The use of geometric effects in diagnosing ion density in ICF-related dot spectroscopy experiments

Journal Article · 27 January 2019 · High Energy Density Physics

DOI: https://doi.org/10.1016/j.hedp.2019.01.005 · OSTI ID:1841838

Pérez-Callejo, G.  ^[1]; Liedahl, D. A. ^[2]; Schneider, M. B. ^[2]; Rose, S. J. ^[3]; Wark, J. S. ^[1]

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1. Univ. of Oxford (United Kingdom)
2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
3. Univ. of Oxford (United Kingdom); Imperial College, London (United Kingdom)

Here, we describe a method to calculate the ion density of High Energy Density (HED) cylindrical plasmas used in dot spectroscopy experiments. This method requires only spectroscopic measurements of the Heα region obtained from two views (Face-on and Side-on). We make use of the fact that the geometry of the plasma affects the observed flux of optically thick lines. The ion density can be derived from the aspect ratio (height-to-radius) of the cylinder and the optical depth of the Heα-y line (1s2p ³P₁ → 1s^{2 1}S₀). The aspect ratio and the optical depth of the y line are obtained from the spectra using ratios measured from the two directions of emission of the optically thick Heα-w line (1s2p ¹P₁ → 1s^{2 1}S₀) and the ratio of the optically thick to thin lines. The method can be applied to mid-Z elements at ion densities of 10¹⁹– 10²⁰ cm^-3 and temperatures of a the order of keV, which is a relevant regime for Inertial Confinement Fusion (ICF)

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE; USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 1841838
• Report Number(s): LLNL-JRNL--758489; 946696
• Journal Information: High Energy Density Physics, Journal Name: High Energy Density Physics Journal Issue: N/A Vol. 30; ISSN 1574-1818
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English