The first data from the Orion laser: measurements of the spectrum of hot dense aluminium

8th International Conference on Inertial Fusion Sciences and Applications

Hoarty, D.J.^1 ; Allan, P.^1 ; James, S.F.^1 ; Brown, C.R.D.^1 ; Hobbs, L.M.R.^1 ; Hill, M.P.^1 ; Harris, J.W.O.^1 ; Morton, J.^1 ; Brookes, M.G.^1 ; Shepherd, R.^2 ; Dunn, J.^2 ; Chen, H.^2 ; Von Marley, E.^2 ; Beiersdorfer, P.^2 ; Chung, H.K.^3 ; Lee, R.W.^4 ; Brown, G.^3 ; Emig, J.^3

Dir. of Research and Applied Science, AWE Plc, Reading

RG7 4PR, United Kingdom^1

Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore

CA

94550, United States^2

Nuclear Data Nuclear Data Section, Division of Physical and Chemical Sciences, International Atomic Energy Agency, P. O. Box 100, Vienna

A-1400, Austria^3

Institute for Material Dynamics at Extreme Conditions, University of California, Berkeley, United States^4

关键词: Aluminium samples;    Ion-sphere model;    Laser driven shocks;    Measurements of;    Plasma conditions;    Short-pulse lasers;    Simulated spectra;    X-ray free electron lasers;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/688/1/012032/pdf
DOI  :  10.1088/1742-6596/688/1/012032

来源: IOP

【 摘 要 】

The newly commissioned Orion laser system has been used to study dense plasmas created by a combination of short pulse laser heating and compression by laser driven shocks. Thus the plasma density was systematically varied between 1 and 10g/cc by using aluminium samples buried in plastic foils or diamond sheets. The aluminium was heated to electron temperatures between 500eV and 700eV allowing the plasma conditions to be diagnosed by K- shell emission spectroscopy. The K-shell spectra show the effect of the ionization potential depression as a function of density via the delocalization of n=3 levels and disappearance of n=3 transitions in He-like and H-like aluminium. The data are compared to simulated spectra, which account for the change in the ionization potential by the commonly used Stewart and Pyatt prescription; a simple ion sphere model and an alternative due to Ecker and Kroll suggested by recent X-ray free-electron laser experiments. The experimental data are in reasonable agreement with the model of Stewart and Pyatt, but are in better agreement with a simple ion sphere model. The data indicate that the Ecker and Kröll model overestimates substantially the ionization potential depression in this regime.