering are described. A backup alternative setup consisting of a pure CsI crystal matrix read by UV extended Hamamatsu MPPC's is also presented.