Demonstration of Scale-Invariant Rayleigh-Taylor Instability Growth in Laser-Driven Cylindrical Implosion Experiments

Area of Science:

• * High-energy-density physics
• * Hydrodynamic instabilities
• * Laser-driven implosions

Background:

• * Rayleigh-Taylor (RT) instability is a key phenomenon in inertial confinement fusion and astrophysical jets.
• * Understanding RT instability growth is crucial for predicting the performance of high-energy-density (HED) systems.
• * Previous studies have explored RT instability in various configurations, but scale invariance in convergent cylindrical implosions requires further investigation.

Purpose of the Study:

• * To investigate the hydrodynamic scale invariance of Rayleigh-Taylor instability growth in convergent cylindrical implosions.
• * To determine if instability growth is consistent across targets with varying radial dimensions and implosion timescales.
• * To validate predictions from radiation-hydrodynamics simulations in a controlled experimental setting.

Main Methods:

• * Direct laser irradiation of cylindrical targets to induce a short impulse.
• * Embedding an aluminum interface within a foam core to study instability growth.
• * Varying target radial dimensions and implosion timescales by a factor of 3.
• * Measuring instability growth as the interface converges radially inward by a factor of 2.25.

Main Results:

• * Hydrodynamic scale invariance of Rayleigh-Taylor instability growth was observed.
• * Late-time growth factors of 14 were consistently measured for a single-mode m=20 azimuthal perturbation at both scales.
• * Instability growth occurred despite differences in laser drive conditions between experimental facilities.
• * Results align with predictions from radiation-hydrodynamics simulations.

Conclusions:

• * Rayleigh-Taylor instability growth in this convergent cylindrical implosion platform exhibits hydrodynamic scale invariance.
• * The experimental platform is suitable for detailed investigations into the limits of hydrodynamic scaling in HED systems.
• * The findings support the predictive capabilities of radiation-hydrodynamics simulations for RT instability in relevant regimes.