Dynamics of debye-scale nonstationary plasma structures in the region of auroral field-aligned currents

We consider the formation of small-scale nonstationary plasma structures in the region of relatively strong field-aligned electric currents. The formation of these structures has been shown to be associated with the density instability developed when the current velocity exceeds a critical value. The conditions for the development of this instability can be most favorable in the region of low-density plasma. Numerical calculations have been performed for the initial nonlinear stage of the structure development. The main parameters of the structure, i.e., the times of its formation and destruction, spatial scales, and electric field, have been estimated. The features of the structures are consistent with the existing data from space experiments in the region of auroral field-aligned currents of the Earth.