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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

A MW scale charging architecture for supporting extreme fast charging of heavy-duty electric vehicles

Extreme fast charging of electric vehicles technologies is coming. Heavy duty electric vehicles (HD-EVs) are in development and are expected to have multipliers bigger in battery capacity compared to the light duty counterparts. To meet short charging times, MW charging will be necessary. This paper presents a MW scale extreme DC fast charger with a communication and control architecture for HD-EVs. The system is validated in a controller hardware in the loop platform.

Starke, Michael↗
NASA NTRS1995

Instruments Sniff Organic Surface Contaminants

Portable instruments detecting both nonvolatile and volatile organic surface contaminants in real time developed. Instruments easy to use: operate under ordinary ambient atmospheric conditions, without need to use messy liquid solvents or install and remove witness plates, and without need to cut specimens from surfaces to be inspected. Principle of detection involves sweeping pure, activated gas across surface spot inspected, then monitoring light emitted at wavelengths characteristic of excited molecules formed by chemical reactions between activated gas and contaminants. Gas activated by dc discharge, radio-frequency induction, microwave radiation, laser beam, hot filaments, or any other suitable means that excites some of gas molecules.

Adler-Golden, Steven↗
NASA NTRS2000

The Low Temperature Microgravity Physics Experiments Project

The Low Temperature Microgravity Physics Facility (LTMPF) is being developed by NASA to provide long duration low temperature and microgravity environment on the International Space Station (ISS) for performing fundamental physics investigations. Currently, six experiments have been selected for flight definition studies. More will be selected in a two-year cycle, through NASA Research Announcement. This program is managed under the Low Temperature Microgravity Physics Experiments Project Office at the Jet Propulsion Laboratory. The facility is being designed to launch and returned to earth on a variety of vehicles including the HII-A and the space shuttle. On orbit, the facility will be connected to the Exposed Facility on the Japanese Experiment Module, Kibo. Features of the facility include a cryostat capable of maintaining super-fluid helium at a temperature of 1.4 K for 5 months, resistance thermometer bridges, multi-stage thermal isolation system, thermometers capable of pico-Kelvin resolution, DC SQUID magnetometers, passive vibration isolation, and magnetic shields with a shielding factor of 80dB. The electronics and software architecture incorporates two VME buses run using the VxWorks operating system. Technically challenging areas in the design effort include the following: 1) A long cryogen life that survives several launch and test cycles without the need to replace support straps for the helium tank. 2) The minimization of heat generation in the sample stage caused by launch vibration 3) The design of compact and lightweight DC SQUID electronics. 4) The minimization of RF interference for the measurement of heat at pico-Watt level. 5) Light weighting of the magnetic shields. 6) Implementation of a modular and flexible electronics and software architecture. The first launch is scheduled for mid-2003, on an H-IIA Rocket Transfer Vehicle, out of the Tanegashima Space Center of Japan. Two identical facilities will be built. While one facility is onboard the ISS, the other is re-integrated on the ground with new experiments. When the cryogen of the facility in space are exhausted, it will be swapped with the other facility with the new experiment. A total of 20 science missions are envisioned over the next 20 years.

Holmes, Warren↗
DOE OSTI2021

Ultraviolet (UV) light emitting device (LED) driven photocathode

An apparatus includes an electromechanical x-ray generator (MEXRAY) configured to charged capacitors using a small, high-voltage direct current. The apparatus also includes an ultraviolet (UV) light emitting diode (LED) driven photocathode device configured to control/modulate an electron dose rate of the MEXRAY or other vacuum DC, source.

