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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1963

MAGNETIC FORMING

Investigation of the manipulation of solid electrical conductors with high-intensity transient magnetic fields known as magnetic forming

ELECTRIC CONDUCTOR↗
NASA NTRS1969

Magnetic forming of resistive materials

Necessary theoretical foundation is given for the treatment of magnetic stresses applied to cylindrical boundaries and swaging of metallic tubing. Emphasis is placed on the use of high-resistivity materials such as stainless steel and Hastelloy.

Waniek, R. W.↗
NASA NTRS1983

Estimation of lower crust magnetization form satellite derived anomaly field

Various lines of evidence point to the lower crust as the source of the long-wavelength magnetic anomaly field measured by the POGO and Magsat satellites. Using seismically determined lower crust thicknesses and equivalent source inversion of the satellite anomaly data, magnetization for the lower crust for much of the United States has been calculated. The average magnetization for two hundred sixty-six 150 x 150 km areas is 3.5 A/m with a standard deviation of 1.1 A/m. These values are consistent with laboratory measurements of mafic-ultramafic rocks expected in the lower crust, and in agreement with previous estimates of lower crust magnetization based on long-wavelength aeromagnetic data. Average lower crust thickness for the same areas is 18.2 km (sigma = 6.4). Thus, over large regions, it appears that variation in magnetization and variation in magnetic layer thickness contribute almost equally in causing the anomaly field variation at satellite altitude.

Schnetzler, C. C.↗
NASA NTRS1968

Magnetic forming studies

Investigation of the tensile strength dependability on the characteristic time over which a pressure pulse is applied to a metal workpiece shows that the mechanical properties of these materials are functions of the rate at which the material is undergoing strain. These results and techniques are used in magnetomotive metal forming.

Furth, H. P.↗
NASA NTRS1967

Magnetic forming studies

Elastodynamic approach to measuring stress-strain relationship of uniaxially stressed wire, and elastodynamic behavior of electromagnetically stressed material

Source record↗
NASA NTRS1993

A mechanism for the multiple brightenings of dayside poleward-moving auroral forms

Magnetic reconnection plays an important role in the magnetosphere-ionosphere coupling and may lead to the formation of the dayside auroras. Observations of the dayside auroras may provide clues to the reconnection process at the magnetopause. Recently Fasel et al. (1992) observed poleward-moving dayside auroral forms that rebrighten during their lifetimes. Lee et. al. (1993) examined the topology of magnetic flux ropes formed by the patchy multiple X-line reconnection (PMXR), in which a magnetic flux tube reconnects with other flux tubes at multiple sites of limited extent. This paper develops the connection between the evolution of the magnetic flux ropes and the multiple brighentings of poleward-moving dayside auroral forms.

Fasel, G. J.↗
NASA NTRS1974

Magnetopause rotational forms

Magnetic field data from the Goddard Space Flight Center magnetometer experiment on board Ogo 5 are analyzed by the minimum-variance technique for two magnetopause crossings, believed to provide the best evidence presently available of magnetopause rotational discontinuities. Approximate agreement with predictions from MHD and first-order orbit theory is found, but available low-energy electron data suggest the presence of significant non-MHD effects. The paper also illustrates an improved method for data interval selection, a new magnetopause hodogram representation, and the utility of data simulation.

Sonnerup, B. U. O.↗
NASA NTRS1999

Thermal Sensitivity of MD Hematite: Implication for Magnetic Anomalies

Magnetic remanence of crustal rocks can reside in three common rock-forming magnetic minerals: magnetite, pyrrhotite, and hematite. Thermoremanent magnetization (TRM) of magnetite and pyrrhotite is carried mostly by single domain (SD) grains. The TRM of hematite grains, however, is carried mostly by multidomain (NM) grains. This characteristic is illustrated by TRM acquisition curves for hematite of variable grainsizes. The transition between truly NM behavior and tendency towards SD behavior his been established between hematite grainsizes of 0. 1 and 0.05 mm. Coarse grainsize of lower crustal rocks and the large sensitivity of MD hematite grains to acquire TRM indicates that hematite could be a significant contributor to long-wavelength magnetic anomalies.

Kletetschka, Gunther↗
NASA NTRS1991

Spin glass freezing and superconductivity in YBa2(Cu(1-x)Fe(x))3O7 alloys

The dynamics were studied of the iron spins in superconducting YBa2(Cu(0.94)Fe(0.06))3O7 by neutron time of flight measurements. Two samples were studied with slightly different characteristics, as shown by resistivity and neutron diffraction measurements. The same dynamical anomalies are observed by neutrons in both samples. Differences appear qualitative but not quantitative. In the whole temperature range, the q-dependence of the magnetic intensity mainly reflects the magnetic form factor of iron which shows that the iron spins are almost uncorrelated. The elastic and quasielastic intensities strongly vary with temperature. A spin glass like freezing is revealed at low temperature by a sharp decrease of the quasielastic intensity, an increase of the 'elastic' or resolution limited intensity and a minimum in the quasielastic width. The freezing temperature (T sub f - 18 K) corresponds to that already determined by a magnetic splitting in Mossbauer experiments. Above T sub f, the relaxation of the iron spins in the paramagnetic state is modified by the occurrence of superconductivity. An increase was observed of the quasielastic intensity and of the quasielastic width at the superconducting transition.

Mirebeau, I.↗
NASA NTRS1982

The reduction, verification and interpretation of MAGSAT magnetic data over Canada

Correlations between the MAGSAT scalar anomaly map produced at the Earth Physics ranch and other geophysical and geological data reveal relationships between high magnetic field and some metamorphic grade shields, as well as between low magnetic field and shield regions of lower metamorphic grade. An intriguing contrast exists between the broad low anomaly field over the Nasen-Gakkel Ridge (a spreading plate margin) and the high anomaly field over Iceland (part of a spreading margin). Both regions have high heat flow, and presumably thin magnetic crust. This indicates that Iceland is quite anomalous in its magnetic character, and possible similarities with the Alpha Ridge are suggested. Interesting correlations exist between MAGSAT anomalies around the North Atlantic, after reconstructing the fit of continents into a prerifting configuration. These correlations suggest that several orogenies in that region have not completely destroyed an ancient magnetization formed in high grade Precambrian rocks.

Coles, R. L.↗
NASA NTRS1979

The Jovian boundary layer as formed by magnetic-anomaly effects

A model is presented in which a plasma boundary layer of Jupiter is formed from plasma of internal origin. It is proposed that, unlike the Earth's boundary layer, which is thought to consist principally of solar wind plasma, Jupiter's boundary layer consists principally of sulphur and oxygen from the Io plasma torus, plus a small component of hydrogen from Jupiter's ionosphere. Fresh plasma is supplied to the boundary layer once each planetary rotation period by a convection pattern that rotates with Jupiter.

Dessler, A. J.↗