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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 1,711 records · Page 95
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Flexible metal–gas batteries: a potential option for next-generation power accessories for wearable electronics

Flexible metal–gas batteries have become increasingly attractive for use in wearable electronics in the recent years due to their large theoretical energy density and superior adaptability to irregular geometric surfaces, such as the human body. With continuous improvements in design strategies and assembly technologies, the fabrication of various advanced flexible metal–gas batteries has been attempted. In spite of these efforts, the synchronous integration of high flexibility, safety, comfort, and high performance into flexible metal–gas batteries with specifically functionalized configurations still remains a formidable challenge. To resolve these dilemmas, the redesign of cathode catalysts, gel polymer electrolyte, and battery configurations/components has been investigated. In this paper, we review the recent technical advances together with the major dilemmas facing currently available flexible metal–gas batteries, highlighting how flexible cathodes and gel polymer electrolytes with various structures and components can affect the electrochemical performance and functionality of flexible metal–gas batteries. Flexible Zn–air, Li–O 2 /air, and Li–CO 2 batteries are mainly exemplified to elucidate their promising potential. Finally, based on our considerations, unresolved technical hurdles and future research perspectives involving flexible metal–gas batteries for wearable electronics are proposed.

25 ENERGY STORAGE↗
DOE OSTI2026

DIII-D High Field Side Lower Hybrid Current Drive Experiment Overview

In preparation for high field side lower hybrid current drive (HFS LHCD) experiments in DIII-D, the HFS LHCD was to be commissioned and physics experiments commence once the system operated up to 300 kW for 0.5 s. The initial physics experiments sought to characterize coupling, wave propagation, and driven current measurements. In HFS LHCD first campaign, the maximum power was limited to <200 kW due to waveguide pressure leaks limiting the number of available modules and power per module. Here we summarize commissioning progress and initial physics observations. The HFS LHCD coupler was optimized for high qmin, DIII-D discharges where efficient off-axis current at r/a~0.6-0.8 is desired. The coupler n|| spectrum is peaked at 2.7 and is predicted to generate ~0.14 MA/MW coupled for 1.6 MW injected. In preparation, the HFS scrape-off layer density profile was characterized and found to have steeper profiles and lower fluctuation levels than the low field side. Furthermore, the HFS SOL density profile can be accurately predicted using global plasma quantities using machine learning. Thus far, one module has injected ~100 kW for 0.5 s with <5% reflected power. Nonthermal electrons have been observed on lower frequency channels of the electron cyclotron emission radiometer correlated with the LH power indicating core wave absorption. To avoid 30R neutral beam heat flux, a split launcher is proposed to avoid the high heat flux region while maintaining power spectrum and directivity.

Wukitch, Stephen J. [Massachusetts Inst. of Techno↗
DOE OSTI2023

Degradation of Poly- and Perfluoroalkyl Substances (PFASs) in Water via High Power, Energy-Efficient Electron Beam Accelerator

The goal of this study was to evaluate the overall effectiveness of e-beam treatment in the degradation of PFASs in water treatment. This included validation of the expected process flows and required electron beam doses, with the first year dedicated to experimentally assessing the optimal electron beam treatment parameters required to decompose the contaminants of concern. In the second year, FNAL’s technical efforts focused on evaluating three different accelerator technologies that could be implemented in the treatment process of PFASs.

43 PARTICLE ACCELERATORS↗
NASA NTRS1968

Electronic load for testing power generating devices

Instrument tests various electric power generating devices by connecting the devices to the input of the load and comparing their outputs with a reference voltage. The load automatically adjusts until voltage output of the power generating device matches the reference.

