Magnetic reconnection as an energy cascade process

TL;DR

This study demonstrates that magnetic reconnection functions as an energy cascade process, with energy transfer characteristics similar to turbulence, supported by kinetic simulations and theoretical analysis of Hall magnetohydrodynamics.

Contribution

The paper provides the first explicit evidence linking magnetic reconnection to the energy cascade process through simulation and theoretical analysis.

Findings

Energy transfer decomposition is structurally similar in reconnection and turbulence.

Reconnection rate correlates with the energy transfer evolution.

Reconnection is fundamentally an energy cascade process.

Abstract

Reconnection and turbulence are two of the most commonly observed dynamical processes in plasmas, but their relationship is still not fully understood. Using 2.5D kinetic particle-in-cell simulations of both strong turbulence and reconnection, we compare the cross-scale transfer of energy in the two systems by analyzing the generalization of the von K\'arm\'an Howarth equations for Hall magnetohydrodynamics, a formulation that subsumes the third-order law for steady cascade rates. Even though the large scale features are quite different, the finding is that the decomposition of the energy transfer is structurally very similar in the two cases. In the reconnection case, the time evolution of the energy transfer also exhibits a correlation with the reconnection rate. These results provide explicit evidence that reconnection itself is fundamentally an energy cascade process.