  We investigate the process of Abelian pair production in the presence of
strong inhomogeneous and time-dependent external electric fields. The spatial
dependence of the external field is motivated by a non-Abelian color flux tube
in heavy-ion collisions. We show that the inhomogeneity significantly increase
the particle yield compared to that in the commonly used models with a constant
and homogeneous field. Moreover our results indicate that in contrast to the
latter, most of the particles are produced at the interface of the field
profile in accordance with Heisenberg's prediction.
