Description
It is well known that the magnetic helicity integral of magnetohydrodynamics is non-unique if the magnetic field passes through the domain boundary. In particular, it depends on the choice of vector potential. In some sense, any choice is equally meaningful, because all are invariant under ideal deformations vanishing on the boundary. However, we propose that some choices are more physically meaningful than others, if one wishes to measure topological complexity of the magnetic field. For the particular case of a spherical shell domain – motivated by the Sun’s atmosphere – I will outline how several desirable properties point to a particular choice of vector potential.
Authors
Anthony Yeates
(Durham University)
Christopher Prior
(Durham University)