Friedman, E. B.↗
NASA NTRS2006

Power Actuation and Switching Module Test Results

The X2000 Power System Electronics (PSE) is a Jet Propulsion Laboratory (JPL) task to develop a new generation of power system building blocks for use on future deep-space missions. The effort includes the development of electronic components and modules that can be used as building blocks in the design of generic spacecraft power systems. All X2000 avionics components and modules are designed for use in centralized or distributed spacecraft architectures. The Power Actuation and Switching Module (PASM) has been developed under the X2000 program. This component enables a modular and scalable design approach for power switching applications, which can result in a wide variety of power switching architectures using this simple building block. The PASM is designed to provide most of the necessary power switching functions of spacecraft for various Deep Space missions including future missions to Mars, comets, Jupiter and its moons. It is fabricated using an ASIC process that is tolerant of high radiation. The development included two application specific integrated circuits (ASICs) and support circuitry all packaged using High Density Interconnect (HDI) technology. It can be operated in series or parallel with other PASMs. It can be used as a high-side or low-side switch and it can drive thruster valves, pyrotechnic devices such as NASA standard initiators, bus shunt resistors, and regular spacecraft component loads. Each PASM contains two independent switches with internal current limiting and over-current trip-off functions to protect the power subsystem from load faults. During turnon and turnoff each switch can limit the rate of current change (di/dt) to a value determined by the user. Three-way majority-voted On/Off commandability and full switch status telemetry (both analog and digital) are built into the module. This paper is a follow up to the one presented at he IECEC 2004 conference that will include the lessons learned and test results from the development.

X2000↗
DOE OSTI2024

Thermal Management of Discretized Heaters Using CuW Microchannel Heat Sinks and FC3283

Single-phase cooling using microchannel heat sinks (MCHS) has become a popular approach for overcoming the thermal challenges associated with high-powered microelectronic devices. Thermal management is one of the largest barriers to higher power densities in electronics and frequently limits overall device performance. The implementation of forced convective cooling via single-phase liquid cooling in MCHS reduces the thermal resistance resulting in lower device temperatures at high-power conditions, which can decrease the package size and extend the lifespan of devices. The goal of the work described in this article was to investigate practical cooling solutions for laser diode bars. This study examined the effectiveness of a copper tungsten (CuW) microchannel heat sink paired with a dielectric coolant (FC3283) for dissipating both discrete and uniform heat fluxes up to 600 W/cm2 across a 0.25-cm2 surface area through a numerical and experimental study. CuW was chosen as the MCHS material because it is thermal expansion matched to GaAs, which is a common laser diode substrate. FC3283 serves as a dielectric coolant that is compatible with power electronics cooling. The microchannels utilized in this work were approximately $365$ $μ$ m deep and $100$ $μ$ m wide resulting in a hydraulic diameter of $160$ $μ$ m. The study investigated the cooling performance across a variety of applied power loads and flow rates to determine optimal effectiveness. The resulting thermal resistance ranged from 0.15 cm2 K/W at the highest flow rate to 0.26 cm2 K/W at the lowest flow rate. Further, the resulting thermal performance from this study demonstrates the importance of considering discrete heat sources separately from uniform heat sources and proved that the unique combination of CuW microchannels with FC3283 can be a promising cooling option toward future advancements of laser diode bars and other high-power microelectronics.

42 ENGINEERING↗
NASA NTRS2013

Solar Flare X-Ray Source Motion as a Response to Electron Spectral Hardening

Context. Solar flare hard X-rays (HXRs) are thought to be produced by nonthermal coronal electrons stopping in the chromosphere, or remaining trapped in the corona. The collisional thick target model (CTTM) predicts that more energetic electrons penetrate to greater column depths along the flare loop. This requires that sources produced by harder power-law injection spectra should appear further down the legs or footpoints of a flareloop. Therefore, the frequently observed hardening of the injected power-law electron spectrum during flare onset should be concurrent with a descending hard X-ray source. Aims. To test this implication of the CTTM by comparing its predicted HXR source locations with those derived from observations of a solar flare which exhibits a nonthermally-dominated spectrum before the peak in HXRs, known as an early impulsive event. Methods. HXR images and spectra of an early impulsive C-class flare were obtained using the Ramaty High-Energy Solar Spectroscopic Imager (RHESSI). Images were reconstructed to produce HXR source height evolutions for three energy bands. Spatially-integrated spectral analysis was performed to isolate nonthermal emission, and to determine the power-law index of the electron injection spectrum. The observed height-time evolutions were then fit with CTTM-based simulated heights for each energy, using the electron spectral indices derived from the RHESSI spectra. Results. The flare emission was found to be dominantly nonthermal above approx. 7 keV, with emission of thermal and nonthermal X-rays likely to be simultaneously observable below that energy. The density structure required for a good match between model and observed source heights agreed with previous studies of flare loop densities. Conclusions. The CTTM has been used to produce a descent of model HXR source heights that compares well with observations of this event. Based on this interpretation, downward motion of nonthermal sources should indeed occur in any flare where there is spectral hardening in the electron distribution during a flare. However, this would often be masked by thermal emission associated with flare plasma pre-heating. As yet, flare models that predict transfer of energy from the corona to the chromosphere by means other than a flux of nonthermal electrons do not predict this observed source descent. Therefore, flares such as this will be key in explaining this elusive energy transfer process.

