Theory of magnetic reconnection in solar and astrophysical plasmas
Pontin, D. I., Theory of magnetic reconnection in solar and astrophysical plasmas, Philosophical Transactions of the Royal Society of London Series A, 370, 3169-3192 (2012) (ADS)
(click on the image for a larger version)
The basic spine-and-fan geometry of the magnetic field at a null point,
as also shown in a very early
cartoon here in the Archive.
The abstract of this nice review paper expounds the generally heard
description that magnetic reconnection expresses energy release from
the field by a change in its topology (the spine line and fan surfaces
are loci of field-line singularities).
Is this really true?
Does inductive energy release have
to change the topology of a magnetic field?
One can add energy to a magnetic field by simply cranking a rheostat,
which changes the geometry of the field (it gets bigger) but not its
topology (it's a dipole and has no nulls).
So this basic viewpoint seems questionable, even though null points
clearly occur in nature and also may have something to do with the
observational signatures of energy release.
So... geometry or topology... must reserve judgement...
The basic spine-and-fan geometry of the magnetic field at a null point, as also shown in a very early cartoon here in the Archive. The abstract of this nice review paper expounds the generally heard description that magnetic reconnection expresses energy release from the field by a change in its topology (the spine line and fan surfaces are loci of field-line singularities). Is this really true? Does inductive energy release have to change the topology of a magnetic field? One can add energy to a magnetic field by simply cranking a rheostat, which changes the geometry of the field (it gets bigger) but not its topology (it's a dipole and has no nulls). So this basic viewpoint seems questionable, even though null points clearly occur in nature and also may have something to do with the observational signatures of energy release. So... geometry or topology... must reserve judgement...