Aluminium He-β High-Resolution Spectroscopy and the Observation of High Field Processes

Helium-like aluminium (Z=13) plasmas created using long (nanosecond) and short (picosecond) duration laser pulses at intensities between 5 x 1013 and 5 x 1016 W/cm2 were studied using a combination of optical and X-ray spectroscopy methods and computational modeling tools. The experiments were designed to ensure that the K-shell emission spectra from the aluminium plasmas was measured in detail and that the spectra could be reproduced through a combination of hydrodynamic, atomic kinetic, and radiation transport models. Detailed spectral line shapes, with high spectral and spatial resolution, were recorded in an attempt to positively observed single frequency electric fields effects due to the application of a strong laser field, and due to strong laser-driven plasma waves. Spectral line shape modification due to laser-driven plasma waves was observed, yet there is no evidence for direct laser field effects. Experimental procedures and the computational work are outlined, the observation of modulated intensity profiles on the He-β transition and the interpretation based on intra-Stark spectroscopy discussed