SPATIAL POSITION OF PREPULSE INDUCED J=0-]1, 3P-3S LASING IN LOW-Z NEON-LIKE IONS

We report a spatially resolved investigation of lasing on the 3p 1S0-3s 1P1 transition in neonlike ions ranging from titanium (Z=22) to germanium (Z=32). Slab targets were irradiated by the Asterix IV iodine laser at an intensity of about 2.0×1013 W/cm-2 with a prepulse 5.23 ns before the main pulse. The lasing position was measured as a function of the prepulse energy and the atomic number. It was found that with higher Z, the lasing occurs closer to the target surface and a larger prepulse brings the lasing farther away from the target. A 15% prepulse was found to be favorable for low-Z elements (such as titanium), while a 1.5% prepulse was found to be favorable for elements with Z higher than 26. A simple model taking into account the self-similar expansion of the plasma produced by the prepulse was found to agree qualitatively with the experimental results. © 1995 The American Physical Society.