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Title: Cross-field diffusion of energetic (100 keV to 2 MeV) protons in interplanetary space

Magnetic field magnitude decreases (MDs) are observed in several regions of the interplanetary medium. In this paper, we characterize MDs observed by the Ulysses spacecraft instrumentation over the solar south pole by using magnetic field data to obtain the empirical size, magnetic field MD, and frequency of occurrence distribution functions. The interaction of energetic (100 keV to 2 MeV) protons with these MDs is investigated. Charged particle and MD interactions can be described by a geometrical model allowing the calculation of the guiding center shift after each interaction. Using the distribution functions for the MD characteristics, Monte Carlo simulations are used to obtain the cross-field diffusion coefficients as a function of particle kinetic energy. It is found that the protons under consideration cross-field diffuse at a rate of up to ≈11% of the Bohm rate. The same method used in this paper can be applied to other space regions where MDs are observed, once their local features are well known.
Authors:
 [1] ;  [2] ; ;  [3] ;  [4]
  1. Instituto Federal de Minas Gerais-IFMG, Ouro Preto, MG, 35400-000 (Brazil)
  2. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
  3. Instituto Nacional de Pesquisas Espaciais-INPE, São José dos Campos, SP, 12227-010 (Brazil)
  4. Indian Institute for Geomagnetism, Navi Mumbai 410 218 (India)
Publication Date:
OSTI Identifier:
22341909
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 778; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CHARGED PARTICLES; COMPUTERIZED SIMULATION; DATA ANALYSIS; DIFFUSION; DISTRIBUTION FUNCTIONS; HELIOSPHERE; INTERACTIONS; INTERPLANETARY SPACE; KEV RANGE; MAGNETIC FIELDS; MEV RANGE; MONTE CARLO METHOD; PROTONS; SUN