Structure of non-adiabatic current sheets: Role of the trapped population and phase mixing

Self-consistent model of 1D current sheet (CS) enables to explore analytically the properties of equilibrium solutions in dependence on the parameters of the input distributions (e.g. plasma mantle) forming the structure of the magnetic field reversal. Distribution functions depends in this model only on two most natural parameters (integrals or approximate integrals of motion): particle energy W, and quasiadiabatic invariant I-z. There are two topologically disjoint regions in the phase space of nonadiabatic particles: (a) integrable orbits (trapped particles), (b) quasiadiabatic orbits, crossing the separatrix (transient particles). Population (a) in the CS could originate from the sources different from plasma mantle (e.g. LLBL). While the basic structure of CS is formed by paramagnetic currents carried by particles at transient orbits (b), trapped particles (a) might have significant effect on the CS structure. Because this population is phase mixed along the integrable invariant tori, the total cross-tail current carried by trapped particles should be absent. Their pronounced effect is two fold: trapped particles could appeciably reduce the paramagnetic current density near the tail midplane and partially compensate the diamagnetic currents of transient particles at the edges of CS. Considering the amount of trapped particles as a free parameter we study their influence on the characteristic profile of the magnetic field. Sometimes at the edge of CS magnetic field experiences the characteristic overshoot feature, with the amplitude directly related to the plasma content of the trapped domain.