Electron-positron pair creation by powerful laser-ion impact

In view of recently achieved extreme laser powers for which the ponderomotive energy U-p > 2mc(2), it has become of interest to reconsider fundamental processes of quantum electrodynamics in such powerful laser fields. In the present work, we evaluate the rates of producing electron-positron pairs by the impact of laser pulses of extreme power on highly charged ions at rest. Contrary to previous investigations, we shall consider a linearly polarized laser pulse, since at extreme laser powers the contribution of the A(2) part of the electromagnetic interaction becomes significant. As long as the duration of the laser pulses considered is in the femtosecond domain, the description of the laser beam by a powerful, monochromatic electromagnetic plane wave will still be justified, which simplifies considerably the calculations required.