Ionization probabilities calculated using qprop (http://www.physik.uni-rostock.de/en/physik-forschung/research-groups/qtmps/qprop/) for the interaction of a laser beam with hydrogen atoms for intensities up to 1e16 W/cm2, frequencies between 0.2 and 2 au and durations between 100 and 20000 cycles.
These ionization probabilities have been used to explore a new method to produce proton beams by direct laser ionization as described in the paper "Laser stripping of hydrogen atoms by direct ionization" (E. Brunetti et. al, New Journal of Physics).