In this work, we investigated the influence of different ion-to-electron temperature ratio τ on reconnection and on the resulting subion-scale turbulence in a low-βe collisionless plasma (Granier et al. 2024). Note that observations have revealed that, in most astrophysical plasmas, ion temperatures are usually larger than those of electrons, with for example τ ≳ 10 in the Earth’s magnetosphere, τ ∼ 3 − 4 in the Earth’s magnetosheath and τ ∼ 2 in the solar wind. At large ion-to-electron temperature ratio, the development of the tearing mode is so rapid that shear flows develop around the magnetic island, leading to turbulence triggered by Kelvin-Helmoltz instabilities.
Turbulence spreading outside the separatrices due to secondary instabilities.A velocity shear along the magnetic field line triggers the fluid instability. The magnetic field lines become distorted and stretched in the direction of the shear. At a latter time, as the fluid is twisting, small magnetic eddies are formed due to magnetic reconnection at the separatrices.Vorticity of electron fluid depicting the onset of Kelvin-Helmholtz instability and the formation of two magnetic vortices after the reconnection of black-dashed magnetic field lines.
