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Ablative stabilization of the deceleration phase rayleigh-taylor instability
1Laboratory for Laser Energetics, Department of Mechanical Engineering, University of Rochester, Rochester, New York 14623, USA.
Physical Review Letters
|November 18, 2000
Summary
Finite ablation flow significantly reduces Rayleigh-Taylor instability growth rates in inertial confinement fusion capsules. This finding is crucial for optimizing direct-drive capsule designs at facilities like the National Ignition Facility.
Area of Science:
- Plasma Physics
- Nuclear Fusion
- Astrophysical Fluid Dynamics
Background:
- The Rayleigh-Taylor instability is a critical phenomenon in inertial confinement fusion (ICF) capsule implosions.
- Understanding and mitigating this instability is essential for achieving ignition.
- Previous models often simplified the complex physics of the ablative shell.
Purpose of the Study:
- To calculate the growth rates of deceleration-phase Rayleigh-Taylor instability in ICF capsules.
- To compare these calculated rates with results from advanced numerical simulations.
- To investigate the impact of finite ablation flow on instability spectrum and growth.
Main Methods:
- Theoretical calculations of instability growth rates.
- High-fidelity numerical simulations of imploding ICF capsules.
- Analysis of the unstable spectrum and growth rate dependence on ablation flow.
Main Results:
- Finite ablation flow at the shell's inner surface significantly reduces instability growth rates.
- The unstable spectrum of the Rayleigh-Taylor instability is also substantially diminished.
- A cutoff in the unstable spectrum is observed around l ≈ 90 for typical direct-drive capsules.
Conclusions:
- Finite ablation flow is a key stabilizing factor for Rayleigh-Taylor instability in ICF.
- The observed spectral cutoff has significant implications for capsule design and performance.
- Results provide crucial data for optimizing direct-drive ICF capsule designs for facilities like the National Ignition Facility.