CHARACTERISTICS OF PLASMA-HEATING BY SHOR T-WAVELENGTH EXCIMER-LASER RADIATION

Various x-ray spectroscopic methods were used to investigate a plasma generated by the interaction of short-wavelength excimer laser radiati on pulses (12 ns, 0.308 mu m, 4.10(-12) W/cm(2)) with flat targets. A comparison of the profiles and intensities of a number of observed spe ctral lines of the H-like, He-like, and Li-like sodium, magnesium, and aluminium ions with the results of the reported calculations made it possible to determine the spatial distributions of the laser plasma pa rameters Up to distances of similar to 0.4 mm from the target surface. These parameters were compared with the predictions of a simple theor etical model of the absorption of short-wavelength radiation in a plas ma. This showed that the absorption of such radiation (with the intens ities used in this investigation) involved inverse bremsstrahlung in r egions with an electron density much lower than the critical value.