Nonlinear Structure of Super‐Thin Current Sheets With Guide Field: Equilibrium or Dynamic?

Abstract 1D self‐consistent model of super‐thin current sheet (STCS) based both on a quasi‐adiabatic approach for the demagnetized proton and electron motion is generalized to the case of configuration with non‐zero guide field. The part of electron population is supposed to be magnetized (described via guiding center approximation). The magnetic field configuration includes three components: self‐consistent and components maintained by current components and respectively, plus a constant component in GSM coordinates. We constructed a transition from intense STCSs supported by quasi‐adiabatic electrons with high velocity anisotropy to less intense and thicker current sheets (CSs) supported by magnetized electrons with pressure anisotropy as the guide field increases and the system equilibrium approaches a force‐free configuration. Our model is capable to describe two distinct regimes: (a) intense STCSs supported by demagnetized electrons with a weak guide field (, where is the magnetic field amplitude at the CS edge), and (b) quasi‐force‐free configurations with a strong guide field . Analysis of 181 STCS crossings by MMS spacecrafts reveals a critical discrepancy. For a strong guide field, the modeled stationary configurations of electron CSs broaden and weaken, in contrast to the observed CSs, which remain super‐thin, exhibit clear non‐stationarity and are accompanied by the generation of a strong electric field.