Forced 3D Reconnection in an Exponentially Separating Magnetic Field

Area of Science:

• Plasma Physics
• Astrophysical Plasmas
• Fusion Energy

Background:

• Magnetic reconnection is a fundamental process in plasma physics, crucial for energy release in astrophysical phenomena and fusion devices.
• Understanding the dynamics of 3D magnetic reconnection in sheared magnetic fields is essential for predicting plasma behavior.

Purpose of the Study:

• To investigate a solvable scenario for 3D magnetic reconnection in a sheared magnetic field.
• To determine the reconnection timescales under different physical regimes (MHD and semicollisional electron-only).
• To analyze the influence of magnetic field line separation on reconnection rates.

Main Methods:

• A localized external force was applied to a flux tube to generate Alfvénic perturbations.
• Analysis of magnetic diffusion enhancement due to reduced perturbation scales across separated field lines.
• Derivation of reconnection timescales for magnetohydrodynamics (MHD) and semicollisional electron-only models.

Main Results:

• Reconnection timescale is proportional to S/lnS in MHD and S^{1/3} for semicollisional electron-only reconnection, where S is the Lundquist number.
• The semicollisional reconnection rate was found to be independent of magnetic geometry.
• Slower field-line separation was shown to increase the reconnection rate in the MHD regime.

Conclusions:

• The study provides a detailed analysis of 3D magnetic reconnection in sheared fields with varying physical conditions.
• Findings offer insights into controlling reconnection rates, relevant for both astrophysical simulations and fusion energy research.
• The geometry-independent nature of semicollisional reconnection simplifies its application to diverse plasma environments.