Twodimensional MHD model of the reconnection diffusion region
Erkaev N. V., Semenov V. S., Biernat H. K.
Nonlinear Processes in Geophysics. —
2002. — Vol. 9. — P. 131–138.
Full text of the article [pdf, 710 Kb, in english]
Magnetic reconnection is an important process
providing a fast conversion of magnetic energy into thermal
and kinetic plasma energy. In this concern, a key problem
is that of the resistive diffusion region where the reconnec-tion
process is initiated. In this paper, the diffusion region
is associated with a nonuniform conductivity localized to a
small region. The nonsteady resistive incompressible MHD equations are solved numerically for the case of symmetric
reconnection of antiparallel magnetic fields. A Petschek type
steady-state solution is obtained as a result of time relax-ation
of the reconnection layer structure from an arbitrary
initial stage. The structure of the diffusion region is studied
for various ratios of maximum and minimum values of the
plasma resistivity. The effective length of the diffusion re-gion
and the reconnection rate are determined as functions of the length scale and the maximum of the resistivity. For suf-ficiently
small length scale of the resistivity, the reconnection
rate is shown to be consistent with Petschek's formula. By increasing the resistivity length scale and decreasing the re-sistivity
maximum, the reconnection layer tends to be wider,
and correspondingly, the reconnection rate tends to be more
consistent with that of the Parker-Sweet regime.