The origin of polarity asymmetries in the history of the geomagnetic field

The behavior of magnetohydrodynamic stationary modes in the presence of an imposed weak magnetic field originating separately from the dynamo is studied. A rare class of stationary states is found that exhibit high sensitivity to the presence of weak imposed fields. The amplitude of the difference between the total fields of opposite polarity is much larger than the amplitude of the imposed nondynamo fields. It is proposed that Earth's magnetic field operates in such a mode, highly sensitive to the presence of an ambient field. An argument is given to explain why the terrestrial dynamo should choose to operate in one of these rare states. Implications are discussed for the general mechanism of dynamo magnetic field equilibrium in planets

Parton distributions in the photon from γ∗γ\gamma^* \gamma and γ∗p\gamma^* p scattering

Leading order parton distributions in the photon are extracted from the existing $F_2^\gamma$ measurements and the low-$x$ proton structure function. The latter is related to the photon structure function by assuming Gribov factorization to hold at low $x$. The resulting parton distributions in the photon are found to be consistent with the Frankfurt-Gurvich sum rule for the photon.Comment: 8 pages, including 4 figure

Development of advanced digital techniques for data acquisition processing and communication Interim scientific report

Design, video data characteristics, error control, and compression algorithms for Mars television mapping missio

Generation of a dynamo magnetic field in a protoplanetary accretion disk

A new computational technique is developed that allows realistic calculations of dynamo magnetic field generation in disk geometries corresponding to protoplanetary and protostellar accretion disks. The approach is of sufficient generality to allow, in the future, a wide class of accretion disk problems to be solved. Here, basic modes of a disk dynamo are calculated. Spatially localized oscillatory states are found to occur in Keplerain disks. A physical interpretation is given that argues that spatially localized fields of the type found in these calculations constitute the basic modes of a Keplerian disk dynamo

Magnetic flares in the protoplanetary nebula and the origin of meteorite chondrules

This study proposes and analyzes a model for the chondrule forming heating events based on magnetohydrodynamic flares in the corona of the protoplanetary nebula which precipitate energy in the form of energetic plasma along magnetic field lines down toward the face of the nebula. It is found that flare energy release rates sufficient to melt the prechondrular matter, leading to the formation of the chondrules, can occur in the tenuous corona of a protostellar disk. Energy release rates sufficient to achieve melting require that the ambient magnetic field strength be in the range that has been inferred separately from independent meteorite remanent magnetization studies

Measurement of electric fields in the ionosphere, volume 2 Final report, Aug. 1966 - Sep. 1967

Electric field meter, using electron beam deflection techniques, for ionospheric measurement

Measurement of electric fields in the ionosphere. Volume 1 - Technical summary report Final report, Aug. 1966 - Sep. 1967

Design and performance of electron beam electric field meter for ionospheric measurements near spacecraf

The production of BeV potential wells

Production of billion electron volt potential wells by cloud of electrons suspended in magnetic fiel

Development of advanced digital techniques for data acquisition processing and communication Interim scientific report

Image correlation and computerized simulation applied to data acquisition and imaging technique

Possible acceleration of charged particles through the reconnection of magnetic field lines in interplanetary space

Prominent intensity spikes in the flux of protons and alphas with less than 0.5 MeV per charge were observed in the region several hours behind an interplanetary shock front. The small spatial scale of these events and the high anisotropy of the particle flux suggest local acceleration. The spectra of the particles, which are cut off at equal energy per charge, suggest acceleration through an electric field. The possibility is examined that these events have their origin in active magnetic neutral sheets in the shocked solar wind