A. A. Bykov

Triple splitting of a thin current sheet: A new type of plasma equilibrium

A hybrid numerical model of a one-dimensional current sheet in the Earth’s magnetotail is used to calculate a new self-consistent equilibrium state in the form of a triply split current sheet composed of three thin subsheets that are located close to each other and whose thickness is on the order of the ion gyroradius. The current in the central subsheet flows in the negative direction, opposite to the direction of the currents in the side subsheets. The magnetic field of the triply split current sheet has three neutral planes, in contrast to that of a classical bell-shaped current sheet with a single neutral plane at the sheet center. The particle dynamics in a triply split current configuration is analyzed. It is shown that, within the sheet, the current carriers—untrapped ions—move along meandering trajectories and can maintain an equilibrium structure self-consistently. It is found that a triply split current sheet is stable against external perturbations. The results obtained can help to explain complex dynamic processes occurring in the Earth’s magnetotail.

Forced current sheets in the Earth's magnetotail: Their role and evolution due to nonadiabatic particle scattering

Abstract Current sheets in the Earths magnetosphere may be considered as the regions of the acceleration and heating of solar wind and ionospheric plasmas. We devote our attention to the formation of very thin current sheets (TCSs) in the magnetotail. Various models of TCS equilibrium are discussed. We extend our previous self-consistent analysis of TCS formation. We delineate the relative role of two types of ion populations: (1) current- carrying Speisers ions, impinging from the mantle, (2) nonadiabatic ions resulting from chaotic scattering of ions on transient Speiser-type orbits. To take into account the effect of population (2) we use the centrifugal impulse model, which treats the scattering of the particle magnetic moments as the result of perturbation of the gyromotion by an impulsive centrifugal force. Using several “snapshots” of the scattered distribution function, we obtain a series of quasi-stationary TCS equilibria. It is shown that nonadiabatic effects do not influence significantly the TCS thickness but generally alter the structure of the “young” Speiser-orbit based current sheet, “polluting” the sheet by particles with large magnetic moments, which suppress the positive current in the center of the sheet. In other words, TCS are “aging” due to scattering. When the quasi-trapped population becomes too abundant, the equilibrium solutions decay. The characteristic lifetime of such TCS due to intrinsic nonadiabaticity of the system is found to be about 10–60 minutes.

Influence of Trapped Plasma on the Structure of Collisionless Thin Current Sheets

Using both analytical and numerical models of the collisionless anisotropic current sheet generated by the impinging flows of transient ions, we have studied the self-consistent solutions taking the plasma trapped in the sheet into account. It is demonstrated that there exists a limited “window” in the space of system parameters where self-consistent solutions can exist. When the density of the quasi-trapped plasma is sufficiently large, a redistribution of the total current can be a cause of the sheet decay, when the local current of the trapped particles compensate (totally or in part) the main current in the center and at the edges of the sheet, while the total current generated by ions on the trapped trajectories vanishes.

Neutrino conversions in random magnetic fields and ν ̃ e from the Sun

The magnetic field in the convective zone of the Sun has a random small-scale component with the r.m.s. value substantially exceeding the strength of a regular large-scale field. For two Majorana neutrino flavors

Contrast structures for a quasilinear Sobolev-type equation with unbalanced nonlinearity

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Nonstationary three-dimensional contrasting structures

two helicities in the presence of a neutrino transition magnetic moment and nonzero neutrino mixing we analyze the displacement of the allowed (

Neutrino spin-flavor conversions and νe emission from the sun with random magnetic field

\Delta m^2- \sin^22\theta

Electron antineutrinos from the sun with random magnetic fields

)-parameter region reconciled for the SuperKamiokande(SK) and radiochemical (GALLEX, SAGE, Homestake) experiments in dependence on the r.m.s. magnetic field value

Neutrino conversions in random magnetic fields and

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, or more precisely, on a value