Laser-Matter Interaction with Intense Short Laser Pulses

Laser-matter interaction in rare gases (He, Ne, Ar and Xe) has been investigated using a 1 ps Nd-glass laser pulse at 1053 nm with intensities between 10$\text{}^{13}$ to 10$\text{}^{18}$ W/cm$\text{}^{2}$. Three aspects of the interaction have been studied: the creation of multiply charged ions, the energy of the ejected electron and the propagation in an underdense plasma. At the maximum laser intensity, all electrons of the outer shell are removed, except in Ne for which charge states up to 7+ are observed. Comparison of experimental data with Ammosov et al. tunneling model shows a very good agreement, indicating that ionization with a 1 ps pulse in the near infrared light mainly occurs in tunneling regime. Electrons created in a low-density medium with energies up to 5 keV have been detected. These energies are far above the energy acquired during the ionization process, indicating that at high laser intensities electron energy is governed by ponderomotive force. Finally, the study of the propagation of an intense laser pulse in an underdense plasma shows that it is not possible to obtain simultaneously high laser intensity (10$\text{}^{17}$-10$\text{}^{18}$ W/cm$\text{}^{2}$) and high electron density (10$\text{}^{19}$-10$\text{}^{20}$ cm$\text{}^{-3}$). Best conditions for solving this problem will be discussed.