Stability of the Magnetotail Current Sheet With Normal Magnetic Field and Field‐Aligned Plasma Flows. Issue 11 (10th November 2021)

• Record Type: Journal Article
• Authors: Shi, Chen; Artemyev, Anton; Velli, Marco; Tenerani, Anna
• Is Part Of: Journal of geophysical research. Volume 126:Issue 11(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-11-10
• Subjects: substorm -- current sheet -- tearing instability -- magnetic reconnection; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2021JA029711
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: One of the most important problems of magnetotail dynamics is the substorm onset and the related instability of the magneotail current sheet. Since the simplest 2D current sheet configuration with monotonic B z was proven to be stable to the tearing mode, the focus of the instability investigation moved to more specific configurations, for example, kinetic current sheets with strong transient ion currents and current sheets with non‐monotonic B z (local B z minima or/and peaks). The stability of the latter current sheet configuration has been studied both within kinetic and fluid approaches, whereas the investigation of the transient ion effects was limited to kinetic models only. This paper aims to provide a detailed analysis of the stability of a multi‐fluid current sheet configuration that mimics current sheets with transient ions. Using the system with two field‐aligned ion flows that mimic the effect of pressure non‐gyrotropy, we construct a 1D current sheet with a finite B z . This model describes well recent findings of very thin intense magnetotail current sheets. The stability analysis of this two‐ion model confirms the stabilizing effect of finite B z and shows that the most stable current sheet is the one with exactly counter‐streaming ion flows and zero net flow. Such field‐aligned flows may substitute the contribution of the pressure tensor nongyrotropy to the stress balance but cannot overtake the stabilizing effect of B z . Obtained results are discussed in the context of magnetotail dynamical models and spacecraft observations. Key Points: 1D magnetotail current sheet model with a finite B z and plasma flows is developed Strong stabilizing effect of B z is confirmed for current sheets with field aligned flow Field‐aligned plasma flows cannot overtake the B z stabilizing effect