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

摘要

The consequences of small-scale lower-hybrid drift (LHD) instability for reconnection through thin current sheets are investigated in dependence on guide magnetic field B-y0 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 B-y0 = B-0, where B-0 is the asymptotic B-x 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. (C) 2005 American Institute of Physics.