Interacting tilt and kink instabilities in repelling current channels
Abstract
I present a numerical study in resistive magnetohydrodynamics where the initial equilibrium configuration contains adjacent, oppositely directed current channels. Since oppositely directed current channels repel, the equilibrium is liable to an ideal magnetohydrodynamic tilt instability. This tilt evolution in planar settings involves two magnetic islands, which on Alfvenic timescales undergo a combined rotation and displacement. This deformation leads to the creation of (near) singular current layers, posing severe challenges to numerical approaches. Using our open-source grid-adaptive MPI-AMRVAC software, we revisit the planar evolution case in compressible MHD, as well as its extension to 2.5D and full 3D scenarios. As long as the third dimension is ignorable, pure tilt evolutions result which are hardly affected by an added perpendicular magnetic field component. In all 2.5D runs, our simulations show evidence for secondary tearing type disruptions throughout the near singular current sheets. In full 3D, both current channels can be liable to additional ideal kink deformations. We discuss the effects of having both kink and tilt instabilities acting simultaneously in the violent, reconnection dominated evolution. Possible laboratory as well as space plasma applications will briefly be discussed.
- Publication:
-
40th COSPAR Scientific Assembly
- Pub Date:
- 2014
- Bibcode:
- 2014cosp...40E1453K