Laboratory measurements of the opacity of solar plasmas

Accurate quantitative opacities relevant to the boundary between the convection and radiative zone of the Sun and other similar plasmas will be made using a novel EUV laser probing technique. To produce quantitative opacity measurements that can be used to improve the precision of the Rosseland mean opacity employed in the Standard Solar Model, we need to implement advances in experimental technique and increase the plasma density and temperature uniformity and range of measurement alongside a major modelling and simulation effort on plasma opacity. The positions of spectral lines and their oscillator strengths are tabulated by databases such as the Opacity Project. Our measurements will enable comparisons between theory and experiment to check the systematic absolute accuracy of the spectral line wavelengths (to within +/- 0.02 nm) and the accuracy of spectral line broadening models at high density (again to within +/- 0.02 nm). The measurement of laser ablation using EUV laser probing under different ablation regimes including with x-ray heating will be explored and the production of plasmas directly by focussed EUV irradiation will be investigated.