Precision X-ray spectroscopy of intense laser-plasma interactions

Polarisation sensitive emission spectroscopy measurements are reported for a petawatt laser-solid target interaction at intensities up to 5 x 10(20) Wcm(-2). These measurements were single-shot and used pairs of highly-orientated graphite spectrometers to resolve the sulphur Ly-alpha doublet. The sulphur Ly-alpha(1) component shows a large positive polarisation indicative of a low energy electron beam in the plasma, the Ly-alpha(2) component acts as a cross-spectrometer calibration. The measurements show a significant anisotropic or beam-like component to a cold return current. (C) 2011 Elsevier B.V. All rights reserved.