Speaker
Mr
Jörn Warnecke
(Nordita)
Description
Magnetic buoyancy is believed to drive the transport of
magnetic flux tubes from the convection zone to the surface
of the Sun. The magnetic fields form twisted loop-like
structures in the solar atmosphere. In this paper we use
helical forcing to produce a large-scale dynamo-generated
magnetic field, which rises even without magnetic buoyancy.
A two layer system is used as computational domain where the
upper part represents the solar atmosphere. Here, the
evolution of the magnetic field is solved with the
stress--and--relax method. Below this region a magnetic
field is produced by a helical forcing function in the
momentum equation, which leads to dynamo action. We find
twisted magnetic fields emerging frequently to the outer
layer, forming arch-like structures. In addition, recurrent
plasmoid ejections can be found by looking at space--time
diagrams of the magnetic field. Recent simulations in
spherical coordinates show similar results.
