Simulating x-ray Thomson scattering signals from high-density, millimetre-scale plasmas at the National Ignition Facility

Journal Article · Fri Aug 15 00:00:00 EDT 2014 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4893146· OSTI ID:22303784

Kraus, D.; Falcone, R. W. ^[1]; Kritcher, A. L.; Bachmann, B.; Collins, G. W.; Gaffney, J. A.; Hawreliak, J. A.; Landen, O. L.; Le Pape, S.; Ma, T.; Nilsen, J.; Pak, A.; Swift, D. C.; Döppner, T. ^[2]; Gericke, D. O. ^[3]; Glenzer, S. H. ^[4]; Guymer, T. M. ^[5]; Neumayer, P. ^[6]; Redmer, R. ^[7]; others, and

---

1. Department of Physics, University of California, Berkeley, California 94720 (United States)
2. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
3. Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry CV4 7AL (United Kingdom)
4. SLAC National Accelerator Laboratory, Menlo Park, California 94309 (United States)
5. Plasma Physics Group, Radiation Physics Department, AWE plc, Reading RG7 4PR (United Kingdom)
6. Gesellschaft für Schwerionenforschung, 64291 Darmstadt (Germany)
7. Institut für Physik, Universität Rostock, 18051 Rostock (Germany)

We have developed a model for analysing x-ray Thomson scattering data from high-density, millimetre-scale inhomogeneous plasmas created during ultra-high pressure implosions at the National Ignition Facility in a spherically convergent geometry. The density weighting of the scattered signal and attenuation of the incident and scattered x-rays throughout the target are included using radial profiles of the density, opacity, ionization state, and temperature provided by radiation-hydrodynamics simulations. These simulations show that the scattered signal is strongly weighted toward the bulk of the shocked plasma and the Fermi degenerate material near the ablation front. We show that the scattered signal provides a good representation of the temperature of this highly nonuniform bulk plasma and can be determined to an accuracy of ca. 15% using typical data analysis techniques with simple 0D calculations. On the other hand, the mean ionization of the carbon in the bulk is underestimated. We suggest that this discrepancy is due to the convolution of scattering profiles from different regions of the target. Subsequently, we discuss modifications to the current platform to minimise the impact of inhomogeneities, as well as opacity, and also to enable probing of conditions more strongly weighted toward the compressed core.

• OSTI ID: 22303784
• Journal Information: Physics of Plasmas, Vol. 21, Issue 8; Other Information: (c) 2014 Crown; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ABLATION
DATA ANALYSIS
IMPLOSIONS
INHOMOGENEOUS PLASMA
IONIZATION
SIGNALS
SIMULATION
THOMSON SCATTERING
X RADIATION