Reconnection and the ideal evolution of magnetic fields

Area of Science:

• Plasma physics
• Magnetohydrodynamics
• Astrophysical dynamics

Background:

• Ideal magnetic field evolution in conducting fluids is governed by Faraday's law.
• This ideal state requires the parallel electric field to be a scalar potential derivative.
• Magnetic reconnection occurs when this scalar potential does not exist.

Purpose of the Study:

• Investigate the conditions for ideal magnetic field evolution.
• Analyze the role of scalar potentials in magnetic reconnection.
• Contrast reconnection mechanisms in periodic systems versus astrophysical contexts.

Main Methods:

• Analysis of Faraday's law in conducting fluids.
• Examination of scalar potential conditions for ideal evolution.
• Theoretical analysis of magnetic field line topology.

Main Results:

• Ideal magnetic evolution holds when the parallel electric field is a scalar potential derivative.
• Reconnection is necessitated by the absence of such a potential.
• In 2D periodic systems, reconnection localizes to rational surfaces where field lines close.

Conclusions:

• The rational surface effect in periodic simulations is an artifact of the chosen boundary conditions.
• Astrophysical reconnection likely occurs through different mechanisms not captured by simple periodic models.
• Further research is needed to understand astrophysical reconnection drivers.