Watson, Scott Avery↗
NASA NTRS2007

First Results from the Washington D.C. Metropolitan Area Lighting Map Demonstration Project

An experimental portable lightning mapping array (LMA) operating in the upper VHF TV band (Channels 7-13; 174-216 MHz) was deployed in the Washington DC Metropolitan area during the summer 2006 to locate and monitor the overall lightning activity. The LMA network provides total lightning data to support lightning research as well as proxy data to benefit the development of applications for planned observing systems such as the GOES-R Geostationary Lightning Mapper. The portable LMA hardware is a compactly-housed, easily deployed version of the LMA stations installed North Alabama, Oklahoma, and New Mexico, which operate in the lower VHF TV band (Channels 2-6,54-88 MHz). Real-time LMA data products are provided to the National Weather Service Weather Forecast Office (WFO) in Sterling, VA to aid in their forecast and warning operations. Forecasters at WFO Sterling have already found the lightning data from the Washington DC demonstration network to be very useful in assessing the development of storm systems. On July 4,2006, data from the LMA aided forecasters as they monitored an area of convection that later developed into a line of severe storms that moved southward through the Washington DC metropolitan area across the Washington Mall. Additional applications of lightning mapping data in the Baltimore-Washington DC urban environment will be discussed.

Goodman, Steven J.↗
DOE OSTI2023

An evaluation of meteorological data prediction over Washington, D.C.: Comparison of DCNet observations and NAM model outputs

This study presents an example of how outputs of operational and readily-available mesoscale numerical models can be adapted to initialize dispersion calculations within the urban surface roughness layer. Three years of urban meteorological observations from central Washington, DC, are compared against forecast outputs of the North American Mesoscale (NAM) model. NAM wind speed predictions underestimate the observations in light winds and overestimate the measurements in high winds. Average wind directions are consistent. However, an adjustment of the predicted direction of the plume by –20° is needed. The uncertainty associated with this adjustment is large in light NAM wind speed with no evident variation by season. The values of the standard deviation of the wind direction, σθ derived from NAM model outputs underestimate the observations by a small amount (about –1.5 to –2.5°). The results presented here indicate that mesoscale numerical model outputs can provide information adequate for dispersion calculations. However, levels of uncertainty associated with implementation of the suggested procedures increase with decreasing wind speed, causing considerable uncertainty in the implementation of adjustments as low wind speed conditions are approached. Results and recommendations reported here should not be extended to other numerical models or other cities without further testing.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1974

Bio-isolated DC operational amplifier

Possibility of shocks from leakage currents can be reduced by use of isolated preamplifiers. Amplifier consists of battery-powered operational amplifier coupled by means of light-emitting diodes to another amplifier which may be grounded and operated from ac power mains or separate battery supply.

Lee, R. D.↗
NASA NTRS1993

AASE-2 observations of trace carbon species distributions in the mid to upper troposphere

We report tropospheric (altitudes greater than 5 km) observations of CO2, CO, CH4, and light hydrocarbons (C2-C4) over the latitude range from 90 deg N to 23 deg S recorded onboard the NASA DC-8 aircraft during the winter 1992 Second Airborne Arctic Stratospheric Expedition (AASE-2). Mixing ratios for these species exhibited significant north-south gradients with maximum values in subpolar and arctic regions and minima over the southern tropics. At latitudes greater than 40 deg N, the mixing ratios of most species increased significantly over the course of the 3-month measurement period. Also at high northern latitudes, the variations of all relatively long-lived reactive carbon species were linearly correlated with fluctuations of CO2 with CO, CH4, C2H6, C2H2, C3H8, and n-C4H10 exhibiting average enhancement ratios in terms of ppbv(X)/ppmb(CO2) of 13.8, 8.4, 0.21, 0.075, 0.085, and 0.037, respectively.

Anderson, B. E.↗
NASA NTRS1993

AASE-2 Observations of Trace Carbon Species Distributions in the Mid to Upper Troposphere

We report tropospheric (altitudes greater than 5 km) observations of CO2, CO, CH4, and light hydrocarbons (C2-C4) over the latitude range from 90 deg N to 23 deg S recorded onboard the NASA DC-8 aircraft during the winter 1992 Second Airborne Arctic Stratospheric Expedition (AASE-II). Mixing ratios for these species exhibited significant north-south gradients with maximum values in subpolar and arctic regions and minima over the southern tropics. At latitudes greater than 40 deg N, the mixing ratios of most species increased significantly over the course of the 3-month measurement period. Also at high northern latitudes, the variations of all relatively long-lived reactive carbon species were linearly correlated with fluctuations of CO2 with CO, CH4, C2H6, C2H2, C3H8, and n-C4H10 exhibiting average enhancement ratios in terms of ppbv(X)/ppmv(CO2) of 13.8, 8.4, 0.21, 0.075, 0.085, and 0.037, respectively.

