SOFT-X-RAY EMISSIONS FROM LINE-FOCUS SHORT-PULSE-DRIVEN RECOMBINING LASER-PRODUCED PLASMAS

The 0.268 mu m KrF Raman pumped SPRITE laser facility at the Rutherford Appleton Laboratory has been used to produce recombining line focus plasmas. SPRITE delivers up to 6 J in 12 psec in a single beam. Experimental studies of the sub-keV x-rays emitted from these short-pulse-driven recombining plasmas have been undertaken. Carbon fibre targets of up to 6.0 mm length have been used to produce plasmas which emitted soft x-rays in the range 50 - 124 eV. Time-integrated, space-resolved and time-resolved, space-integrated measurements of these emissions have been made with grazing incidence flat field spectrometers set at different angles of observation relative to the surface of the carbon fibre targets. The spatial and temporal intensity distributions of the carbon hydrogen-like Balmer-alpha and Balmer-beta transitions, 182.17 Angstrom and 134.95 Angstrom respectively were investigated as a function of target length. Although modelling predicts peak gain-length products for the current conditions of as high as 10 we have not been able to unambiguously observe amplification on the Balmer-alpha line at 182.17 Angstrom with the data recorded.