  We discuss double ionization of atoms in strong laser pulses using a reduced
dimensionality model. Following the insights obtained from an analysis of the
classical mechanics of the process, we confine each electron to move along the
lines that point towards the two-particle Stark saddle in the presence of a
field. The resulting effective two dimensional model is similar to the aligned
electron model, but it enables correlated escape of electrons with equal
momenta, as observed experimentally. The time-dependent solution of the
Schr\"odinger equation allows us to discuss in detail the time dynamics of the
ionization process, the formation of electronic wave packets and the
development of the momentum distribution of the outgoing electrons. In
particular, we are able to identify the rescattering process, simultaneous
direct double ionization during the same field cycle, as well as other double
ionization processes. We also use the model to study the phase dependence of
the ionization process.
