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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 NTRS1989

Neutrinos from SN 1987A - Implications for cooling of the nascent neutron star and the mass of the electron antineutrino

Data on neutrinos from SN 1987A are compared here with parameterized models of the neutrino emission using a consistent and straightforward statistical methodology. The empirically measured detector background spectra are included in the analysis, and the data are compared with a much wider variety of neutrino emission models than was explored previously. It is shown that the inferred neutrino emission model parameters are strongly correlated. The analysis confirms that simple models of the neutrino cooling of the nascent neutron star formed by the SN adequately explain the data. The inferred radius and binding energy of the neutron star are in excellent agreement with model calculations based on a wide range of equations of state. The results also raise the upper limit of the electron antineutrino rest mass to roughly 25 eV at the 95 percent confidence level, roughly 1.5-5 times higher than found previously.

Loredo, Thomas J.↗
DOE OSTI2025

Low Cost High-Performance HRE-Free 3-in-1 Electric Drive Unit

The project team completed work to expand upon American Axle & Manufacturing’s (AAM) baseline technology and develop a high-speed, AC induction electric drive unit (EDU) with total direct-oil-cooling and integrated power electronics. The project accelerated advancements in EDU technology by allowing AAM to build upon the progress made in developing the underlying baseline technologies. The following seven improvements to AAM’s baseline technology were implemented in this research and development program: 1) Increased speed (30k RPM) AC induction motor, 2) Silver-sintering of discrete silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFET) to heat sinks, 3) Electrically insulated rotor bars, 4) Optimized lamination steel, 5) EDU-integrated 650VDC inverter package, 6) Over-molded stator with molded liners, and 7) 650VDC power-dense stator design. The successful development of the technology resulted in a meaningful cost reduction for EDU systems in the market. Coupled with falling battery system costs, lower EDU costs will likely accelerate the market acceptance and related production scaling of battery electric vehicles. The objective of this project was to research, develop, and test a Heavy Rare Earth (HRE)-free 3-In-1 electric drive unit (EDU) that has class leading power density and cost. The key technologies to be developed were anticipated to meet or exceed the Department of Energy (DOE) targets of a cost ≤ $\$$7/kilowatt (kW), power density ≥ 12 kW/liter, and operating voltage ≥ 600 VDC.

33 ADVANCED PROPULSION SYSTEMS↗
NASA NTRS1966

Reliability through packaging design.

Relation between packaging design and cooling, vibration, RF interference and reliability of microelectronic systems used in space vehicles

COOLING SYSTEM↗
NASA NTRS1968

Nighttime cooling of the protonosphere.

Protonosphere nighttime cooling, calculating time dependent electron temperature and density profiles along geomagnetic field lines and electron and energy fluxes

Bauer, P.↗
NASA NTRS1980

Controller for solar-energy systems

Report describes operation and testing of computerized control unit for solar-heating and cooling systems. Unit includes electronics and 'plumbing'. Components are modular. Microprocessor with ROM and RAM operates fans, pumps, and valves, and retains selected data for 32 hours.

Hankins, J. D.↗
NASA NTRS1981

X-ray spectra of solar flares obtained with a high-resolution bent crystal spectrometer

Preliminary results obtained for three solar flares with the bent crystal spectrometer on the SMM are presented. Resonance and satellite lines of Ca XIX and XVIII and Fe XXV and XXIV are observed together with the Fe XXVI Lyman-alpha line. Plasma properties are deduced from line ratios and evidence is presented for changes of line widths coincident with the occurrence of a hard X-ray impulsive burst. Fe K-alpha spectra from a disk center and a limb flare agree with the predictions of a fluorescence excitation model. However, a transient Fe K-alpha burst observed in a third flare may be explained by the collisional ionization of cool iron by energetic electrons.

Culhane, J. L.↗
NASA NTRS1984

Heat-Pipe Thermal Switch

New design isolates components from vibrations. Heat-pipe thermal switch controls temperature of heat source. Ball-and-socket guide rods and bellows allow relative motion of source and its heat sink and protect source from vibrations. Designed for cooling vibration-sensitive electronic components.

Ollendorf, S.↗
NASA NTRS1987

Thermal control of the Lidar In-Space Technology Experiment

The Lidar In-Space Technology Experiment (LITE) will employ lidar techniques to study the atmosphere from space. The LITE instrument will be flown in the Space Shuttle Payload Bay with an earth directed orientation. The experiment thermal control incorporates both active and passive techniques. The Laser Transmitter Module (LTM) and the system electronics will be actively cooled through the Shuttle pallet coolant loop. The receiver system and experiment platform will be passsively controlled through the use of insulation and component surface properties. This paper explains the thermal control techniques used and the analysis results, with primary focus on the receiver system.

