Small-scale reconnection due to lower-hybrid drift instability in current sheets with sheared fields

Abstract

The consequences of small-scale lower-hybrid drift (LHD) instability for reconnection through thin current sheets are investigated in dependence on guide magnetic field By0 by three-dimensional Vlasov-code simulations. The LHD waves are amplified by inverse resonant Landau damping on ion flow. In current sheets separating antiparallel magnetic fields the LHD waves can trigger global current-aligned eigenmodes, which directly couple to the tearing-mode instability. Depending on the initial conditions either small-scale, three-dimensional, or small-scale two-dimensional reconnection prevails. In the presence of a moderate guide magnetic field up to By0=B0, where B0 is the asymptotic Bx field, the unstable LHD waves propagate obliquely to the current direction, at different angles from the opposite sides of the current sheet. The resulting patchy three-dimensional small-scale reconnection grows significantly slower, compared to reconnection in antiparallel fields.