Above threshold ionization with ultrahigh intensity laser light

The progress in technology of the ultrahigh power lasers gave physicists a new tool for exploring new extreme regimes of interaction between electro- magnetic field and matter, as well as resulting extreme states of matter. With the development of petawatt class lasers and implementation of techniques for better focusing (adaptive optics, such as deformable mirrors) intensities of ~ 10²³ W/cm² should become available in the near future. The electric field of a laser focused to the intensity of 10²¹ W/cm² can accelerate an electron from rest to ultra-relativistic energies of hundreds of MeV within a fraction of the laser period. What happens to electrons bound in atomic or ionic systems at these intensities is not quite clear and existing theories are largely qualitative. The goal of the work described in this thesis was to obtain some quantitative theoretical, as well as experimental results pertaining to ionization of rarefied gases at ultrahigh intensities. Some results of theoretical and computational work were published in PRL [1]. Several experimental runs were performed using Hercules laser of the Center for Ultrafast Optical Science (CUOS) in the University of Michigan. Hercules running at 10 TW level could in principle provide the focused intensity of about 4 x 10²⁰ W/cm² with the optics used. The experiment faced a great number of difficulties, so that no truly new results were obtained. The problems are being worked on