  A significant step has been made towards understanding the physics of the
transient surface current triggered by ejected electrons during the interaction
of a short intense laser pulse with a high-conductivity target. Unlike the
commonly discussed hypothesis of neutralization current generation as a result
of the fast loss of hot electrons to the vacuum, the proposed mechanism is
associated with excitation of the fast current by electric polarization due to
transition radiation triggered by ejected electrons. We present a corresponding
theoretical model and compare it with two simulation models using the FDTD
(finite-difference time-domain) and PIC (particle-in-cell) methods. Distinctive
features of the proposed theory are clearly manifested in both of these models.
