Intense-field multiphoton ionization of a two-electron atom

Abstract

Multiphoton ionization of helium at high laser intensities has been investigated by direct numerical integration of the full time-dependent two-electron Schrödinger equation on a Cray T3D. At field intensities above , two-photon ionization occurs in a few field periods, and double ionization and high harmonic generation are prominent. We present calculations of double ionization yields, investigate the sensitivity of double ionization to the electron - electron electrostatic repulsion, and present evidence of unexpected non-exponential behaviour in ionization decay rates.