Laboratory measurements of the opacity of solar plasmas
Lead Research Organisation:
University of York
Department Name: Physics
Abstract
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.
Organisations
Publications

Gartside L
(2011)
Extreme ultraviolet interferometry of laser plasma material between the critical and ablation surfaces
in High Energy Density Physics

Gartside LM
(2010)
Extreme ultraviolet interferometry of warm dense matter in laser plasmas.
in Optics letters

Tallents G
(2009)
Measurements of opacity and temperature of warm dense matter heated by focused soft X-ray laser irradiation
in High Energy Density Physics

Wagenaars E
(2011)
A method to probe Rosseland and Planck mean opacities with high-order harmonics
in High Energy Density Physics

Whittaker D
(2009)
Iron opacity predictions under solar interior conditions Iron opacity predictions
in Monthly Notices of the Royal Astronomical Society
Description | The use of extreme ultra-violet (EUV) lasers for the probing of the opacity of high temperature, high density plasma was demonstrated. Simulations of opacity were undertaken using tabulated data and compared to measured EUV transmission. |
Exploitation Route | The plasma opacity in the region between the radiative and convection zones of the Sun is still uncertain with recent measurements by others showing, for example, factor of two discrepencies between soft x-ray transmission measurements of opacity and atomic physics simulations of iron opacity. Our results suggested that tabulated iron plasma opacities were approximately correct. The work led to a study investigating the use of EUV lasers to heat high density plasma, rather than simply acting as a probe. |
Sectors | Aerospace Defence and Marine Manufacturing including Industrial Biotechology |
Description | A W E Plc |
Amount | £70,000 (GBP) |
Funding ID | contract in preparation |
Organisation | Atomic Weapons Establishment |
Sector | Private |
Country | United Kingdom |
Start |
Description | A W E Plc |
Amount | £70,000 (GBP) |
Funding ID | contract in preparation |
Organisation | Atomic Weapons Establishment |
Sector | Private |
Country | United Kingdom |
Start |