The Effect of Realistic Focal Conditions on Strong-Field Ionization

Jan Chaloupka
Department of Physics, College of William and Mary

ABSTRACT: Atoms in an intense laser field can become doubly ionized through a direct process known as rescattering, where a single electron is liberated through tunnel ionization and is driven back to the ion core by the laser field, leading to impact ionization and release of a second electron. Not surprisingly, the trajectory of the first liberated electron in the laser field has a strong influence on the probability of release of a second electron. Using completely classical 3-D simulations, we have studied the effects of realistic focal conditions on the single and double ionization yields from a model two-electron atom. In particular, variations in the longitudinal electric field throughout the focal volume can lead to interesting spatially dependent effects, due to an effective elliptical polarization even for a linearly polarized driving field. It is found that under conditions of tight focusing, the effective focal volume for nonsequential double ionization is significantly reduced. We will present our latest results from the simulation and discuss the likelihood of observing this effect experimentally.