Carlson, Ann B.↗
NASA NTRS1988

Development of a 75-watt 60-GHz traveling-wave tube for intersatellite communications

This program covers the initial design and development of a 75 watt, 60 GHz traveling-wave tube for intersatellite communications. The objective frequency band was 59 to 64 GHz, with a minimum tube gain of 35 dB. The objective overall efficiency at saturation was 40 percent. The tube, designated the 961H, used a coupled-cavity interaction circuit with periodic permanent magnet beam focusing to minimize the weight. For efficiency enhancement, it incorporated a four-stage depressed collector capable of radiation cooling in space. The electron gun had a low-temperature (type-M) cathode and an isolated anode. Two tubes were built and tested; one feasibility model with a single-stage collector and one experimental model that incorporated the multistage collector.

Rousseau, A. L.↗
NASA NTRS1990

Heat transfer in space systems; Proceedings of the Symposium, AIAA/ASME Thermophysics and Heat Transfer Conference, Seattle, WA, June 18-20, 1990

Theoretical and experimental studies of heat-tranfer in a space environment are discussed in reviews and reports. Topics addressed include a small-scale two-phase thermosiphon to cool high-power electronics, a low-pressure-drop heat exchanger with integral heat pipe, an analysis of the thermal performance of heat-pipe radiators, measurements of temperature and concentration fields in a rectangular heat pipe, and a simplified aerothermal heating method for axisymmetric blunt bodies. Consideration is given to entropy production in a shock wave, bubble-slug transition in a two-phase liquid-gas flow under microgravity, plasma arc welding under normal and zero gravity, the Microgravity Thaw Experiment, the flow of a thin film on stationary and rotating disks, an advanced ceramic fabric body-mounted radiator for Space Station Freedom phase 0 design, and lunar radiators with specular reflectors.

Chan, S. H.↗
NASA NTRS1991

Collisional processes in cometary plasmas

The interaction of the solar wind with comets is initiated at large distances from the nucleus by the ionization of cometary neutrals. The resulting contamination of the solar wind with cometary ions mass-loads the solar wind flow, causing it to slow down. The plasma-comet interaction is largely collisionless at large cometocentric distances. However, collisional processes become important in the inner coma (within the cometopause). Collisional processes include charge-transfer between solar wind protons and neutrals, ion-neutral friction, electron and ion thermal cooling, and ion-neutral chemistry. For example, the magnetometer on the Giotto spacecraft observed a diamagnetic cavity near closest approach. This cavity is a consequence of the balance between an inward-directed magnetic pressure gradient force and an outward ion-netural frictional force. Thermalization of the cometary ion distribution function by Coulomb collisions is another important process in the inner coma of an active comet.

Cravens, T. E.↗
NASA NTRS1993

Evaluation of high temperature superconductive thermal bridges for space-borne cryogenic infrared detectors

The focus of this research is on the reduction of the refrigeration requirements for infrared sensors operating in space through the use of high temperature superconductive (HTS) materials as electronic leads between the cooled sensors and the relatively warmer data acquisition components. Specifically, this initial study was directed towards the design of an experiment to quantify the thermal performance of these materials in the space environment. First, an intensive review of relevant literature was undertaken, and then, design requirements were formulated. From this background information, a preliminary experimental design was developed. Additional studies will involve a thermal analysis of the experiment and further modifications of the experimental design.

Scott, Elaine P.↗
NASA NTRS1993

Micromachined electron tunneling infrared sensors

The development of an improved Golay cell is reported. This new sensor is constructed entirely from micromachined silicon components. A silicon oxynitride (SiO(x)N(y)) membrane is deflected by the thermal expansion of a small volume of trapped gas. To detect the motion of the membrane, an electron tunneling transducer is used. This sensor detects electrons which tunnel through the classically forbidden barrier between a tip and a surface; the electron current is exponentially dependent on the separation between the tip and the surface. The sensitivity of tunneling transducers constructed was typically better than 10(exp -3) A/square root of Hz. Through use of the electron tunneling transducer, the scaling laws which have prevented the miniaturization of the Golay cell are avoided. This detector potentially offers low cost fabrication, compatibility with silicon readout electronics, and operation without cooling. Most importantly, this detector may offer better sensitivity than any other uncooled infrared sensor, with the exception of the original Golay cell.

Kenny, T. W.↗
NASA NTRS2012

Astrobiological Journeys to and from the South Polar Sea of Enceladus - Bidirectional Interactions with the Saturn Magnetosphere

