Effect of a guide field on the turbulence like properties of magnetic reconnection

TL;DR

This study investigates how an external guide field influences the turbulence-like properties of magnetic reconnection through kinetic simulations, revealing consistent spectral behaviors and energy transfer characteristics akin to turbulence.

Contribution

It demonstrates that the turbulence-like energy spectrum and transfer in magnetic reconnection are similar to turbulence, regardless of the guide field strength, using comprehensive PIC simulations and theoretical analysis.

Findings

Magnetic energy spectrum follows a -5/3 slope in the inertial range, unaffected by guide field.

Electric field spectrum steepens with guide field, approaching -5/3 slope.

Energy transfer behavior remains consistent across different guide fields, indicating turbulence-like energy cascade.

Abstract

The effect of an external guide field on the turbulence-like properties of magnetic reconnection is studied using five different 2.5D kinetic particle-in-cell (PIC) simulations. The magnetic energy spectrum is found to exhibit a slope of approximately -5/3 in the inertial range, independent of the guide field. On the contrary, the electric field spectrum, in the inertial range steepens more with the guide field and approaches a slope of -5/3. In addition, spectral analysis of the different terms of the generalized Ohm's law is performed and found to be consistent with PIC simulations of turbulence and MMS observations. Finally, guide field effect on the energy transfer behavior is examined using von-K\'arm\'an Howarth (vKH) equation based on incompressible Hall-MHD. The general characteristics of the vKH equation with constant rate of energy transfer in the inertial range, is consistent in all the simulations. This suggests that the qualitative behavior of energy spectrum, and energy transfer in reconnection is similar to that of turbulence, indicating that reconnection fundamentally involves an energy cascade.