  Reconnection physics at micro-scales is investigated in an electron
magnetohydrodynamics frame. A new process of collapse of the neutral current
sheet is demonstrated by means of analytical and numerical solutions. It shows
how at scales smaller than ion inertia length a compression of the sheet
triggers an explosive evolution of current perturbation. Collapse results in
the formation of a intense sub-sheet and then an X-point structure embedded
into the equilibrium sheet. Hall currents associated with this structure
support high reconnection rates. Nonlinear static solution at scales of the
electron skin reveals that electron inertia and small viscosity provide an
efficient mechanism of field lines breaking. The reconnection rate does not
depend on the actual value of viscosity, while the maximum current is found to
be restricted even for space plasmas with extremely rare collisions. The
results obtained are verified by a two-fluid large-scale numerical simulation.

Plasma Physics