SOFT-X-RAY BRILLIANCE OF FEMTOSECOND AND PICOSECOND LASER-PLASMAS

Soft x-ray spectra (10-70 Angstrom) from carbon and aluminium plasmas produced by high-intensity laser pulses have been studied as a functio n of laser pulse duration (130 fs-1.3 ps) and intensity (10(14)-5 x 10 (17) W cm(-2)) for two different laser wavelengths (248 and 800 nm). T he x-ray energy emitted from the plasma into specific lines and into t he continuum has been measured by means of an absolutely calibrated x- ray spectrograph and thus allows the water window x-ray yield from pla smas produced by long and short wavelength laser radiation to be compa red directly. Comparison was made between the dependence of the x-ray energy and width of the x-ray lines on the laser pulse duration, wavel ength and intensity. The experimental results have been related to hyd rocode simulations.