Rigorous new limits on magnetic helicity dissipation in the solar corona
作者:
MitchellA. Berger,
期刊:
Geophysical & Astrophysical Fluid Dynamics
(Taylor Available online 1984)
卷期:
Volume 30,
issue 1-2
页码: 79-104
ISSN:0309-1929
年代: 1984
DOI:10.1080/03091928408210078
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
The Cauchy-Schwarz inequality is employed to find geometry-independent limits on the magnetic helicity dissipation rate in a resistive plasma. These limits only depend upon the total energy of the plasma, the energy dissipation rate, and a mean diffusion coefficient. For plasmas isolated from external energy sources, limits can also be set on the minimum time necessary to dissipate a net amount of helicity ΔH. As evaluated in the context of a solar coronal loop, these limits strongly suggest that helicity decay occurs on a diffusion timescale which is far too great to be relevant to most coronal processes. Furthermore, rapid reconnection is likely to approximately conserve magnetic helicity. The dilliculties involved in determining the free energy residing in a magnetic structure (given the constraint of magnetic helicity conservation) are discussed.
点击下载:
PDF (996KB)
返 回