OBSERVATION OF AMPLIFIED SPONTANEOUS EMISSION IN THE SOFT-X-RAY REGION FROM A RECOMBINING LITHIUM-LIKE ALUMINUM PLASMA PUMPED BY MULTIPULSEIRRADIATION

An aluminum slab target was irradiated by 1.5 x 10(12) W/cm(2) glass-l aser light. The irradiating laser light consisted of 16 pulses, each w as 80 ps wide (FWHM), and the pulses were separated by 100 ps. Amplifi cation of soft-x-ray light in the lithiumlike aluminum recombining pla sma was observed, and gain-length products of 4.2 for the 15.4-nm line and 4.5 for the 10.5-nm line were obtained for a 3.0-cm-long target. The beam divergence was similar to 10 mrad for a 2.5 cm-long target. T he experimental result was compared with a hydrodynamics simulation co upled with a collisional-radiative model. (C) 1997 Optical Society of America.