We study the ionization of atoms in weak, strong, and ultrastrong laser fields and especially the possibility to approximate the sinusoidal electric field of the light by alternating δ kicks of appropriate strength. The dynamics of a one-dimensional model atom is considered as well as the real three-dimensional hydrogen atom. We found that the qualitative behavior of the ionization probability and the photoelectron spectrum is not changed by the above-mentioned approximation. However, the effect of the so-called stabilization in ultrastrong fields (fields far beyond the perturbation theory) is stronger with the kick approximation than for a realistic field. This can be understood within the framework of the Kramers-Henneberger picture.

• Received 25 June 1993

DOI:https://doi.org/10.1103/PhysRevA.49.1171