Session 6E - High Intensity Laser Plasma Interactions.
ORAL session, Wednesday afternoon, November 13
Majestic Ballroom, Adam's Mark
In the present set of experiments, we examine the competition between cooling due to expansion versus thermal conduction and the effect of the target thickness on line shape. The experiment is done using thin aluminum foils of successive thickness ranging from 250 Å\, to 1250 Å\,. The foils were heated with a 400 nm,
150 fs (FWHM) ultra short pulse laser. The laser energy was approximately 200 mJ and was focused to a spot size of 3 \mu\,m, resulting in a peak intensity of \,1.9\,\times\,10^19\,W/cm^2\,. The prepulse to main pulse contrast was determined to be better than \,10^-7\,. The \,1s^2-1s2p\,, \,1s^2-1s3p\, transitions in He-like aluminum and the \,1s-2p\, transitions in H-like aluminum were temporally resolved using a 900 fs x-ray streak camera. These spectral lines are used to determine the effects of target thickness, and hence thermal conduction, on the rate of cooling in the plasma. A simple model is used to interpret the experiment. We present the data and findings from this study. \hrule width4cm \vskip .1in + Work performed under the auspices of the U.S. Dept. of Energy by Lawrence Livermore National Laboratory under contract W-7405-ENG-48.