X-ray polarization-dependent measurements of solid-density plasmas generated by fs laser pulses

We report on studies of plasmas, formed by the interaction of 80 fs, 1 J Ti:Sapphire laser pulses with solid matter. The laser intensity was 5 × 1019 W/cm2. The Kα1, 2 X-ray emission spectra at ≈4.5 keV were measured using a toroidally bent GaAs (400) crystal spectrometer with the spectral and spatial resolutions of 0.3 eV and 4 μm, respectively. A Si (220) polarizer was used for determining the polarization properties of the recorded emission. A strong polarization dependence of the Kα satellite emission was observed, which may indicate an anisotropy of the relativistic electron velocity distribution. Also, electrons with energies in the range of 500 keV–13 MeV were detected using an electron spectrometer.