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Effects of fuel-shell mix upon direct-drive, spherical implosions on OMEGA
C K Li1, F H Séguin, J A Frenje
1Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge 02139, USA.
Physical Review Letters
|October 26, 2002
Summary
Fuel-shell mix in direct-drive experiments significantly reduces implosion performance and convergence ratios (CR) compared to predictions. This mixing is identified as the likely cause for lower yields, particularly at lower fuel pressures.
Area of Science:
- * Nuclear fusion science
- * Plasma physics
- * High-energy-density physics
Background:
- * Direct-drive inertial confinement fusion (ICF) experiments at OMEGA utilize various capsule types.
- * Understanding fuel-shell mix is critical for optimizing ICF implosion performance.
Purpose of the Study:
- * To investigate the impact of fuel-shell mix on implosion performance in direct-drive ICF.
- * To quantify the extent of mixing and its correlation with reduced yields and convergence ratios (CR).
Main Methods:
- * Analysis of charged-particle spectrometry data to infer fuel-shell mix amount and region size.
- * Utilization of an experimentally constrained model to validate mix estimations.
- * Comparison of measured implosion yields and CR with one-dimensional (1D) predictions.
Main Results:
- * Measured CR values were approximately 11 across a range of 3-15 atm fill pressures.
- * Predicted CR values were significantly higher, reaching approximately 25 at 3 atm and 12 at 15 atm.
- * Implosion performance, including yields and CR, fell short of 1D predictions, especially at lower pressures.
Conclusions:
- * Fuel-shell mix is identified as the primary factor limiting implosion performance in these direct-drive experiments.
- * The observed discrepancies highlight the need for improved models that account for mixing effects in ICF capsule design.