X-ray line polarization spectroscopy to study hot electron transport in ultra-short laser produced plasma

Observation is reported of the polarization of the helium-like Cl-Heα line (1s2 1S0-1s2p 1P1), at 2.79 keV emitted from a triple-layer target irradiated with a 130 fs laser pulse. The polarization degree is determined as a function of overcoat thickness of the target. It is found that the emission from a layer closer to the target surface is polarized parallel to the surface direction whereas emission from a deeper region in perpendicular to the surface. The experimental result is analyzed using a two-dimensional (2D) Maxwellian distribution function for hot electrons. Beam-like distribution was found in the depth of plasma.