Abstract
In 2009 a series of metal-lined hohlraums were tested on the Omega laser facility. The main aims of the campaign were to improve our understanding of the multi-keV energy production and our capability to numerically reproduce the measured conversion efficiencies (CE's). Two studies have been primarily planned: the effect of the metallic plasma mean ionization states and that of hydrodynamics. Six targets were experimented for which the metallic materials (titanium, copper, germanium), the cavity diameter, and the irradiation energy were varied. Here we compare experimental and calculated results. The numerical simulations are performed with the 2D hydro-radiative code FCI2. For all the cavities, the measured multi-keV x-ray powers versus time are qualitatively well reproduced by the simulations, indicating that hohlraum hydrodynamics seems to be well calculated. But we have an underestimation by a factor of ∼2 for the calculated CEs versus experimental values for titanium and copper hohlraums. By contrast there is a good agreement between measurements and calculations for the germanium hohlraum. To explain these results, we have calculated off-line integrated emissivities for couples of (ρ, Te) values contributing to the multi-keV production with several non-local-thermal-equilibrium (NLTE) atomic physics models.
Highlights
Multi-keV x-ray sources are required for diagnostics of inertial confinement fusion (ICF) experiments and material testing
We have successfully tested a new series of metal-lined cavities on Omega in 2009
A rather good qualitative agreement is obtained between diagnostic data and simulation results for time-dependant x-ray powers and images, indicating that the cavity hydrodynamics seems to be well calculated
Summary
Multi-keV x-ray sources are required for diagnostics of inertial confinement fusion (ICF) experiments and material testing. To improve the CE’s, new source principles have been considered as metal-doped aerogel targets [4, 5], pre-pulsed thin metallic foils [6] and metal-lined hohlraums which are plastic cylinders coated with metallic materials. A new campaign has been carried out in 2009 on Omega with the aim of studying and improving our capability to reproduce x-ray production of such metal-lined sources with our numerical tools and physical models. We had imaging systems, XRFC and XRPHC, to observe the x-ray emission volumes with and without temporal resolution
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