On the Accuracy of X-Ray Spectra Modeling of Inertial Confinement Fusion Plasmas
We have performed x-ray spectroscopic experiments in homogeneous gas bag plasmas where we independently measure the temperature with Thomson scattering. We find that collisional radiative (kinetics) modeling of the intensities of the He-{beta} line and its dielectronic capture satellites is generally in agreement with the measured spectra. On the other hand, for the particular case of satellites arising from inner-shell electron collisional excitation, we find discrepancies of up to a factor of two between experiment and kinetics models. We have ruled out possible effects on the line emission due to plasma gradients, radiative transport, and suprathermal electron excitation leaving errors in the atomic physics modeling to be the most likely explanation. The determination that there are problems with the collisionally populated states is important for the interpretation of inertial confinement fusion capsule implosions where electron densities and temperature have been measured using the spectral line shape of the He-{beta} transition of Ar XVII. The analysis of the implosion data has required Stark broadening calculations coupled to a kinetics model to calculate the detailed line intensities and widths. Despite remaining discrepancies, the good agreement between the experimental dielectronic capture satellites and the HULLAC calculations suggests that HULLAC is a more appropriate code for the construction of the kinetics models of the He-{beta} complex from high density plasmas than previously used codes (e.g. MCDF). HULLAC results in higher temperatures for the implosion conditions of Ref.(5,6) in closer agreement with the 2-D radiation hydrodynamic modeling and other spectroscopic techniques. These results indicate that benchmarking kinetics codes with Thomson scattering is an important area in present ICF research.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE Office of Defense Programs (DP) (US)
- DOE Contract Number:
- W-7405-Eng-48
- OSTI ID:
- 792811
- Report Number(s):
- UCRL-JC-137557; TRN: US0300613
- Resource Relation:
- Journal Volume: 547; Conference: 12th APS Topical Conference on Atomic Processes in Plasmas, Reno, NV (US), 03/19/2000--03/23/2000; Other Information: PBD: 30 May 2000
- Country of Publication:
- United States
- Language:
- English
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