Accession Number:

ADA169412

Title:

A Space Radiation Test Model Study.

Descriptive Note:

Rept. for 20 May 85-20 Feb 86,

Corporate Author:

LOCKHEED MISSILES AND SPACE CO INC PALO ALTO CALIF SPACE SCIENCES LAB

Report Date:

1986-03-14

Pagination or Media Count:

55.0

Abstract:

Dynamic models of the energetic populations in the outer radiation belts are being developed to better understand the extreme variations of particle flux in response to magnetospheric and solar activity. The study utilizes the SCATHA SC3 high energy electron data, covering energies from 47 keV to 5 MeV with fine pitch angle measurements 3 deg field of view over the L-shell range of 5.3 to 8.7. Butter-fly distributions in the dusk sector signify particle losses due to L shell splitting of the particle drift orbits and the subsequent scattering of the particles from the orbits by the magnetopause. To model the temporal variations and diffusion procsses of the particle populations, the data have been organized into phase space distributions, binned according to altitude L shell, energy, pitch angle, and time. These distributions can then be mapped to the equator and plotted for fixed first and second adiabatic invariants of the inherent particle motion. A new and efficient method for calculating the third adiabatic invariant using a line integral of the relevant magnetic potential at the particle mirror points has been developed and is undergoing testing. This method will provide a useful means of displaying the radial diffusion signatures of the outer radiation belts during the more active periods when the L shell parameter is not a good concept due to severe drift-shell splitting. The first phase of fitting the energetic electron phase-space distributions with a combined radial and pitch-angle diffusion formulation is well underway. Bessel functions are being fit to the data in an eigenmode expansion method to determine the diffusion coefficients.

Subject Categories:

  • Astrophysics
  • Atmospheric Physics
  • Plasma Physics and Magnetohydrodynamics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE