The formation and decay of thin current sheets (TCSs; e.g., Baumjohann et al., 2007 and references therein) are important constituents of the energy transformation in the Earth's magnetotail (e.g., Angelopoulos et al., 2008;Lui et al., 2008;Sergeev et al., 2012). It has been shown that, the TCSs with L ≤ ρ P (ρ P is a gyroradius of thermal protons) are often observed in the near-Earth tail during the growth phase of substorm (e.g.,

Thin current sheets (TCSs) are the key structures in space and laboratory plasmas responsible for the accumulation and subsequent release of the stored magnetic energy. Spacecraft measurements in the near Earth's space revealed the complicated multilayer TCSs structure consisting from extremely thin and strong electron current embedded inside the thicker ion current layer. In this paper we present for the first time the analytical self‐consistent model of 1D super thin electron current sheet (STCS) supported by magnetized electrons within a much wider (but still very thin) proton structure carried by nonmagnetized (quasi‐adiabatic) particles. We take into account the dependence of electron STCS on anisotropy of electron distribution and magnetic field shear often existing in realistic TCS configurations. It is shown that the structure of the embedded STCS can be described by the simple nonlinear equation, which allows to estimate the scaling of STCS thickness due to coupling of electron and ion domains, although electron dynamics described by guiding center drift approximation is scale free. The theoretical results are in a good agreement with MMS spacecraft observations in the Earth's magnetotail.

Recent MMS observations confirmed the existence of the quasi‐stationary electron‐scale super‐thin current sheets (STCSs) with a half‐thickness of few electron gyroradii. STCSs contain the electron population consisting of magnetized and demagnetized particles. To study the role of the demagnetized electrons, we developed a self‐consistent combined model of a STCS in which the dynamics of a part of the electron population is described by the quasi‐adiabatic approximation, while the motion of the other part is described by the guiding center approximation. Demagnetized ion population can be described in a frame of quasi‐adiabatic approach. In the presented model we introduced the weight coefficient of the demagnetized electron plasma density χ depending on the magnetic field normal component Bn/B0 and compared the characteristic profiles of two STCSs differing by the presence (χ ≠ 0) and absence (χ = 0) of demagnetized electrons. It is shown that the presence of demagnetized electrons makes the current density profile of STCS significantly more intense and narrower. The thickness and intensity of STCS depend on the anisotropy coefficient of magnetized electrons and the incoming drift velocity of demagnetized electrons. The maximum current density continuously increases with the growth of the demagnetized electron population and is controlled by the ratio of the thermal to the incoming drift electron velocities. Thus intense current sheets can be formed even in the absence of strong electron anisotropy, which is confirmed by MMS observations.

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