In the framework of the CRYSTAL proposal for the pro-
duction and studies of ordered beams, a direct imaging di-
agnostics of longitudinal structures of ordered ions is now
under development. The fundamental elements of the di-
agnostics device are a thin foil, an accelerating grid, an
RF camera and an imaging detector. The thin carbon foil
is responsible for the direct production of time correlated
electrons upon the arrival of ordered ions. The accelerating
grid (10-15 kV) is used to enhance the time correlation of
the electrons against the angular spread of emission. The
accelerating grid is followed by the RF camera, working at
2.465 GHz, for the transverse deflection of the correlated
electrons. A detector with spatial resolution around 50 micron
is foreseen after a drift length of 30 cm. The time response
of the thin carbon foil was investigated with a Monte Carlo
method with particular emphasis to electrons with kinetic
energies smaller than few hundreds eV. According to the
adopted model, the time lags originated by the transport of
the primary electrons through the thin foil are limited at few
tens of femto-seconds
