Interaction of a hydrogen atom with an intense pulse of vacuum ultraviolet radiation

摘要: The free electron laser (FEL) which is currently under construction at the DESY laboratory should deliver a photon beam in vacuum ultraviolet (VUV) range. Coherent radiation of FEL will soon allow for testing matter-electromagnetic field interaction very exotic conditions. In this paper we study ionization hydrogen atom by intense (about 10 16 Wc m 2 ) photons with energies 17 eV. We compare exact numerical results predictions perturbation theory showing limits its applicability and discussing requirements pulse parameters are necessary observation non-perturbative phenomena. rapid development powerful pulsed lasers operating optical domain has initiated great interest response atoms, molecules also large clusters to strong electromagnetic field. It now possible produce scale pulses electric significantly exceeding typical binding fields above-mentioned objects. At these intensities, matter highly nonlinear character, leads number unexpected Among them most celebrated examples are: above-threshold (ATI), multi-electron stabilization high-harmonic generation, Coulomb explosion (1). Description phenomena difficult because their character. Processes involving many electrons particularly complex therefore less understood. Currently facing another breakthrough technology. project TESLA test facility be completed around year 2000 (2). first stage amplifier, based on self-amplification spontaneous emission (SASE), operate up 390 MeV production from eV 30 intensities . duration expected equal few picoseconds. comprise train about 100 coherent characteristic coherence time order fs. Ionization atoms (Cl Xe) realistic range has, time, been studied recently Brewczyk