Identification of intermittent multi-fractal turbulence in fully kinetic simulations of magnetic reconnection

TL;DR

This paper analyzes fully kinetic simulations of magnetic reconnection, revealing that the magnetic field fluctuations exhibit multifractal, anisotropic turbulence with non-Gaussian distributions, extending turbulence concepts to collisionless plasma reconnection.

Contribution

It demonstrates that magnetic reconnection involves intermittent, multifractal turbulence on kinetic scales, linking collisionless dissipation to fluid turbulence phenomenology.

Findings

Magnetic field fluctuations are anisotropic and multifractal.

Field J.E also exhibits multifractality, indicating intermittent energy conversion.

Reconnection turbulence shows non-Gaussian distributions and Extended Self-Similarity.

Abstract

Recent fully nonlinear, kinetic three-dimensional simulations of magnetic reconnection [Daughton et al. 2011] evolve structures and exhibit dynamics on multiple scales, in a manner reminiscent of turbulence. These simulations of reconnection are among the first to be performed at sufficient spatio-temporal resolution to allow formal quantitative analysis of statistical scaling which we present here. We find that the magnetic field fluctuations generated by reconnection are anisotropic, have non-trivial spatial correlation and exhibit the hallmarks of finite range fluid turbulence; they have non-Gaussian distributions, exhibit Extended Self-Similarity in their scaling and are spatially multifractal. Furthermore, we find that the field J.E is also multifractal, so that magnetic energy is converted to plasma kinetic energy in a manner that is spatially intermittent. This suggests that dissipation in this sense in collisionless reconnection on kinetic scales has an analogue in fluid-like turbulent phenomenology, in that it proceeds via multifractal structures generated by an intermittent cascade.