IMPROVED PHEBUS LASER PERFORMANCES REQUIRED FOR PRECISION LASER-TARGET EXPERIMENTS

The Precision Phebus program, started in 1993, emphasizes a series of laser and target experiment objectives on the two-beam Phebus Nd-phosp hate glass laser. Recently, three major objectives that are also very important issues for megajoule-class lasers have been met: First, the balance of the incident beam-to-beam 3 omega power is shown to be in t he range from 5 to 12% for 3-ns, 3 omega-shaped pulses of reproducible high-energy shots; second, the smoothing uniformity of the laser ener gy deposited on the target, that is, the contrast of the spatial beam modulations, can be kept lower than 5%; and, finally, the tight contro l of the beam targeting leads to a pointing precision of less than 10 mu rd on the target at the target chamber center (TCC) and of 80 mu rd on X-ray sources located up to 3 cm from the TCC to improve the space - and time-resolved X-ray shadowgraphy techniques performed for target physics experiments such as implosion and hydrodynamical instability studies.