SPACE-RESOLVED INVESTIGATION OF LASING ON THE 2 J=0-1, 3P-3S TRANSITIONS AT 20.5 AND 25.5 NM IN NEON-LIKE IRON

We report a spatially resolved investigation of lasing on the 3p(1)S(0 )-3s(3)P(1) and 3p(1)S(0)-3s(1)P(1) transitions at 20.5 and 25.5 nm in neon-like iron. Using the Asterix IV iodine laser slab targets were i rradiated at an intensity of 2.0 x 10(13) W cm(-2) with a prepulse 5.2 ns before the main pulse. With a 1.5% prepulse, the gain of the two l asers was measured to be 2.3 and 4.1 cm(-1) at their spatial maxima. T he lasing on the 20.5 nm line was measured to occur slightly farther f rom the target surface than on the 25.5 nm line. The dependence of the lasing position on the prepulse energy was also investigated. Increas ing the prepulse to 15% shifts the lasing position by 100 mu m farther away from the target.