Time resolved X-ray spectroscopy of thin foil heated by 100 fs, 10^18 W/cm^2 laser pulse
Abstract
We have performed experiments on thin foils under well controlled conditions at the Lawrence Livermore National Laboratory Ultra-Short Pulse Laser (USP) to study the temperature and density characteristics of laser heated solids. To minimize resonance absorption, the experiment was conducted with frequency doubled, S-polarized light with a peak intensity of 10^19 W/cm^2 ( I λ ^2 = 2 × 10^18 W μ m^2/cm^2 ). The X-ray emission was recorded using a new two crystal von Hamos spectrometer coupled to the LLNL 500 fs resolution streak camera. We recorded the helium-like 1s^2-1snp transitons He_α, He_β and He_γ of aluminum as function of time. Very thin ( 250\: Å\: Åaluminum foil targets were used to decrease the effect of temperature gradients and minimize optical depth effects. The time resolved spectra shows an unexpected intense 'continuum' between He_β and He_γ due to unresolved satellite line emission. Additionally, the He_α line has an extended blue wing which has a short lifetime (≈ 4 ps). The results will be presented and discussed.
- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- November 1999
- Bibcode:
- 1999APS..DPP.JP174S