Application of a picosecond laser plasma continuum light source to a dual-laser plasma photoabsorption experiment

The characteristics of an extreme-ultraviolet (XUV) continuum light source and its application to a dual-laser plasma (DLP) photoabsorption experiment are described. The continuum emitting plasma was formed by focusing a 7 ps , 248 nm, 15 mJ laser pulse onto a number of selected targets known to be g ood XUV continuum emitters (Sm, W, Au and Pb), while the second absorbing p lasma was produced by a 15 ns, 1064 nm, 300 mi pulse. The duration of the c ontinuum emission for these plasmas has a mean value of similar to 150 ps, but depends on both the target material and the picosecond laser pulse ener gy. Using this picosecond DLP set-up we have been able to measure the photo absorption spectrum of an actinide ion (thorium) for the first time.