Physical parameter dependence of the X-ray generation in intense laser-cluster interaction

Studies on laser-cluster interaction performed on the LUCA facility (French acronym for Ultra Short Tunable Laser, CEA Saclay) allow to observe the production of hard X-rays in the 1-5 keV range when rare gas clusters of nanometer sizes are heated by strong optical fields (F > 109 V/cm). First complete quantitative measurements of absolute photon emission yields, as well as of charge state distributions of ionic species with inner shell vacancies have been performed as a function of several physical parameters governing the interaction. Our measurements give rise to fundamental results like an optimum heating time and an intensity threshold in the X-ray production. These data provide direct insight into the interaction dynamics and into the heating processes involved.