A class of approximate solutions of the Schrödinger equation for an atom in a time-dependent electric field that scales with the applied field F as FF(t)dt is derived and their bounds of validity are carefully examined. The class covers a wide region of applicable electric fields and its time constants. An extensive comparison of these solutions with the results of numerical calculations on a truncated basis of up to 465 hydrogenic states shows surprising agreement. One of these solutions is found to be very effective in field dressing of high Rydberg states. The resulting field dressing is proposed for the description of the plasma field effects on atomic reaction rates, but its range of applicability can be extended to the other atomic problems that involve time-dependent electric fields.

• Received 19 March 1993

DOI:https://doi.org/10.1103/PhysRevA.48.4515