  Kinetic Boltzmann equations are used to model the ionization and expansion
dynamics of xenon clusters irradiated with short intense VUV pulses. This
unified model includes predominant interactions that contribute to the cluster
dynamics induced by this radiation. The dependence of the evolution dynamics on
cluster size, $N_{atoms}=20-90000$, and pulse fluence, $F=0.05-1.5$ J/cm$^2$,
corresponding to intensities in the range, $10^{12}-10^{14}$ W/cm$^2$ and
irradiation times, $\leq 50$ fs, is investigated. The predictions obtained with
our model are found to be in good agreement with the experimental data. We find
that during the exposure the cluster forms a shell structure consisting of a
positively charged outer shell and a core of net charge equal to zero. The
width of these shells depends on the cluster size. The charged outer shell is
large within small clusters ($N_{atoms}=20,70$), and its Coulomb explosion
drives the expansion of these clusters. Within the large clusters
($N_{atoms}=2500,90000$) the neutral core is large, and after the Coulomb
explosion of the outer shell it expands hydrodynamically. Highly charged ions
within the core recombine efficiently with electrons. As a result, we observe a
large fraction of neutral atoms created within the core, its magnitude
depending on the cluster size.
