Time-resolved X-ray spectroscopy of ultrashort plasmas

Summary form only given. Results obtained at INRS by using the C850X streak camera are discussed. The experiments were carried out using the INRS Table Top Terawatt 500-fs laser (1.053 /spl mu/m) at an intensity of 10/sup 16/ to 10/sup 17/ W/cm/sup 2/. Time-resolved spectra have been obtained for non-beam irradiation at 1 /spl mu/m and 0.53 /spl mu/m. The cold K/spl alpha/ emission is time-resolved, giving access to the time history of the hot electron generation processes. Time-resolved keV spectra have also been obtained with two colinear 0.53 /spl mu/m pulses incident on Al targets and separated by an adjustable delay (0-100 ps). In this experiment, very clean pulses (10/sup 10/:1 intensity contrast ratio) have been used. The first pulse creates a preplasma and the time delay between the two pulses makes it possible to adjust the density of the target at which the second pulse produces the X-ray emission. Control of the brightness and of the emission duration of the ultrafast X-ray source is thus achieved.