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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Effects of zero van der Waals and zero electrostatic forces on droplet sedimentation

The present investigation provides a confirmation of the dependence of droplet sedimentation on particle concentration. It is shown that it is possible to determine the maximum particle concentration which can remain stable on a given liquid from droplet sedimentation experiments. Droplet sedimentation can be reduced but not totally eliminated by the addition of appropriate amounts of dimethyl sulfoxide (DMSO) to reduce the van der Waals forces to zero. It was found that, at 12% DMSO, a maximum particle concentration of 6.3 x 10 to the 8th cells/ml of glutaraldehyde-fixed human erythrocytes suspended in physiological saline can remain stable on a D2O cushion.

Omenyi, S. N.↗
NASA NTRS2017

Lower Hybrid Frequency Range Waves Generated by Ion Polarization Drift Due to Electromagnetic Ion Cyclotron Waves: Analysis of an Event Observed by the Van Allen Probe B

We analyze a wave event that occurred near noon between 07:03 and 07:08 UT on 23 February 2014 detected by the Van Allen Probes B spacecraft, where waves in the lower hybrid frequency range (LHFR) and electromagnetic ion cyclotron (EMIC) waves are observed to be highly correlated, with Pearson correlation coefficient of approximately 0.86. We assume that the correlation is the result of LHFR wave generation by the ions polarization drift in the electric field of the EMIC waves. To check this assumption the drift velocities of electrons and H+, He+, and O+ ions in the measured EMIC wave electric field were modeled. Then the LHFR wave linear instantaneous growth rates for plasma with these changing drift velocities and different plasma compositions were calculated. The time distribution of these growth rates, their frequency distribution, and the frequency dependence of the ratio of the LHFR wave power spectral density (PSD)parallel and perpendicular to the ambient magnetic eld to the total PSD were found. These characteristics of the growth rates were compared with the corresponding characteristics of the observed LHFR activity. Reasonable agreement between these features and the strong correlation between EMIC and LHFR energy densities support the assumption that the LHFR wave generation can be caused by the ions polarization drift in the electric field of an EMIC wave.

Van Allen Probes↗
NASA NTRS1960

Observations of the Van Allen Radiation Regions During August and September 1959

An integrating ionization chamber and a single Geiger counter were flown on United States satellite Explorer VI in an elliptical orbit extending to 48,000 km. In addition to the Van Allen inner zone and the great outer zone, a stable and distinct intermediate zone was detected throughout August and September 1959. The outer-zone intensity showed a large decrease following the sudden commencement of a geomagnetic storm. Later in the storm the outer zone increased to much in excess of its prestorm level. During stable periods the outer zone was fairly constant and less intense than it had been observed to be with Pioneer III or Pioneer IV or the first Soviet cosmic rocket. Cosmic-ray background counting rates were reached on most passes in August and Septmeber near apogee of the satellite. The radiation ?dumped? from the outer zone during the geomagnetic storm fits very well with the intensity and latitude distribution required to account for balloon observations of auroral X rays made during the IGY period. This paper is based on preliminary analysis of Explorer VI data.

Arnoldy, R. L.↗
NASA NTRS1959

Van Allen Discovery Most Important

The first step toward the exploration of space occurred approximately 22 months ago as a part of the International Geophysical Year. In the short interval since October, 1957, the new tools of research, the satellite and the space rocket, have produced two unexpected results of fundamental scientific importance. First, instruments placed in the Explorer satellites by James A. Van Allen have revealed the existence of layers of energetic particles in the outer atmosphere. This discovery constitutes the most significant research achievement of the IGY satellite program. The layers may provide the explanation for the aurora and other geophysical phenomena, and they will also influence the design of vehicles for manned space flight, whose occupants must be shielded against their harmful biological effects. Second, the shape of the earth has been determined very accurately with the aid of data from the first Vanguard. As a result of this investigation, we have found that our planet tends toward the shape of a pear, with its stem at the North Pole. This discovery may produce major changes in our ideas on the interior structure of the earth.

Jastrow, R.↗