  Many in-situ spacecraft observations have demonstrated that magnetic
reconnection in the Earth's magnetotail is largely controlled by the
pre-reconnection current sheet configuration. One of the most important thin
current sheet characteristics is the preponderance of electron currents driven
by strong polarized electric fields, which are commonly observed in the Earth's
magnetotail well before the reconnection. We use particle-in-cell simulations
to investigate magnetic reconnection in the 2D magnetotail current sheet with a
finite magnetic field component normal to the current sheet and with the
current sheet polarization. Under the same external driving conditions,
reconnection in a polarized current sheet is shown to occur at a lower rate
than in a nonpolarized current sheet. The reconnection rate in a polarized
current sheet decreases linearly as the electron current's contribution to the
cross-tail current increases. In simulations with lower background temperature
the reconnection electric field is higher. We demonstrate that after
reconnection in such a polarized current sheet, the outflow energy flux is
mostly in the form of ion enthalpy flux, followed by electron enthalpy flux,
Poynting flux, ion kinetic energy flux and electron kinetic energy flux. These
findings are consistent with spacecraft observations. Because current sheet
polarization is not uniform along the magnetotail, our results suggest that it
may slow down reconnection in the most polarized near-Earth magnetotail and
thereby move the location of reconnection onset downtail.
