Mean free path of low-energy protons upstream of selected interplanetary shocks

Journal Article · Sat Jul 01 04:00:00 EDT 1989 · Journal of Geophysical Research; (USA)

DOI:https://doi.org/10.1029/JA094iA07p08769· OSTI ID:5834632

Beeck, J; Sanderson, T R ^[1]

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1. European Space Agency, Noordwijk (Netherlands)

There are two fundamentally different approaches in calculating the mean free path of energetic charged particles. The first approach is concerned with the particle data. Here measured time intensity profiles are fitted to theoretical models and a best fit value for the mean free path is obtained. For undisturbed propagation of solar particles this theoretical model usually is a numerical solution of a Fokker-Planck equation. In the case of quasi-parallel interplanetary shocks the mean free path can be determined from the exponential increase of the particles intensity in the upstream region of the shock. The second approach starts with the magnetic field properties. One often-applied model assumes that the scattering of the particles is due to Alfven waves that propagate along the guiding field. Here the particles are scattered resonantly by the components of the field fluctuations perpendicular to the guiding field. A second model assumes that a different type of magnetiohydrodynamic wave, the magnetosonic wave, in addition to Alfven waves plays an important role in particle scattering. The scattering by magnetosonic waves is a nonresonant interaction. The authors discuss the time intensity profiles of low-energy protons (35-1,600 keV) associated with interplanetary shocks observed by ISEE 3 during the period August 1978 to December 1981. For five shock-associated particle intensity increases, they calculate the amount of scattering upstream of the shock by fitting the intensity increase as an exponential in time. The anisotropy in the solar wind frame is analyzed. They hereby test the validity of their diffusion model.

• OSTI ID: 5834632
• Journal Information: Journal of Geophysical Research; (USA), Journal Name: Journal of Geophysical Research; (USA) Vol. 94:A7; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANISOTROPY
BARYONS
CALCULATION METHODS
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HYDROMAGNETIC WAVES
INTERPLANETARY MAGNETIC FIELDS
INTERPLANETARY SPACE
MAGNETIC FIELDS
MAGNETOACOUSTIC WAVES
MATHEMATICAL MODELS
MEAN FREE PATH
NUCLEONS
NUMERICAL SOLUTION
PROTONS
RADIATIONS
SCATTERING
SHOCK WAVES
SOLAR ACTIVITY
SOLAR PARTICLES
SOLAR PROTONS
SOLAR RADIATION
SOLAR WIND
SPACE
STELLAR RADIATION
TESTING
VALIDATION