  The non-equilibrium transportation of two-dimensional electrons through a
narrow channel is investigated under the influence of the Rashba interaction.
By introducing suitable lifetime in the Green's function, the average spin
values can be calculated from the ballistic regime to the diffusive regime. It
is shown that the spin accumulation is a combined effect of the spin current
and disorders. In the diffusive regime, disorders offer a mechanism to stop the
spin current and generate the spin accumulation. In the ballistic regime, spins
are more spread out and do not have definite signs. Further consideration
indicates that the inclusion of ferromagnetic spin-spin interaction increases
the spin accumulation near the edge.
