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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Solar Wind Induced Waves in the Skies of Mars: Ionospheric Compression, Energization, and Escape Resulting from the Impact of Ultralow Frequency Magnetosonic Waves Generated Upstream of the Martian Bow Shock

Using data from the National Aeronautics and Space Administration Mars Atmosphere and Voltatile EvolutioN and the European Space Agency Mars Express spacecraft, we show that transient phenomena in the foreshock and solar wind can directly inject energy into the ionosphere of Mars. We demonstrate that the impact of compressive ultralow frequency waves in the solar wind on the induced magnetospheres drive compressional, linearly polarized, magnetosonic ultralow frequency waves in the ionosphere, and a localized electromagnetic "ringing" at the local proton gyro frequency. The pulsations heat and energize Ionospheric plasmas. A preliminary survey of events shows that no special upstream conditions are required in the interplanetary magnetic field or solar wind. Elevated ion densities and temperatures in the solar wind near to Mars are consistent with the presence of an additional population of Martian ions, leading to ion-ion instabilities, associated wave-particle interactions, and heating of the solar wind. The phenomenon was found to be seasonal, occurring when Mars is near perihelion. Finally, we present simultaneous multipoint observations of the phenomenon, with the Mars Express observing the waves upstream, and Mars Atmosphere and Voltatile EvolutioN observing the response in the ionosphere. When these new observations are combined with decades of previous studies, they collectively provide strong evidence for a previously undemonstrated atmospheric loss process at unmagnetized planets: ionospheric escape driven by the direct impact of transient phenomena from the foreshock and solar wind.

Collinson, Glyn↗
NASA NTRS1990

Ultra high temperature particle bed reactor design

A direct nuclear propulsion engine which could be used for a mission to Mars is designed. The main features of this reactor design are high values for I(sub sp) and very efficient cooling. This particle bed reactor consists of 37 cylindrical fuel elements embedded in a cylinder of beryllium which acts as a moderator and reflector. The fuel consists of a packed bed of spherical fissionable fuel particles. Gaseous H2 passes over the fuel bed, removes the heat, and is exhausted out of the rocket. The design was found to be neutronically critical and to have tolerable heating rates. Therefore, this particle bed reactor design is suitable as a propulsion unit for this mission.

Lazareth, Otto↗
NASA NTRS1992

An analytical approach for the prediction of gamma-to-alpha phase transformation of aluminum oxide (Al2O3) particles in the Space Shuttle ASRM and RSRM exhausts

The analytical approach developed here utilizes the flow-field output from industry standard nozzle and plume codes as input into a particle phase conversion code which predicts the amount of gamma-to-alpha conversion in SRM exhausts. Sixty different cases were considered which varied such parameters as particle size, degree of undercooling, motor type, and altitude. On-centerline calculations were made for both the ASRM and RSRM at an altitude of 100,000 feet with particle sizes varying from 3.5 to 9.1 micron radius and undercooling varying from 0 to 20 percent. Additional calculations were made for the ASRM at 100,000 feet off centerline and at an altitude of 60,000 feet on centerline. The results indicate that significant amounts of metastable alumina will be present in ASRM and RSRM exhausts. Though not significant to motor performance, this may be important in such issues as environmental effects of rocket exhausts, plume radiative heating predictions, and particle size determination by laser scattering.

Oliver, S. M.↗
NASA NTRS1989

Atmospheric entry heating of micrometeorites

A computer simulation of the atmospheric entry deceleration and heating of cosmic dust particles has been developed and the predicted peak temperatures are compared to the earlier closed-form mathematical solutions of Whipple (195) and Fraundorf (1980). A 20-micron diameter particle of density 1 gm/cu cm having a velocity of 10 km/s at infinity and entering the atmosphere at normal incidence reaches a peak temperature of 1159 K. The duration of the heating pulse is about 8 s but the particle remains within 100 K of the peak temperature for only 1.0 s. As the angle of incidence decreases, the peak temperature reached on entry also decreases, and the duration of the temperature pulse increases. Comparison with the Whipple amd Fraundorf models indicates that they accurately assess the entry heating for cosmic dust particles of moderate or higher densities and entry angles near normal incidence. As particle density decreases or the entry angle nears grazing incidence, they overestimate the peak temperature.

Flynn, G. J.↗
NASA NTRS1988

Plasma acceleration, injection, and loss - Observational aspects

A history of the understanding of the sudden accelerations of charged particles noted in plasmas, and the accompanying intrusions of energized plasma into adjacent regions of space, is presented. It is pointed out that studies of the earth's magnetosphere are hampered by the lack of adequate sampling in space and time. Although the feature matching technique of building magnetic and electric field models can help compensate for the sparseness of experimental data, future studies will nonetheless require large numbers of spacecraft placed in carefully coordinated orbits. The notion that the ignition of portions of the auroral shell in association with earth flares results in the heating of ionospheric particles that are then convected inward to form the ring current is considered.

