Engineering topics
Publications and source records attributed to Mead, G. D..
Procedure for calculating three components of vector field from spherical harmonic using either geocentric or geodetic coordinates as input and output is described. Three subroutines of computer program are explained. Program is written in FORTRAN for IBM 360 computer.
Jupiter's electron and proton radiation belts were analyzed, with particular reference to the effect of its five inner satellites, located within its magnetosphere. The characteristics of trapped electrons and protons with a magnetic moment of 50 MeV/gauss, considered typical at Jupiter, were calculated. The mean absorption time before impact was calculated for particles located at the radial distance of each of the satellites. A characteristic diffusion time near each satellite was calculated, assuming violation of the third invariant due to magnetic fluctuations associated with fluctuations in the solar wind. This diffusion time was found to be long compared with the absorption lifetimes at Europa and Amalthea.
Proton diffusion data are calculated for the Jovian satellites Amalthea, Io, Europa, Ganymede, and Callisto, assuming an equatorial magnetic field at Jupiter's surface of 10 gauss. The cyclotron radius, bounce period, and drift period are calculated for 1 MeV protons. These characteristics and the proton energy at the satellite, mean life near the satellite before impact, and diffusion time are also calculated for 100 MeV protons which conserve their first adiabatic invariant. The longitudinal distance between successive bounces is of the order of a few satellite radii.
A set of computer programs has been developed for the calculation of the geomagnetic field and the tracing of field lines in space. The basic subroutine, geocentric ALLMAG, contains coefficients for seven recently-published field models as built-in data statements. At execution time the user can vary the model and/or the time period by simply changing input parameters. Subroutine GDALMG is adapted for input and output in geodetic coordinates. ALLMAG and GDALMG are equivalent to Cain's FIELD and FIELDG, with the added flexibility of the choice of seven models. LINTRA traces field lines from any point in space to a specified altitude intersect in the same or opposite hemisphere, using any of the models contained in ALLMAG. Input is in either geocentric or geodetic coordinates, and output is returned in both. McIlwain's INVAR package, which calculates B and L, has been adapted to use ALLMAG. All programs are described in detail, and sample calculations are given.
The relationship between solar activity and geomagnetic variations is discussed in the light of spacecraft data obtained during the last decade. The effects of centers of solar activity responsible for producing geomagnetic activity on earth are believed to be transmitted through the solar wind, and there is usually a delay of two or three days before the onset of magnetic activity. Attempts to make a one-to-one correspondence between specific solar events and specific magnetic storms, however, are usually unsuccessful, because of the complex and indirect processes linking the two phenomena. Normally, only statistical tendencies can be shown.
Ground based optical observation of raylike artificial auroras produced by rocket-borne accelerator generated electron beams, using image orthicon TV system
Computer program transforming spherical harmonic coefficients into arbitrarily tilted coordinate systems, tabulating coefficients of International Geomagnetic Reference Field 1965 in dipole coordinate system
Computer program for transforming spherical harmonic coefficients to geomagnetic dipole coordinates
Generation of artificial auroras by injecting electrons into upper atmosphere from Aerobee rocket-borne accelerator
Neutral points on closed magnetosphere boundary from field free plasma incident upon magnetic dipole
Dayside distortion of geomagnetic field by solar wind beyond 3.5 earth radii measured and compared with three magnetosphere models
Explorer XII satellite measurements of geomagnetic field distortion by solar wind
Magnetic field topology near neutral points in closed magnetosphere
Rocket and satellite research bibliography on magnetic and electric fields, and cosmic energetic particles
Shape of magnetosphere and distortion of geomagnetic field
Magnetosphere shape and distortion of magnetic field within magnetosphere
Diffusion of protons in outer radiation belt due to violation of third adiabatic invariant for trapped particles
Adiabatic theory of distorted motion of charged particles in geomagnetic field, showing dependence on equatorial pitch angle