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Title: STRAHL FORMATION IN THE SOLAR WIND ELECTRONS VIA WHISTLER INSTABILITY

This Letter puts forth a possible explanation for the formation of a solar wind strahl electron distribution function by means of local wave–particle interactions. A solar wind electron consists of a core and the hot “halo” electrons, which possess a net drift speed with respect to the core. According to the present model, pitch angle scattering of the initially isotropic drifting halo occurs when the enhanced whistler waves are excited by mildly anisotropic core electrons. The pitch angle scattering primarily affects the halo moving in the anti-sunward direction, resulting in pitch angle diffusion across the 90° gap through a nonlinear scattering process, and consequently leading to a reduction in the net drift speed of halo electrons. The remaining portion of the anti-sunward moving halo, which is not affected by pitch angle scattering, simply appears to form a field-aligned strahl in the electron velocity distribution. The present scenario of local generation of the strahl is demonstrated by the particle-in-cell simulation.
Authors:
;  [1] ;  [2] ;  [3]
  1. Faculty of Human Development, University of Toyama, 3190, Gofuku, Toyama City, Toyama 930-8555 (Japan)
  2. Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742 (United States)
  3. Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya 464-8601 (Japan)
Publication Date:
OSTI Identifier:
22518887
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 811; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANISOTROPY; COMPUTERIZED SIMULATION; DIFFUSION; DISTRIBUTION FUNCTIONS; INCLINATION; NONLINEAR PROBLEMS; PLASMA; SCATTERING; SOLAR ELECTRONS; SOLAR WIND; WHISTLER INSTABILITY