Linear Evolution of Current Sheets in Sheared Force-Free Magnetic Fields with Discontinuous Connectivity

  1. C. T. Russell,
  2. E. R. Priest and
  3. L. C. Lee
  1. Richard Wolfson

Published Online: 21 MAR 2013

DOI: 10.1029/GM058p0263

Physics of Magnetic Flux Ropes

Physics of Magnetic Flux Ropes

How to Cite

Wolfson, R. (1990) Linear Evolution of Current Sheets in Sheared Force-Free Magnetic Fields with Discontinuous Connectivity, in Physics of Magnetic Flux Ropes (eds C. T. Russell, E. R. Priest and L. C. Lee), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM058p0263

Author Information

  1. Department of Physics, Middlebury College, Middlebury, VT 05753

Publication History

  1. Published Online: 21 MAR 2013
  2. Published Print: 1 JAN 1990

ISBN Information

Print ISBN: 9780875900261

Online ISBN: 9781118663868

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Keywords:

  • Solar photosphere;
  • Magnetic flux;
  • Astrophysics

Summary

The formation of thin current sheets in tenuous, magnetized plasma may be an important mechanism for the buildup and subsequent release of energy in astrophysical situations, especially in the solar corona. Such sheets might arise from the random but continuous motion of magnetic footpoints associated, for example, with photospheric velocity fields. Whether such sheets can form when all features of the magnetic and velocity fields are strictly continuous remains controversial. However, current sheet formation in situations incorporating some sort of discontinuity in field line connectivity is expected, although few quantitative examples exist. This paper develops a model for studying the quasistatic evolution of current sheets due to shearing of footpoints in a highly idealized geometry incorporating an abrupt jump in field line connectivity. Although the model is limited to the linear regime in which the field deviates only slightly from its initial potential state, it nevertheless shows clearly the formation of thin current layers, and permits surprisingly large shearing motions before the linear approximation is violated. Finally, calculations of energy buildup, scaled to the size of a typical solar flare region, show that excess energy comparable to that released in a flare can be stored in the sheared field.