Abstract
Abstract
Strong field atomic frustrated double ionization (FDI) represents a novel approach for ultrafast preparation and control of highly excited ions. A comprehensive understanding of its mechanism is of fundamental significance. However, current interpretations are restricted to the dipole approximation. Here, the nondipole effect in FDI of Ar is investigated using a classical ensemble model, in which the magnetic component of the laser field is fully accounted for. We show that the magnetic field induces positive momentum of photoelectrons along the laser propagation direction, which depends on the laser intensity. By tracing the electron trajectories, it is found that the linear momentum transfer to photoelectrons is considerably enhanced by recollision. The ionization time distribution of electrons and corresponding momenta play important roles in the momentum transfer. The subcycle evolution of magnetic fields is related to the variation of momentum transfer for positive and negative momentum of photoelectrons along the laser polarization. This work provides an intuitive insight into the nondipole effect in FDI and offers a scheme for probing ultrafast magnetic fields and manipulating the linear momentum transfer.