X-Ray Laser Progress and Applications Experiments at LULI

The neon-like zinc X-UV laser implemented at the Laboratoire d’Utilisation des Lasers Intenses (LULI, Palaiseau, France) emits its strongest lasing line at 21.2 nm (3p_j=0 - 3s _j=1 transition). The driving laser provides 0.45 KJ-600 ps pulses at 1,06μm. The current configuration of the X-UV laser uses a bent multilayer mirror making up a double-pass half-cavity. The mechanical system affords several tens of shot without manually adjusting or renewing the cavity mirror nor the slab target. In order to ensure reliable laser operation it has been necessary to improve the control of the pumping laser beam profile, of the prepulse contrast and to investigate the effect of target curvature. In its present configuration the laser yields up to 10¹⁴ photons per 80-ps pulse in 3.10-5 mrad². The total energy emitted during the pulse amounts to ∼ 1 mJ. The pulse-averaged power is of 12 - 15 MW. The transverse coherence length is about 50 μm at 50 cm from the amplifying plasma end. A large effort is devoted to making this laser an efficient tool for scientific and technical research. Up to 30 shots per day can be used in application experiments. The application program involves plasma diagnostics, interferometry and photoluminescence experiments. The laser-excited UV-luminescence of Csl crystal shows a strongly non-linear luminescence-yield behaviour at high excitation flux.