Classical study of atomic bound state dynamics in circularly polarized ultrastrong fields

We investigate hydrogen-like atoms in ultrastrong fields up to 1000 au (3 × 1022 W cm−2). We find the influence of the magnetic component (Blaser) of the external ultrastrong field introduces perturbations for the bound states of the atom. For intensities up to 1 × 1019 W cm−2 the changes in the trajectory energies and Poincaré plots are on the order of a few per cent. While small, the changes from Blaser with circular polarized (CP) light can result in a several-fold decrease in the ionization probability at the highest intensities for the bound states, where ionization approaches 50%. For these highest intensities, we find the Lorentz force from Blaser exerts a force on the bound electron perpendicular to the rotating plane of the CP light. Since these trajectories are then aligned away from the minimum in the potential barrier it is stabilized against tunnelling ionization. The results provide a classical understanding for ionization in ultrastrong fields and indicate that relativistic effects in ultrastrong field ionization may most easily be seen with CP fields.