Time-duration dependence from the simultaneous measurements of iron K- and L-shell radiation from laser produced plasmas

Abstract

High resolution X-ray spectra of plasmas produced by the interaction of Ti:Sa laser pulses (duration from 60 fs to 1 ps, and energy from 15 mJ to 128 mJ) with a solid Fe target are investigated experimentally and theoretically. Interestingly, both L-shell and K-shell Fe spectra were simultaneously measured while changing the time-duration of the laser experiments. In particular, the L-shell Fe radiation from F-, Ne-, and Na-like ions between ∼14–16.3 Å were observed from the first order reflection with a mica crystal. Simultaneously measured alongside the L-shell radiation was the Fe cold Kα lines (∼1.94 Å), from 8th order reflection. Two non-LTE Fe kinetic models have been developed to account for the L-shell radiation from the Fe ions and for the K-shell radiation from the low ionization stages emitting the Fe cold Kα lines. Preliminary analysis of the simultaneously measured Fe L- and K-shell radiations from changing the time-duration of the experiments shows varying relative line intensities from different ionization stages. Resulting plasma parameters as well as the opacity of the strongest resonance line, 3C, and their dependence on changing the time-duration will be discussed.