  We perform a number of numerical simulations of the solar corona with the aim
to understand how it responds to different conditions in the photosphere. By
changing parameters which govern the motion of the plasma at the photosphere we
study the behavior of the corona, in particular, the effects on the current
density generated. An MHD code is used to run simulations, using a 20x20x20
Mm^3 box with time spans ranging from one hundred to several hundreds of
minutes. All the experiments show a fast initial increase of the current
density, followed by a stabilization around an asymptotic value which depends
on the photospheric conditions. These asymptotic average current densities as
well as the turn-over points are discussed.
