  The instantaneous charge state of uranium ions traveling through a fully
ionized hydrogen plasma has been theoretically studied and compared with one of
the first energy loss experiments in plasmas, carried out at GSI-Darmstadt by
Hoffmann \textit{et al.} in the 90's. For this purpose, two different methods
to estimate the instantaneous charge state of the projectile have been
employed: (1) rate equations using ionization and recombination cross sections,
and (2) equilibrium charge state formulas for plasmas. Also, the equilibrium
charge state has been obtained using these ionization and recombination cross
sections, and compared with the former equilibrium formulas. The equilibrium
charge state of projectiles in plasmas is not always reached, it depends mainly
on the projectile velocity and the plasma density. Therefore, a non-equilibrium
or an instantaneous description of the projectile charge is necessary. The
charge state of projectile ions cannot be measured, except after exiting the
target, and experimental data remain very scarce. Thus, the validity of our
charge state model is checked by comparing the theoretical predictions with an
energy loss experiment, as the energy loss has a generally quadratic dependence
on the projectile charge state. The dielectric formalism has been used to
calculate the plasma stopping power including the Brandt-Kitagawa (BK) model to
describe the charge distribution of the projectile. In this charge
distribution, the instantaneous number of bound electrons instead of the
equilibrium number has been taken into account. Comparing our theoretical
predictions with experiments, it is shown the necessity of including the
instantaneous charge state and the BK charge distribution for a correct energy
loss estimation. The results also show that the initial charge state has a
strong influence in order to estimate the energy loss of the uranium ions.
