C-VI LYMAN LINE-PROFILES FROM 10-PS KRF-LASER-PRODUCED PLASMAS

Plasmas with densities less than or similar to 10(22) cm(-3) and electron temperatures T-e less than or similar to 200 eV were produced near solid graphite targets that were laser irradiated at approximately 10(15) W/cm(2), with a similar to 10(11) W/cm(2) prepulse from amplified spontaneous emission. Photographic spectra taken nearly side-on within 0.1 mm from the target surface show strong H-like lines corresponding to n = 2, 3, and 4 to n = 1 transitions and weaker He-like lines with full width at half maximum widths less than or similar to 4 eV. The Lyman-alpha line is optically thick. A five-layer model with high-electron-density and electron-temperature core layers and less dense and cooler outer layers was used for simulation. Central layers with high T-e contribute most of the emission while outside cooler layers cause an absorption dip in the central part of the Lyman-alpha line. Asymmetrical self-reversal is interpreted by radial expansion. A plasma-induced line shift was evident in some of the experimental line profiles, especially for the asymmetrical and strongly shifted Lyman-gamma Line of C VI ions. Time-dependent rate equations were solved for checking the assumed local-thermodynamic-equilibrium condition for plasmas with adiabatic expansion cooling.