X-Ray Laser Thomson Scattering at 21 nm of Laser-Heated High-Density Foil Plasmas

Results of our preliminary studies for a demonstration of soft X-ray laser Thomson scattering in laser-produced dense plasma are presented. The investigated plasmas are produced by single-side heated foil targets using a 300-ps pulse of 438-nm wavelength at irradiances between 10(13) and 10(14) Wcm(-2). The Ne-like zinc X-ray laser, delivering similar to 1 mJ of focused energy at 21.2 nm, is injected to the plasma as the Thomson probe. The X-ray laser pulse is timed to arrive to the plasma 0.5 or 1 ns after the peak of the optical pulse, encountering electron densities in the range of 10(20)-10(22) cm(-3). The spectrum near 21 nm, emitted at similar to 30 degrees with respect to the incident X-ray laser, is analyzed by a flat-field spectrometer viewing through the back of the target. The results show that the choice of appropriate target material and thickness are essential to the success of this experiment. From the spectroscopic measurements using Al and polypropylene (CA) foils, the latter appears as a suitable candidate for Thomson scattering experiments near 21 nm. A weak spectral feature near 21.2 nm potentially indicating Thomson scattering was observed using a 1.2 mu m polypropylene foil. Further data analysis is required to support this conclusion.