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Title: Spontaneous magnetic reconnection in a turbulent plasma

Abstract

The effects of turbulence are examined in a variety of forms and strengths, on the resistive tearing instability (spontaneous reconnection) in an unstable, sheared-field, resistive-MHD plasma. Both periodic and nonperiodic background fields are modeled. Calculational techniques include a true spectral, or Galerkin-type, algorithm, and a finite-grid alternating direction-implicit method with variable grid spacing. All calculations are fully nonlinear. The tearing mode is found to arise from an initial random turbulent, excitation of fairly general form. This has various implications for solar corona physics (where it increases the likelihood of tearing in situations such as active coronal loops) and for laboratory plasma physics (since it implies that large-scale disruptions can evolve from small-scale turbulence). It also demonstrates that tearing can grow to dominate other forms of reconnection. In studying the effects of ongoing turbulence, it is found that although brief disturbances have little of no effect on tearing modes, continual stirring of background turbulence results in a modest enhancement of the tearing-mode growth rate (by a factor of perhaps two or three). This enhancement is the correct direction, but great enough by itself, to help explain the observed short coronal-loop-to-flare conversion time scales. The simulations demonstrate the Alfven effect, an equipartitionmore » between magnetic and kinetic turbulence energy, and that there is a dynamic mechanism serving to maintain this balance. There are however notable exceptions to this condition.« less

Authors:
Publication Date:
Research Org.:
California Univ., Irvine, CA (USA)
OSTI Identifier:
6747055
Resource Type:
Miscellaneous
Resource Relation:
Other Information: Ph.D. Thesis
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; MAGNETIC RECONNECTION; COMPUTERIZED SIMULATION; PLASMA INSTABILITY; SOLAR CORONA; MAGNETIC FIELDS; ALGORITHMS; SOLAR FLARES; THEORETICAL DATA; TURBULENCE; ATMOSPHERES; DATA; INFORMATION; INSTABILITY; MATHEMATICAL LOGIC; NUMERICAL DATA; SIMULATION; SOLAR ACTIVITY; STELLAR ATMOSPHERES; STELLAR CORONAE; 640104* - Astrophysics & Cosmology- Solar Phenomena; 700103 - Fusion Energy- Plasma Research- Kinetics

Citation Formats

Deeds, D A. Spontaneous magnetic reconnection in a turbulent plasma. United States: N. p., 1989. Web.
Deeds, D A. Spontaneous magnetic reconnection in a turbulent plasma. United States.
Deeds, D A. Sun . "Spontaneous magnetic reconnection in a turbulent plasma". United States.
@article{osti_6747055,
title = {Spontaneous magnetic reconnection in a turbulent plasma},
author = {Deeds, D A},
abstractNote = {The effects of turbulence are examined in a variety of forms and strengths, on the resistive tearing instability (spontaneous reconnection) in an unstable, sheared-field, resistive-MHD plasma. Both periodic and nonperiodic background fields are modeled. Calculational techniques include a true spectral, or Galerkin-type, algorithm, and a finite-grid alternating direction-implicit method with variable grid spacing. All calculations are fully nonlinear. The tearing mode is found to arise from an initial random turbulent, excitation of fairly general form. This has various implications for solar corona physics (where it increases the likelihood of tearing in situations such as active coronal loops) and for laboratory plasma physics (since it implies that large-scale disruptions can evolve from small-scale turbulence). It also demonstrates that tearing can grow to dominate other forms of reconnection. In studying the effects of ongoing turbulence, it is found that although brief disturbances have little of no effect on tearing modes, continual stirring of background turbulence results in a modest enhancement of the tearing-mode growth rate (by a factor of perhaps two or three). This enhancement is the correct direction, but great enough by itself, to help explain the observed short coronal-loop-to-flare conversion time scales. The simulations demonstrate the Alfven effect, an equipartition between magnetic and kinetic turbulence energy, and that there is a dynamic mechanism serving to maintain this balance. There are however notable exceptions to this condition.},
doi = {},
url = {https://www.osti.gov/biblio/6747055}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1989},
month = {1}
}

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