Anderson, B. E.↗
DOE OSTI2020

Lightwave terahertz quantum manipulation of nonequilibrium superconductor phases and their collective modes

In this work, we present a gauge-invariant density matrix description of nonequilibrium superconductor (SC) states with spatial and temporal correlations driven by intense terahertz (THz) lightwaves. We derive superconductor Bloch-Maxwell equations of motion that extend Anderson pseudospin models to include the Cooper pair center-of-mass motion and electromagnetic propagation effects. We thus describe quantum control of dynamical phases, collective modes, quasiparticle coherence, and high nonlinearities during cycles of carrier wave oscillations, which relates to our recent experiments. Coherent photogeneration of a nonlinear supercurrent with a dc component, achieved via condensate acceleration by an effective lightwave field, dynamically breaks the equilibrium inversion symmetry. Experimental signatures include high harmonic light emission at equilibrium-symmetry-forbidden frequencies, Rabi-Higgs collective modes and quasiparticle coherence, and nonequilibrium moving condensate states tuned by few-cycle THz fields. We use such lightwaves as an oscillating accelerating force that drives strong nonlinearities and anisotropic quasiparticle populations to control and amplify different classes of collective modes, e.g., damped oscillations, persistent oscillations, and overdamped dynamics via Rabi flopping. Recent phase-coherent nonlinear spectroscopy experiments can be modeled by solving the full nonlinear quantum dynamics including self-consistent light-matter coupling.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1981

Controller for computer control of brushless dc motors

A motor speed and torque controller for brushless d.c. motors provides an unusually smooth torque control arrangement. The controller provides a means for controlling a current waveform in each winding of a brushless dc motor by synchronization of an excitation pulse train from a programmable oscillator. Sensing of torque for synchronization is provided by a light beam chopper mounted on the motor rotor shaft. Speed and duty cycle are independently controlled by controlling the frequency and pulse width output of the programmable oscillator. A means is also provided so that current transitions from one motor winding to another is effected without abrupt changes in output torque.

Hieda, L. S.↗
NASA NTRS1988

Synchronous Photodiode-Signal Sampler

Synchronous sampling circuit increases signal-to-noise ratio of measurements of chopped signal of known phase and frequency in presence of low-frequency or dc background noise. Used with linear array of photoelectric sensors for locating edge of metal plate. Multiplexing circuit cycles through 16 light-emitting-diode/photodiode pairs, under computer control. Synchronized with multiplexer so edge detector makes one background-subtracted signal measurement per emitter/detector pair in turn.

Primus, Howard K.↗
NASA NTRS1992

Project Ares 3

The mission of Project Ares is to design and fabricate an Earth prototype, autonomous flying rover capable of flying on the Martian surface. The project was awarded to California State University, Northridge (CSUN) in 1989 where an in-depth paper study was completed. The second year's group, Project Ares 2, designed and fabricated a full-scale flight demonstration aircraft. Project Ares 3, the third and final group, is responsible for propulsion system design and installation, controls and instrumentation, and high altitude testing. The propulsion system consists of a motor and its power supply, geartrain, and propeller. The motor is a four-brush DC motor powered by a 50-V NiCd battery supply. A pulley and belt arrangement is used for the geartrain and includes light weight, low temperature materials. The propeller is constructed from composite materials which ensures high strength and light weight, and is specifically developed to provide thrust at extremely high altitudes. The aircraft is controlled with a ground-based radio control system and an autopilot which will activate in the event that the control signal is lost. A transponder is used to maintain radar contact for ground tracking purposes. The aircraft possesses a small, onboard computer for collecting and storing flight data. To safeguard the possibility of computer failure, all flight data is transmitted to a ground station via a telemetry system. An initial, unpowered, low-level test flight was completed in August of 1991. Testing of systems integration in the second low-level test flight resulted in loss of elevator control which caused considerable damage on landing. Complete failure analysis and repairs are scheduled for September of 1992.

