Engineering topics

Smith, E.

Publications and source records attributed to Smith, E..

60 records · Page 4

NASA NTRS1990

Preparation of a second station for the measurement of solar oscillations of low degree 'l'

An observing station to detect low-degree global solar oscillations is already operational at the Jet Propulsion Laboratory. A second station for continuative measurements of such oscillations has recently been installed and successfully tested in Rome. The high transmission and stability of the magneto-optical filter (MOF) coupled with the lock-in amplifier technique allow analog and real-time detection of oscillation modes with a noise level of only a few cm/s. Observing runs and estimates of the signal-to-noise ratio are shown in time and frequency domains. Routine observations will establish whether the MOF sensitivity and stability are suitable for the detection of stellar oscillations.

Cacciani, A.↗

NASA NTRS1988

Integrated Solar Disk Oscillation Measurements Using the Magneto-Optical Filter: Tests with a Two Station Network

The magneto-optical filter (MOF) was used to get high and intermediate l-modes of solar oscillations. For very low l-modes the imaging capability of the MOF is still attractive since it allows a pixel by pixel intensity normalization. However, a crude attempt to get very low l power spectra from Dopplergrams obtained at Mt. Wilson gave noisy results. This means that a careful analysis of all the factors potentially affecting high resolution Dopplergrams should be accomplished. In order to better investigate this problem, a nonimaging channel using the lock-in amplifier technique was considered. Two systems are now operational, one at JPL and the other at University of Rome. Observations in progress are used to discuss the MOF stability, the noise level, and the possible application in asteroseismology.

Cacciani, Alessandro↗

NASA NTRS1988

Acquisition and Reduction Procedures for MOF Doppler-Magnetograms

Defects in the first magneto-optical filter (MOF) magnetograms, particularly the problem of the apparent contamination between velocity and magnetic fields, are discussed. It is found that a correct acquisition and reduction procedure gives cleaner results. A vector magnetograph is suggested. The vector field at coronal levels is calculated, using one MOF longitudinal magnetogram.

Cacciani, Alessandro↗

NASA NTRS1987

Structure and dynamics of the plasma tail of comet P/Halley. I - Knot event on December 31, 1985

On the basis of about 500 photographs of comet Halley taken by many observers, Saito et al. (1986) classified the detected disturbances of the plasma tail as outstanding rays, streamer, helix, kink, arcade, and disconnection event (DE). In this paper, the interaction of the solar wind with the plasma tail of Comet P/Halley is examined by using results of observations by the Sakigake spacecraft of the December 31, 1985 event, which included various disturbances and one DE-like knot. On the basis of twenty photographs taken on December 31 by Japanese astronomers, the dynamic pressure model proposed by Saito et al. (1986) is examined, and the mechnism of the knot event that appeared in the plasma tail of the comet on December 31, is explained.

Saito, T.↗

NASA NTRS1985

Magnetic fields on the sun and the north-south component of transient variations of the interplanetary magnetic field at 1 AU

In order to study the relationship between solar magnetic fields and the transient variations of the north-south component B(Z) of the interplanetary magnetic field (IMF) at 1 AU, flares from unusual north-south oriented active regions, large IMF B(Z) events, and large flares with comprehensive flare index higher than 12 were collected. The associated IMF B(Z) changes or the magnetic field of the initiating flares are investigated. For those cases where an association between a transient B(Z) variation and an initiating flare is plausible, it is found that, for a given flare field, the orientation of the corresponding transient variation of B(Z) may be in agreement with the flare field, opposite to it, or more often, fluctuating in both magnitude and direction. Conversely, an IMF B(Z) event may originate in a flare field in the same magnetic orientation, opposite to it, or in the east-west orientation.

Tang, F.↗

NASA NTRS1967

Water vapor electrolysis.

Mass spectrometric analysis of electrolyte degradation during electrolysis in sulfuric acid silica gel cell for oxygen recovery

ELECTROLYSIS↗