Configuration of magnetotail current sheet prior to magnetic reconnection onset

Abstract

The magnetotail current sheet configuration determines magnetic reconnection properties that control the substorm onset, one of the most energetic phenomena in the Earth's magnetosphere. The quiet-time current sheet is often approximated as a two-dimensional (2D) magnetic field configuration balanced by isotropic plasma pressure gradients. However, reconnection onset is preceded by the current sheet thinning and the formation of a nearly one-dimensional (1D) magnetic field configuration. In this study, using particle-in-cell simulations, we investigate the force balance of such thin current sheets when they are driven by plasma inflow. We demonstrate that the magnetic field configuration transitions from 2D to 1D thanks to the formation of plasma pressure nongyrotropy and reveal its origin in the nongyrotropic terms of the ion distributions. We show that substorm onset may be controlled by the instability and dynamics of such nongyrotropic current sheets, having properties much different from the most commonly investigated 2D isotropic configuration.

arXiv comment16 pages, 4 figures

References in corpus (6)

• Fast Reconnection in High-Lundquist-Number Plasmas Due to Secondary Tearing Instabilities
• Electron-Scale Dynamics of the Diffusion Region during Symmetric Magnetic Reconnection in Space
• Pressure anisotropy and small spatial scales induced by velocity shear
• Pressure anisotropy generation in a magnetized plasma configuration with a shear flow velocity
• Fast inverse transform sampling of non-Gaussian distribution functions in space plasmas
• Suppression of reconnection in polarized, thin magnetotail current sheets: 2D simulations and implications

Cited by in corpus (2)

• Force-free current sheets in the Jovian magnetodisk: the key role of electron field-aligned anisotropy
• Suppression of reconnection in polarized, thin magnetotail current sheets: 2D simulations and implications