4,532 research outputs found

    Magnetic latitude effects in the solar wind

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    The Weber-Davis model of the solar wind is generalized to include the effects of latitude. The principal assumptions of high electrical conductivity, rotational symmetry, the polytropic relation between pressure and density, and a flow-alined field in a system rotating with the sun, are retained. An approximate solution to the resulting equations for spherical boundary conditions at the base of the corona indicates a small component of latitudinal flow toward the solar poles at large distances from the sun as result of latitudinal magnetic forces

    Support of the Third Solar Wind conference

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    The program of invited talks at the Third Solar Wind Conference is provided, with a table of contents of the proceedings

    Apollo particles and fields subsatellite magnetometer experiment

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    The results of the Apollo 15 subsatellite magnetometer experiment are reported. The magnetometer is described including the operation, and specifications. Orbit plots presented are altitude versus time, selenographic longitude versus latitude, and the ecliptic projection of the earth-moon system. The lunar magnetic field, solar wind interaction with the moon, the transfer function of the moon, and the plasma sheet interaction with the moon are discussed

    Note on Hydromagnetic Propagation and Geomagnetic Field Stability

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    In the adjoining letter, Dessler [1961] argues that the interface between the solar wind and the geomagnetic field is stable and cannot, therefore, generate hydromagnetic waves. According to our interpretation, his argument may be paraphrased as follows: He observes that, for many sudden commencement geomagnetic storms, surface magnetograms show no marked change in the level of disturbances from the period before the sudden commencement until well into the initial phase of the storm. He applies the attenuation factors calculated by Francis and Karplus [1960] to the measurements of the 1 cps component of the magnetic disturbances obtained at the surface. From this calculation, he concludes that, during the initial phase of these geomagnetic storms, the amplitudes of hydromagnetic disturbances above the ionosphere are less than 1. Assuming that the sudden commencement indicates the presence of a solar wind, he further concludes that hydromagnetie disturbances are not generated in the region between the geomagnetic field and the solar wind and that this interface is, therefore, inherently stable. He subsequently accounts for the hydromagnetie disturbances which are frequently observed at the earth as having been produced by fluctuations in the energy density of the impinging solar wind

    Quintin C Coleman Jr., Tenor

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    Schwanengesang / Franz Schubert; Little David play on your harp; Weepin Mary; Oh, Rock me Julie / H.T. Burleigh; City Called Heaven / Hall Johnso

    No supercritical supercurvature mode conjecture in one-bubble open inflation

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    In the path integral approach to false vacuum decay with the effect of gravity, there is an unsolved problem, called the negative mode problem. We show that the appearance of a supercritical supercurvature mode in the one-bubble open inflation scenario is equivalent to the existence of a negative mode around the Euclidean bounce solution. Supercritical supercurvature modes are those whose mode functions diverge exponentially for large spatial radius on the time constant hypersurface of the open universe. Then we propose a conjecture that there should be ``no supercritical supercurvature mode''. For a class of models that contains a wide variety of tunneling potentials, this conjecture is shown to be correct.Comment: 11 pages, 3 postscript figures, tarred, gzipped. submitted to Phys. Rev. D1

    High-Intensity and High-Brightness Source of Moderated Positrons Using a Brilliant gamma Beam

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    Presently large efforts are conducted towards the development of highly brilliant gamma beams via Compton back scattering of photons from a high-brilliance electron beam, either on the basis of a normal-conducting electron linac or a (superconducting) Energy Recovery Linac (ERL). Particularly ERL's provide an extremely brilliant electron beam, thus enabling to generate highest-quality gamma beams. A 2.5 MeV gamma beam with an envisaged intensity of 10^15 s^-1, as ultimately envisaged for an ERL-based gamma-beam facility, narrow band width (10^-3), and extremely low emittance (10^-4 mm^2 mrad^2) offers the possibility to produce a high-intensity bright polarized positron beam. Pair production in a face-on irradiated W converter foil (200 micron thick, 10 mm long) would lead to the emission of 2 x 10^13 (fast) positrons per second, which is four orders of magnitude higher compared to strong radioactive ^22Na sources conventionally used in the laboratory.Using a stack of converter foils and subsequent positron moderation, a high-intensity low-energy beam of moderated positrons can be produced. Two different source setups are presented: a high-brightness positron beam with a diameter as low as 0.2 mm, and a high-intensity beam of 3 x 10^11 moderated positrons per second. Hence, profiting from an improved moderation efficiency, the envisaged positron intensity would exceed that of present high-intensity positron sources by a factor of 100.Comment: 9 pages, 3 figure
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