# Role of reconnection in inertial kinetic-Alfven turbulence

## TL;DR

This paper investigates how reconnection influences inertial kinetic-Alfvén turbulence, revealing the formation of thin current sheets, their aspect ratios limited by tearing instability, and resulting energy spectra and anisotropy in low-beta plasmas.

## Contribution

It introduces a model linking reconnection-driven current sheet formation to turbulence spectra and anisotropy at kinetic scales in inertial kinetic-Alfvén turbulence.

## Key findings

- Eddy structures organize into thin current sheets constrained by tearing instability.
- The energy spectrum ranges from $k^{-8/3}$ to $k^{-3}$ depending on conditions.
- Spectral anisotropy varies with scale, from $k_z extless extless k_ot^{2/3}$ to $k_z extless extless k_ot$.

## Abstract

In a weakly collisional, low-electron-beta plasma, large-scale Alfv\'en turbulence transforms into inertial kinetic-Alfv\'en turbulence at scales smaller than the ion microscale (gyroscale or inertial scale). We propose that at such kinetic scales, the nonlinear dynamics tend to organize turbulent eddies into thin current sheets, consistent with the existence of two conserved integrals of the ideal equations, energy and helicity. The formation of strongly anisotropic structures is arrested by the tearing instability that sets a critical aspect ratio of the eddies at each scale $a$ in the plane perpendicular to the guide field. This aspect ratio is defined by the balance of the eddy turnover rate and the tearing rate, and varies from $(d_e/a)^{1/2}$ to $d_e/a$ depending on the assumed profile of the current sheets. The energy spectrum of the resulting turbulence varies from $k^{-8/3}$ to $k^{-3}$, and the corresponding spectral anisotropy with respect to the strong background magnetic field from $k_z\lesssim k_\perp^{2/3}$ to $k_z\lesssim k_\perp$.