Mcilwain, C. E.↗
NASA NTRS1978

A phenomenological model of solar flares

The energy of solar flares is derived from the magnetic energy of fields convected to the sun's surface and subsequently converted to heat and energetic particles within the chromosphere. The circumstances of this conversion in most current models is magnetic flux annihilation at a neutral sheet. An analysis is conducted of the constraints of flux annihilation. It is shown that the present evidence of solar cosmic rays, X-rays, gamma-rays, and total energy suggests a choice of annihilation not at a neutral point, but by an enhanced dissipation of a field-aligned current. The field configuration is related both to its origin and to the extensive theory and laboratory experiments concerned with this configuration in magnetic fusion. The magnetic field model is applied to the August 4 flare. It is shown how the plasma heating in the annihilation region balanced by thermal conduction leads to a plasma temperature of about 20 million deg K.

Colgate, S. A.↗
NASA NTRS1950

Isentropic phase changes in dissociating gases and the method of sound dispersion for the investigation of homogeneous gas reactions with very high speed : Conclusion

The analytical results of Part I are also applied to sound dispersion by friction and heat conduction, An irreversible change of momentum, energy, and type of particle corresponding to friction, heat conduction, and diffusion effects can appear both in the direction of the sound field and traverse to it. Longitudinal damping, the coupling of longitudinal damping and that due to chemical and physical changes, and coupling of diffusion and compositional changes are treated for a plane sound wave of infinite extent. The same principles are also applied to sound effects in cylindrical tubes. The limitations of the method are discussed in some detail.

SOUND VELOCITY - GASES↗
NASA NTRS2022

Revolutionizing Our Understanding of Particle Energization in Space Plasmas Using on-Board Wave-Particle Correlator Instrumentation

A leap forward in our understanding of particle energization in plasmas throughout the heliosphere is essential to answer longstanding questions in heliophysics, including the heating of the solar corona, acceleration of the solar wind, and energization of particles that lead to observable phenomena, such as the Earth’s aurora. The low densities and high temperatures of typical heliospheric environments lead to weakly collisional plasma conditions. Under these conditions, the energization of particles occurs primarily through collisionless interactions between the electromagnetic fields and the individual plasma particles with energies characteristic of a particular interaction. To understand how the plasma heating and particle acceleration impacts the macroscopic evolution of the heliosphere, impacting phenomena such as extreme space weather, it is critical to understand these collisionless wave-particle interactions on the characteristic ion and electron kinetic timescales. Such understanding requires high-cadence measurements of both the electromagnetic fields and the three-dimensional particle velocity distributions. Although existing instrument technology enables these measurements, a major challenge to maximize the scientific return from these measurements is the limited amount of data that can be transmitted to the ground due to telemetry constraints. A valuable, but underutilized, approach to overcome this limitation is to compute on-board correlations of the maximum-cadence field and particle measurements to improve the sampling time by several orders of magnitude. Here we review the fundamentals of the innovative field-particle correlation technique, present a formulation of the technique that can be implemented as an on-board wave-particle correlator, and estimate results that can be achieved with existing instrumental capabilities for particle velocity distribution measurements.

plasma heating↗
NASA NTRS1970

Optically activated magnetic recording tape

Optically activated data storage medium visually and electromagnetically reproduces a recorded signal. In an electric field, particles in heat-fluidized thermoplastic layer form a visible image of the recorded signal. Refluidizing the thermoplastic layer erases the signals. Very high data packing densities are achieved.

Marks, A. M.↗
NASA NTRS1975

Neutral composition gravity waves in the thermosphere observed by ESRO 4

Neutral composition waves with a wave length of about 5000 km and a wave period of about 2.5 hours were observed by ESRO 4 in the altitude region of 250 km. The amplitudes are of the order of 25 percent for Ar, 15 percent for N2, and roughly 10 percent for He and O at 25 percent geographic latitude. The wave amplitudes are seen to decrease towards lower latitudes suggesting that the composition waves are launched by auroral sources. Simultaneous ground based ionosonde measurements of the F2 layer critical frequency at mid and low latitudes show a wave period consistent with the satellite observations. The theoretical investigation with a multi-component model shows that diffusion plays a major role in explaining these wave phenomena. The phase and amplitude relation between atmospheric constituents are sensitive to the altitude region in which energy is deposited thus suggesting that Joule heating or soft particle precipitation are the predominant energy sources.

