THE INFLUENCE OF PREPULSE LEVEL ON THE 3P-3S XUV LASER OUTPUT FROM NE-LIKE IONS OF ZN, CU AND NI

We have studied the effect of prepulses in enhancing the efficiency of generating ASE beams in soft X-ray laser plasma amplifiers based on p umping Ne-like ions, Slab targets were irradiated with a weak prepulse followed by a main plasma heating pulse of nanosecond duration, Time- integrated; time and spectrally resolved and time and angularly resolv ed lasing emissions on the 3p-3s (J=0-1) XUV lasing lines of Ne-like N i, Cu and Zn at wavelengths 232 Angstrom 221 Angstrom and 212 Angstrom respectively have been monitored. Measurements were made for pre-puls e/main-pulse intensity ratios from 10(-5)-10(-1) and for pump delay ti mes of 2 ns and 4.5 ns. Zinc is shown to exhibit a peak in output inte nsity at similar to 2x10(-3) pre-pulse fraction for a 4.5 ns pump dela y, with a main pulse pump intensity of similar to 1.3x10(13) W cm(-2) on a 20 mm target. The Zn lasing emission had a duration of similar to 240 ps and this was insensitive to prepulse fraction. The J=0-1 XUV l aser output for nickel and copper increased monotonically with prepuls e fraction, with copper targets showing least sensitivity to either pr epulse level or prepulse to main pulse delay. Under the conditions of the study, the pre-pulse level was observed to haveno significant infl uence on the output intensity of the 3p-3s (J=2-1) lines of any of the elements investigated.