Pitch angle distributions of solar energetic particles and the local scattering properties of the interplanetary medium

Journal Article · Mon Dec 01 04:00:00 EST 1986 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/164784· OSTI ID:6483652

Beeck, J; Wibberenz, G

A diffusive approximation of the Fokker-Planck equation is presented which contains adiabatic focusing and pitch angle scattering as elementary processes. The normalized anisotropic part of the distribution function, presented in closed analytical form, is uniquely determined by observable quantities and is independent of time throughout a solar event. It depends only on the local values of the ratio of the mean free path to the focusing length and on the shape of the pitch angle diffusion coefficient. The solution is not limited to weak focusing as long as the solar injection process lasts sufficiently long. Some numerical examples are given, and the application of the model to observations represented by a Legendre expansion up to the fourth order are discussed. Deviations from quasi-linear theory and the influence of helicity on the angular distributions are discussed. The method is also applied to solar particle events aboard the space probes Helios 1 and 2. 40 references.

• Research Organization: Kiel Universitaet, West Germany
• OSTI ID: 6483652
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 311; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ADIABATIC PROCESSES
ANGULAR DISTRIBUTION
DIFFERENTIAL EQUATIONS
DIFFUSION
DISTRIBUTION
DISTRIBUTION FUNCTIONS
EQUATIONS
FOKKER-PLANCK EQUATION
FUNCTIONS
INTERPLANETARY SPACE
PARTIAL DIFFERENTIAL EQUATIONS
RADIATIONS
SCATTERING
SOLAR ACTIVITY
SOLAR FLARES
SOLAR PARTICLES
SOLAR RADIATION
SPACE
STELLAR RADIATION