Abstract
Abstract. A specific class of solutions of the Vlasov–Maxwell equations, developed by means of generalization of the well-known Harris–Fadeev–Kan–Manankova family of exact two-dimensional equilibria, is studied. The examined model reproduces the current sheet bending and shifting in the vertical plane, arising from the Earth dipole tilting and the solar wind nonradial propagation. The generalized model allows magnetic configurations with equatorial magnetic fields decreasing in a tailward direction as slow as 1∕x, contrary to the original Kan model (1∕x3); magnetic configurations with a single X point are also available. The analytical solution is compared with the empirical T96 model in terms of the magnetic flux tube volume. It is found that parameters of the analytical model may be adjusted to fit a wide range of averaged magnetotail configurations. The best agreement between analytical and empirical models is obtained for the midtail at distances beyond 10–15 RE at high levels of magnetospheric activity. The essential model parameters (current sheet scale, current density) are compared to Cluster data of magnetotail crossings. The best match of parameters is found for single-peaked current sheets with medium values of number density, proton temperature and drift velocity.
Highlights
Studies of magnetosphere dynamics, including substorm events, require a relevant current sheet (CS) stability analysis
A number of such solutions are derived both numerically (e.g., Burkhart et al, 1992; Pritchett and Coroniti, 1992; Cargill et al, 1994, and others) and analytically (e.g., Schindler and Birn, 2002; Yoon and Lui, 2005; Sitnov and Merkin, 2016; Vinogradov et al, 2016). All these solutions describe symmetric planar current sheets; the only approximate equilibrium solution for bent CS was introduced in the paper of Panov et al (2012), where the authors present an analysis of direct THEMIS and GOES observations of plasma sheet evolution near substorm onset
In empirical models (T89, T96, T01, TS05, etc.) magnetic field configurations with any plasma populations are not force-balanced since ∇ × [j × B] = 0, or there is no ∇P to balance Ampere’s force (Zaharia et al, 2003)
Summary
Studies of magnetosphere dynamics, including substorm events, require a relevant current sheet (CS) stability analysis. A number of such solutions are derived both numerically (e.g., Burkhart et al, 1992; Pritchett and Coroniti, 1992; Cargill et al, 1994, and others) and analytically (e.g., Schindler and Birn, 2002; Yoon and Lui, 2005; Sitnov and Merkin, 2016; Vinogradov et al, 2016) All these solutions describe symmetric planar current sheets; the only approximate equilibrium solution for bent CS was introduced in the paper of Panov et al (2012), where the authors present an analysis of direct THEMIS and GOES observations of plasma sheet evolution near substorm onset.
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