X-rays↗
NASA NTRS1988

Transport of low- and medium-energy electron and ion beams in seawater and its vapors

A general theory of stopping power for electrons and ions in a target medium (gas, liquid, or thin solid foil) containing neutral as well as positive and negative ions is developed. The approach is quite accurate in the low- and medium-energy range (less than 1 MeV), where the Bethe stopping-power cross section is inaccurate. The energy transfer during individual collisions is treated by the binary-encounter approximation. The theory is applied to determine the stopping power of seawater, whose major components are H2O molecules and Na(+) and Cl(-) ions. The stopping-power cross sections for low- and medium-energy protons in water show excellent agreement with existing measurements.

Erwin, Daniel A.↗
NASA NTRS2005

Concept Developed for an Implanted Stimulated Muscle-Powered Piezoelectric Generator

Implanted electronic devices are typically powered by batteries or transcutaneous power transmission. Batteries must be replaced or recharged, and transcutaneous power sources burden the patient or subject with external equipment prone to failure. A completely self-sustaining implanted power source would alleviate these limitations. Skeletal muscle provides an available autologous power source containing native chemical energy that produces power in excess of the requirements for muscle activation by motor nerve stimulation. A concept has been developed to convert stimulated skeletal muscle power into electrical energy (see the preceding illustration). We propose to connect a piezoelectric generator between a muscle tendon and bone. Electrically stimulated muscle contractions would exert force on the piezoelectric generator, charging a storage circuit that would be used to power the stimulator and other devices.

Lewandowski, Beth↗
NASA NTRS1971

Experimental study of spectral index, mode coupling, and energy cascading in a turbulent, hot-ion plasma.

Experiments are described in which the spectrum of electrostatic potential fluctuations was measured with a capacitive probe in a steady state turbulent plasma confined in a magnetic mirror geometry. The plasma electron concentration ranged between 5 x 10 to the seventh power and 5 x 10 to the eighth power, the electron temperature ranged between 8 and 38 eV, the ion temperature between 350 and 960 eV, and the maximum-magnetic field was 1.0 T. When oscillation peaks were absent, the amplitude spectrum of electrostatic potential fluctuations was found to have a power law dependence on the frequency. The value of the spectral index was influenced by the probe position in the field, and at a certain position, by the plasma characteristics. The spectral index was generally below the value of 2.5 predicted by turbulence theories formulated in k space. The effects on the amplitude spectrum of a sinusoidal external modulation of the anode voltage were assessed over the range between 0 and 100 kHz. The spectra exhibited several mode coupling phenomena, including enhanced harmonics of the externally imposed frequency, and sideband modulation of plasma generated oscillation peaks.

Roth, J. R.↗
DOE OSTI2023

2.5D HI Packaging of the Power Converter using TSV interposer.

Abstract: Advantages of the 2.5D HI (Heterogeneous Integration) electronics packaging of the power electronics compared to PCB packaging will be presented. Current 2.5D packaging effort using TSV (Through Silicon Via) will be presented in terms of fabrication, microstructural analysis, reliability, and thermal simulation.

Chung, Hyunim↗
DOE OSTI2020

Effect of chemical disorder on the electronic stopping of solid solution alloys

The electronic stopping power of nickel-based equiatomic solid solutions alloys NiCr, NiFe and NiCo for protons and alpha projectiles is investigated in detail using real-time time-dependent density functional theory over a wide range of velocities. Recently developed numerical electronic structure methods are used to probe fundamental aspects of electron-ion coupling non-perturbatively and in a fully atomistic context, capturing the effect of the atomic scale disorder. The effects of particular electronic band structures and density of states reflect in the low velocity limit behavior. We compare our results for the alloys with those of a pure nickel target to understand how alloying affects the electronic stopping. We discover that NiCo and NiFe have similar stopping behavior as Ni while NiCr has an asymptotic stopping power that is more than a factor of two larger than its counterparts for velocities below 0.1 a.u.. Overall, we show that the low-velocity limit of electronic stopping power can be manipulated by controlling the broadening of the d-band through the chemical disorder. In this regime, the Bragg’s additive rule for the stopping of composite materials also fails for NiCr.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