Regularized BiotSavart Laws for Modeling Magnetic Flux Ropes 

Viacheslav S. Titov Submitted: 20171222 13:47
Many existing models assume that magnetic flux ropes play a key role in solar flares and coronal mass ejections (CMEs). It is therefore important to develop efficient methods for constructing fluxrope configurations constrained by observed magnetic data and the morphology of the preeruptive source region. For this purpose, we have derived and implemented a compact analytical form that represents the magnetic field of a thin flux rope with an axis of arbitrary shape and circular crosssections. This form implies that the flux rope carries axial current I and axial flux F, so that the respective magnetic field is the curl of the sum of axial and azimuthal vector potentials proportional to I and F, respectively. We expressed the vector potentials in terms of modified BiotSavart laws whose kernels are regularized at the axis in such a way that, when the axis is straight, these laws define a cylindrical forcefree flux rope with a parabolic profile for the axial current density. For the cases we have studied so far, we determined the shape of the rope axis by following the polarity inversion line of the eruptions' source region, using observed magnetograms. The height variation along the axis and other fluxrope parameters are estimated by means of potential field extrapolations. Using this heuristic approach, we were able to construct preeruption configurations for the 2009 February 13 and 2011 October 1 CME events. These applications demonstrate the flexibility and efficiency of our new method for energizing preeruptive configurations in simulations of CMEs.
Authors: Viacheslav S. Titov, Cooper Downs, Zoran Mikić, Tibor Török, Jon A. Linker and Ronald M. Caplan
Projects: None

Publication Status: Accepted for publication in ApJL.
Last Modified: 20171224 20:47


