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Title: REDUCTION OF DRIFT EFFECTS DUE TO SOLAR WIND TURBULENCE

Gradient and curvature drift play a key role in the modulation of cosmic rays. Reduction in the drift coefficient due to turbulence has been demonstrated unambiguously through direct numerical simulations, but a theory that can explain these results is still lacking. We introduce a parameterized form of the drift coefficient based on direct numerical simulations and show that good agreement with observed proton energy spectra at Earth can be found when it is used in a numerical modulation model. We show that the turbulence ultrascale, for which no observations currently exist, plays an important role in drift reduction. The magnitude at Earth and spatial dependence of this quantity required to fit cosmic-ray observations at Earth are argued to be plausible based on the required properties of the two-dimensional turbulence spectrum at large scales.
Authors:
;  [1]
  1. Unit for Space Physics, North-West University, 2520 Potchefstroom (South Africa)
Publication Date:
OSTI Identifier:
21474359
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 725; Journal Issue: 1; Other Information: DOI: 10.1088/0004-637X/725/1/1366
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPUTERIZED SIMULATION; COSMIC RADIATION; ENERGY SPECTRA; HELIOSPHERE; PROTONS; SOLAR WIND; SPACE DEPENDENCE; SUN; TURBULENCE ATMOSPHERES; BARYONS; ELEMENTARY PARTICLES; FERMIONS; HADRONS; IONIZING RADIATIONS; MAIN SEQUENCE STARS; NUCLEONS; RADIATIONS; SIMULATION; SOLAR ACTIVITY; SOLAR ATMOSPHERE; SPECTRA; STARS; STELLAR ACTIVITY; STELLAR ATMOSPHERES; STELLAR WINDS