The spectacularly cryovolcanic moon Enceladus is a major source of plasma for the Saturn magnetosphere via ionization of the ejected molecular species and ice grains. Field-aligned plasma flows from the Enceladus environment visibly impact the moon's magnetic footpoint in Saturn's polar auroral region, while water group and other ions from the moon emissions diffuse radially throughout the magnetosphere and may be the dominant source of oxygen for Titan's oxygen-poor upper atmosphere. But the moon-magnetosphere interaction is bidirectional in the sense that the moon surface is globally exposed to constant irradiation by the returning magnetospheric ions and by energetic electrons from the field-aligned and radially diffusing populations. The returning ion source operates both on global scales of the magnetosphere and locally for highly reactive species produced in the ejecta plume. All of these sources likely combine to produce a highly oxidized global surface layer. Since plasma electrons and ions are cooled by interaction with neutral gas and E-ring ice grains from Enceladus, the moon emissions have a governing effect on the seed populations of energetic particles that irradiate the surface. The proposed subsurface polar sea and transient crustal overturn in the south polar region could bring the polar surface oxidants into contact with hydrocarbons and ammonia to make oxidation product gases contributing to the cryovolcanic jets, a process first proposed by Cooper et al. (Plan. Sp. Sci., 2009). As has been previously suggested for Europa, the 'oxidants could contribute to enhanced astrobiological potential of Enceladus, perhaps even higher than for Europa where organic hydrocarbons have not yet been directly detected. Unlike Europa, Enceladus shows no sign of an oxygen-dominated exosphere that could otherwise be indicative of extreme surface and interior oxidation inhibiting the detectable survival and evolution of complex organics.

Cooper, John F.↗
NASA NTRS2012

VERITAS Observations of Day-scale Flaring of M 87 in 2010 April

VERITAS has been monitoring the very-high-energy (VHE; > 100 GeV) gamma-ray activity of the radio galaxy M 87 since 2007. During 2008, flaring activity on a timescale of a few days was observed with a peak flux of (0.70 +/- 0.16) x 10(exp -11)/sq cm/s at energies above 350 GeV. In 2010 April, VERITAS detected a flare from M 87 with peak flux of (2.71 +/- 0.68) x 10(exp -11)/sq cm/s for E > 350 GeV. The source was observed for six consecutive nights during the flare, resulting in a total of21 hr of good-quality data. The most rapid flux variation occurred on the trailing edge of the flare with an exponential flux decay time of 0,90 +0.22/-0.15 days, The shortest detected exponential rise time is three times as long, at 2.87 +1.65/-0.99 days. The quality of the data sample is such that spectral analysis can he performed for three periods: rising flux, peak flux, and falling flux. The spectra obtained are consistent with power-law forms. The spectral index at the peak of the flare is equal to 2.19 +/- 0.07, There is some indication that the spectrum is softer in the falling phase of the flare than the peak phase, with a confidence level corresponding to 3.6 standard deviations. We discuss the implications of these results for the acceleration and cooling rates of VHE electrons in M 87 and the constraints they provide on the physical size of the emitting region.

Perkins, J. S>↗
NASA NTRS2013

Cooling History of Almahata Sitta Ureilite as Inferred from Transmission Electron Microscopy of Iron Metal

Almahata Sitta (AS) is a polymict breccia mainly composed of various ureilite lithologies with lesser chondritic lithologies [1]. In the ureilite lithologies, Fe metal is a common accessory phase present either as large grain boundary grains or small particles formed by reduction of olivine and pyroxene. In our earlier studies on grain boundary metals in one of AS fragments (#44) we found unique features never seen in other ureilites [2,3]. In order to further characterize these metal grains, we performed a detailed TEM study on a FIB section prepared from one of AS #44 grain boundary metals and here discuss its thermal history.

Mikouchi, T.↗
NASA NTRS1987

Solar EUV induced variations in the thermosphere

The effects of solar activity on the thermosphere are reviewed. The neutral total density, temperature, and electron density increase with solar activity, and their variations are fairly well correlated with variations in solar 10.7-cm flux. The electron temperature, by contrast, has a complex behavior with solar activity, depending on altitude and season, as increased heat input is balanced by increased cooling provided by the enhanced electron density. Also, individual neutral species do not all increase in step but are influenced by dissociation and dynamical processes. The increased ion drag at higher solar activities inhibits the neutral wind from increasing in the same proportion as the neutral temperatures and densities.

Hedin, A. E.↗
NASA NTRS2012

Radioisotope Stirling Engine Powered Airship for Low Altitude Operation on Venus

The feasibility of a Stirling engine powered airship for the near surface exploration of Venus was evaluated. The heat source for the Stirling engine was limited to 10 general purpose heat source (GPHS) blocks. The baseline airship utilized hydrogen as the lifting gas and the electronics and payload were enclosed in a cooled insulated pressure vessel to maintain the internal temperature at 320 K and 1 Bar pressure. The propulsion system consisted of an electric motor driving a propeller. An analysis was set up to size the airship that could operate near the Venus surface based on the available thermal power. The atmospheric conditions on Venus were modeled and used in the analysis. The analysis was an iterative process between sizing the airship to carry a specified payload and the power required to operate the electronics, payload and cooling system as well as provide power to the propulsion system to overcome the drag on the airship. A baseline configuration was determined that could meet the power requirements and operate near the Venus surface. From this baseline design additional trades were made to see how other factors affected the design such as the internal temperature of the payload chamber and the flight altitude. In addition other lifting methods were evaluated such as an evacuated chamber, heated atmospheric gas and augmented heated lifting gas. However none of these methods proved viable.

Colozza, Anthony J.↗