PREPULSE DEPENDENCE OF J=0-1 LASING AT 32.6-NM IN NEON-LIKE TITANIUM

The dependence of the intensity of the 3p-3s, J = 0-1 lasing line at 3 2.6 nm in neon-like titanium on the prepulse level has been investigat ed experimentally. Titanium slabs were irradiated with 1.315 mu m/450 ps pulses from the Asterix IV iodine laser using a defined prepulse of 5.2 ns before the main pulse. It is found that for pump energies clos e to the minimum energy for which lasing is observed, a prepulse level of order 0.5% gives the highest XUV laser intensity, whereas a higher prepulse level, of order 10% and more, is required for optimum XUV la sing far above the threshold. For a 2.7 cm long titanium target lasing was observed down to a pump irradiance of 2.5 TW/cm(2) (50 J/450 ps) for the 0.5% prepulse.