Sequential pumping in Ne-like iron. Multiple irradiation of X-ray lasers

We study a X-ray laser (XRL) pumped by two 140 ps pulses from an IR laser b eam. With the aim to regenerate the plasma gain with the second pulse, and then realise a double pass, we separate the two pulses by 800 ps. First exp erimental results obtained at LULI with Ne-like iron were very encouraging. In single pass mode, two saturated X-ray laser emissions have been observe d with reproducible way. The gain values were respectively 15 cm(-1) and 12 cm(-1). This result qualitatively agrees with EHYBRID and Maxwell-Bloch mo delling. We present the first far field pattern obtained in Ne-like iron an d we deduce the two different positions of each XRL beam by subtracting ima ges.