  We investigate the ionization and the opacity of warm, dense helium under
conditions found in the atmospheres of cool white dwarf stars. Our particular
interest is in densities up to $\rm 3 g/cm^{3}$ and temperatures from 1000K to
10000K. For these physical conditions various approaches for modeling the
ionization equilibrium predict ionization fractions that differ by orders of
magnitudes. Furthermore, estimates of the density at which helium
pressure-ionizes vary from $\rm 0.3$ to $\rm 14 g/cm^{3}$. In this context, the
value of the electron-atom inverse bremsstrahlung absorption is highly
uncertain. We present new results obtained from a non-ideal chemical model for
the ionization equilibrium, from Quantum Molecular Dynamics (QMD) simulations,
and from the analysis of experimental data to better understand the ionization
fraction in fluid helium in the weak ionization limit.
