Magnetohydrodynamic Turbulent Cascade of Coronal Loop Magnetic Fields

TL;DR

This study uses high-resolution simulations to explore the turbulent cascade of magnetic fields in coronal loops, revealing a magnetic energy-dominated inertial range with reconnection-driven dynamics similar to standard MHD turbulence.

Contribution

It demonstrates that magnetic reconnection significantly influences the turbulent cascade in coronal loops, aligning with MHD turbulence characteristics despite boundary-driven reconnection.

Findings

Magnetic energy spectrum follows a k_perp^{-2.7} scaling.

Velocity fluctuations scale as ^{+0.2}, indicating increased small-scale activity.

Reconnection plays a key role in the turbulent energy transfer process.

Abstract

The Parker model for coronal heating is investigated through a high resolution simulation. An inertial range is resolved where fluctuating magnetic energy E_M (k_perp) \propto k_\perp^{-2.7} exceeds kinetic energy E_K (k_\perp) \propto k_\perp^{-0.6}. Increments scale as \delta b_\ell \simeq \ell^{-0.85} and \delta u_\ell \simeq \ell^{+0.2} with velocity increasing at small scales, indicating that magnetic reconnection plays a prime role in this turbulent system. We show that spectral energy transport is akin to standard magnetohydrodynamic (MHD) turbulence even for a system of reconnecting current sheets sustained by the boundary. In this new MHD turbulent cascade, kinetic energy flows are negligible while cross-field flows are enhanced, and through a series of "reflections" between the two fields, cascade more than half of the total spectral energy flow.