Reconnection and Non-Ideal Behaviour at 3D Magnetic Null Points
Abstract
The evolution of the magnetic field in the vicinity of three-dimensional magnetic null points---thought to be present in abundance in the complex field of the Solar corona---is discussed, with reference to the possibility that reconnection might occur there. It is shown that in the framework of ideal MHD, certain evolutions of the null point are prohibited, specifically, evolutions which cause the ratios of the null point eigenvalues to change in time. Particular analytical kinematic examples are discussed which demonstrate that in the ideal limit, physical quantities are not smooth at the null point spine and fan when such an evolution occurs. Simulations of the full resistive MHD equations are then presented. The simulations demonstrate that typical perturbations of a 3D magnetic null point inevitably cause the null point to evolve in the very way that is excluded under the ideal evolution. It is demonstrated that the changing eigenvalue ratio is linked to a growth of electic current, as well as a component of the electric field parallel to the magnetic field, at the null. This parallel electric field is a signal of the breakdown of ideal MHD, and of magnetic reconnection. Implications for coronal heating will be discussed. This work is supported by the NSF and the DOE.
- Publication:
-
AAS/Solar Physics Division Meeting #37
- Pub Date:
- June 2006
- Bibcode:
- 2006SPD....37.1007P