Long, Zi Jian2008-01-242008-01-242008-01-242008http://hdl.handle.net/10012/3530In order to understand how does the intense laser interact with matter we first of all study the ionization process. In this highly nonlinear region the conventional perturbation theory will fail to predict the experimental results. Alternative theories have been proposed in the past few decades. The fundamental difficulty in these new approaches is when laser field becomes so intense such that it is comparable to the Coulomb field at where the ground state electron mainly concentrate, we have to treat the laser field and the Coulomb field on an equal footing. The analytical solution that can describe the propagation of electron in both the laser field and the Coulomb field has not been found; therefore, in these new theories the ionization process is either divided temporarily into laser period and Coulomb period or spatially into laser field domain and Coulomb field domain. The propagation of electron in the full Hamiltonian is avoided.enIntenseLaserMaster ThesisPhysics