Experiments on the Scaling of Ionization Balance vs. Electron and Radiation Temperature in Non-LTE Gold Plasmas
Understanding and predicting the behavior of high-Z non-LTE plasmas is important for developing indirect-drive inertial confinement fusion. Extending earlier work from the Nova laser, we present results from experiments using the Omega laser to study the ionization balance of gold as a function of electron and radiation temperature. In these experiments, gold samples embedded in Be disks expand under direct laser heating to n{sub e} {approx} 10{sup 21} cm{sup -3}, with T{sub e} varying from 0.8 to 2.5 keV. An additional finite radiation field with effective temperature T{sub r} up to 150 eV is provided by placing the gold-Be disks inside truncated 1.2 mm diameter tungsten-coated cylindrical hohlraums with full laser entrance holes. Densities are measured by imaging of plasma expansion. Electron temperatures are diagnosed with either 2 {omega} or 4 {omega} Thomson scattering, and also K-shell spectroscopy of KCl tracers co-mixed with the gold. Hohlraum flux and effective radiation temperature are measured using an absolutely-calibrated multichannel filtered diode array. Spectroscopic measurements of the M-shell gold emission in the 2.9-4 keV spectral range provide ionization balance and charge state distribution information. The spectra show strong variation with T{sub e}, strong variation with the applied T{sub r} at T{sub e} below 1.6 keV, and relatively little variation with T{sub r} at higher T{sub e} (upwards of 2 keV). We summarize our most recent spectral analyses and discuss emerging and outstanding issues.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15014388
- Report Number(s):
- UCRL-PROC-205149; TRN: US0802130
- Resource Relation:
- Journal Volume: 730; Conference: Presented at: 14th APS Topical Conference on Atomic Processes in Plasmas, Santa Fe, NM, United States, Apr 19 - Apr 22, 2004
- Country of Publication:
- United States
- Language:
- English
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