Energy-crossing number relations for braided magnetic fields
- 8 February 1993
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 70 (6) , 705-708
- https://doi.org/10.1103/physrevlett.70.705
Abstract
This Letter derives lower bounds on the energy of braided magnetic fields, based on crossing number techniques pioneered by Freedman and He. Mean crossing numbers are defined for magnetic fields inside a cylinder; for configurations with a uniform axial component the square of the crossing number provides a lower bound for the free magnetic energy. An energy-crossing number relation is also derived for a random field with Gaussian amplitude distribution, in the limit of small correlation lengths. These results provide information on the structure of solar coronal loops and on the problem of coronal heating.Keywords
This publication has 7 references indexed in Scilit:
- Third-order braid invariantsJournal of Physics A: General Physics, 1991
- Nanoflares and the solar X-ray coronaThe Astrophysical Journal, 1988
- Cascade of magnetic energy as a mechanism of coronal heatingThe Astrophysical Journal, 1986
- Electric currents in the solar corona and the existence of magnetostatic equilibriumThe Astrophysical Journal, 1985
- The topological properties of magnetic helicityJournal of Fluid Mechanics, 1984
- Magnetic Neutral Sheets in Evolving Fields - Part Two - Formation of the Solar CoronaThe Astrophysical Journal, 1983
- Coronal heating by stochastic magnetic pumpingThe Astrophysical Journal, 1981