Trinks, H.↗
NASA NTRS1974

Apollo scientific experiments data handbook

A brief description of each of the Apollo scientific experiments was described, together with its operational history, the data content and formats, and the availability of the data. The lunar surface experiments described are the passive seismic, active seismic, lunar surface magnetometer, solar wind spectrometer, suprathermal ion detector, heat flow, charged particle, cold cathode gage, lunar geology, laser ranging retroreflector, cosmic ray detector, lunar portable magnetometer, traverse gravimeter, soil mechanics, far UV camera (lunar surface), lunar ejecta and meteorites, surface electrical properties, lunar atmospheric composition, lunar surface gravimeter, lunar seismic profiling, neutron flux, and dust detector. The orbital experiments described are the gamma-ray spectrometer, X-ray fluorescence, alpha-particle spectrometer, S-band transponder, mass spectrometer, far UV spectrometer, bistatic radar, IR scanning radiometer, particle shadows, magnetometer, lunar sounder, and laser altimeter. A brief listing of the mapping products available and information on the sample program were also included.

Eichelman, W. F.↗
NASA NTRS1976

Test data from small solid propellant rocket motor plume measurements (FA-21)

A program is described for obtaining a reliable, parametric set of measurements in the exhaust plumes of solid propellant rocket motors. Plume measurements included pressures, temperatures, forces, heat transfer rates, particle sampling, and high-speed movies. Approximately 210,000 digital data points and 15,000 movie frames were acquired. Measurements were made at points in the plumes via rake-mounted probes, and on the surface of a large plate impinged by the exhaust plume. Parametric variations were made in pressure altitude, propellant aluminum loading, impinged plate incidence angle and distance from nozzle exit to plate or rake. Reliability was incorporated by continual use of repeat runs. The test setup of the various hardware items is described along with an account of test procedures. Test results and data accuracy are discussed. Format of the data presentation is detailed. Complete data are included in the appendix.

Hair, L. M.↗
NASA NTRS1977

Lunar transient phenomena /LTP/ - Manifestations, site distribution, correlations and possible causes

More than 1400 observations of lunar transient phenomena (LTP), encompassing brightenings, darkenings, and gaseous, reddish, and bluish events, are analyzed in an attempt to determine the possible causes of LTP. Hypotheses considered include effects of earth tides on the moon, low-angle illumination, thermal luminescence, UV heating, solar-particle acceleration by the magnetopause of earth's magnetotail, terrestrial magnetotail bow-shock-front turbulence, cathode luminescence due to magnetotail effects, and solar-flare particle bombardment. Analysis are performed in terms of histograms of the number of observations vs. phase of anomalistic period and of number vs. moon's age, percentage of numbers of observed phenomena and percentage of expected numbers as well as their ratios, and albedo behavior over a lunation period of chosen permanent points in ten specific features. The results indicate that different phenomena may have different causes, strong tidal effects are dubious, correlations with sunrise are most frequent, and the distribution of all LTP sites is distinct from that of deep- and shallow-focus moonquake epicenters.

Cameron, W. S.↗
NASA NTRS1978

Magnetospheric substorms

The generation of magnetospheric substorms as a magnetospheric response to a rectangular wave of a component of the interplanetary magnetic field is discussed. The development and decay of auroral substorms (the only visible manifestations of magnetic substorms) are described with reference to auroral particle precipitation, joule heat dissipation, and ring current injection. Various models of substorm phenomena are reviewed, including: (1) the conversion of magnetotail magnetic energy, (2) hot plasma injection from the plasma sheet into the Van Allen belt and ring current formation, (3) field-aligned currents and the auroral electrojet, and (4) the nature of interplanetary magnetic field fluctuations.

Akasofu, S.-I.↗
NASA NTRS1978

Solar wind stream interfaces

Results are presented for a superposed epoch analysis of discontinuous solar wind interfaces. The average time-space profiles of stream interfaces are discussed with reference to fluid properties (flow speed, pressure ridge, density, electron and proton temperatures) and kinetic properties (electron core and halo, flow speed fluctuations, electron heat flux, alpha particles). Other aspects of stream interfaces are described, such as the persistence of individual interfaces, shock associations, the sector boundaries of the interplanetary magnetic field, and sudden impulses in the geomagnetic field. Interface position is considered in terms of the observed temperature jump. A conceptual model of high-speed stream evolution is proposed.

Gosling, J. T.↗
NASA NTRS1984

The remarkable ultraviolet spectrum of the planetary nebula Abell 30

Abell 30 has been identified as a planetary nebula in which the nucleus has experienced a final helium shell flash after ejection of the original, outer envelope. Around the central star of the nebula, four knots of material are observed. In view of the importance of the chemical composition of the ejected material for studies of advanced stages of stellar evolution, clarification of the physical conditions in the knots is vital. Data obtained of Abell 30 with the aid of the International Ultraviolet Explorer (IUE) satellite are discussed along with aspects of extinction, the He II flux, ionic abundances, the C II lambda 4267 line, questions regarding the existence of a carbon-rich core in the knot, the heating of the nebular gas, the central star, and heating by suprathermal particles from the stellar wind. The UV spectrum of the inner nebulosity of Abell 30 indicates that an extraordinary amount of energy is being deposited in the gas.

Harrington, J. P.↗