Raymer, Dan↗
NASA NTRS1995

Efficient Quenching of Population Trapping in Excited Yb(+)

We report on a study to determine the efficiency of various buffer gases in quenching the population trapping states of laser-excited ytterbium ions. The ions were confined in an rf-dc hybrid trap, and their (2)S(.5) left and right arrow (2)P(3/2) transition was excited with 329-nm laser light. Buffer gases used include H2, N2, CO2, Ar, and He at several different pressure regimes. We have identified N2 to be highly efficient in quenching the population of the trapping states and thus be the most suitable buffer gas to use with ytterbium for the development of a trapped-ion microwave frequency standard.

Seidel, D. J.↗
NASA NTRS2004

Black Carbon Measurements in SOLVE-2

Droplet Measurement Technologies (DMT), under funding from NASA s Radiation Sciences Program, participated in the SOLVE II field campaign with measurements of light absorbing particles (black carbon and metals). These measurements were made with the Single Particle Soot Photometer (SP-2) on the NASA DC-8. The SP-2 is a new measurement technique that was developed under the SBIR program with funding from the Office of Naval Research. The original instrument suite for the DC-8 did not include the SP-2 and its addition and operation during SOLVE II was intended solely as a means to test its functionality and prepare it for future flight operations. For this reason it required several flights in the early stages of the project to tune its operation and fix some problems that arose. During the flights of January 26, 29, and 30, and February 2, 4 and 6, however, it worked as designed and acquired credible data.

Kok, Gregory L.↗
NASA NTRS1980

Parametric dependence of ion temperature and electron density in the SUMMA hot-ion plasma using laser light scattering and emission spectroscopy

Hot-ion plasma experiments were conducted in the NASA Lewis SUMMA facility. A steady-state modified Penning discharge was formed by applying a radially inward dc electric field of several kilovolts near the magnetic mirror maxima. Results are reported for a hydrogen plasma covering a wide range in midplane magnetic flux densities from 0.5 to 3.37 T. Input power greater than 45 kW was obtained with water-cooled cathodes. Steady-state plasmas with ion kinetic temperatures from 18 to 830 eV were produced and measured spectroscopically. These ion temperatures were correlated with current, voltage, and magnetic flux density as the independent variables. Electron density measurements were made using an unusually sensitive Thomson scattering apparatus. The measured electron densities range from 2.1 x 10 to the 11th to 6.8 x 10 to the 12th per cu cm.

Snyder, A.↗
DOE OSTI2025

Switching of Magnetic Order via Non‐Magnetic Al Addition in FeCoNiMnAl x Films

Magnetic high entropy alloys (HEAs) consisting of 3 d transition metals offer an exciting platform to explore novel magnetic phases as they often house competing exchange interactions in combination with random site disorders. In this work, a sensitive and tunable magnetic order is demonstrated in sputtered single-layer FeCoNiMnAl x films, as a function of non-magnetic Al addition, along with an unexpected exchange bias effect. Thin films of 50 nm FeCoNiMn exhibit a face-centered-cubic ( fcc ) phase, reentrant spin glass (SG) transition near 100 K, and a large exchange bias of over 500 Oe after field-cooling to 5 K. The exchange bias is increased to 930 Oe through a small addition of 5 at.% Al. Further Al addition to 12 at.% results in a body-centered-cubic ( bcc ) phase, coinciding with a large increase in the saturation magnetization, decrease of exchange bias to 50 Oe, and suppression of SG behavior. The change in magnetic order across the Al-induced structural transformation is mediated by the switching of Mn ground state from AF to FM, which is supported by first-principles calculations and experimentally confirmed via X-ray magnetic circular dichroism. These results open up new HEA strategies for explorations of novel magnetic phases.

competing exchange interactions↗
NASA NTRS1981

DC calibration of the strain sensitivity of a single mode optical fiber interferometer

The strain sensitivity of an optical fiber interferometer developed for the detection of pulsed ultrasonic waves in solids was calibrated. Light from the output ends of both fibers was superimposed to form an interference fringe pattern that was interrogated in the far field to give a signal proportional to the differential optical fiber path length. Strain sensitivity is determined by comparing data obtained by clamping and bending the bar at different lengths to simple cantilever beam theory. A minimum theoretical detectable strain of less than 10 to the minus 10th power is indicated.

Claus, R. O.↗