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Title: Probing the deep nonlinear stage of the ablative Rayleigh-Taylor instability in indirect drive experiments on the National Ignition Facility

Academic tests in physical regimes not encountered in Inertial Confinement Fusion will help to build a better understanding of hydrodynamic instabilities and constitute the scientifically grounded validation complementary to fully integrated experiments. Under the National Ignition Facility (NIF) Discovery Science program, recent indirect drive experiments have been carried out to study the ablative Rayleigh-Taylor Instability (RTI) in transition from weakly nonlinear to highly nonlinear regime [A. Casner et al., Phys. Plasmas 19, 082708 (2012)]. In these experiments, a modulated package is accelerated by a 175 eV radiative temperature plateau created by a room temperature gas-filled platform irradiated by 60 NIF laser beams. The unique capabilities of the NIF are harnessed to accelerate this planar sample over much larger distances (≃1.4 mm) and longer time periods (≃12 ns) than previously achieved. This extended acceleration could eventually allow entering into a turbulent-like regime not precluded by the theory for the RTI at the ablation front. Simultaneous measurements of the foil trajectory and the subsequent RTI growth are performed and compared with radiative hydrodynamics simulations. We present RTI growth measurements for two-dimensional single-mode and broadband multimode modulations. The dependence of RTI growth on initial conditions and ablative stabilization is emphasized, and we demonstrate for the firstmore » time in indirect-drive a bubble-competition, bubble-merger regime for the RTI at ablation front.« less
Authors:
; ; ; ; ;  [1] ; ; ; ; ; ; ;  [2] ; ; ;  [3]
  1. CEA, DAM, DIF, F-91297 Arpajon (France)
  2. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
  3. General Atomics, San Diego, California 92121 (United States)
Publication Date:
OSTI Identifier:
22410398
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 5; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ABLATION; BUBBLES; COMPUTERIZED SIMULATION; EXPERIMENTAL DATA; HYDRODYNAMICS; INERTIAL CONFINEMENT; LASERS; MODULATION; NONLINEAR PROBLEMS; PHOTON BEAMS; PROBES; RAYLEIGH-TAYLOR INSTABILITY; STABILIZATION; TEMPERATURE RANGE 0273-0400 K; TWO-DIMENSIONAL CALCULATIONS; US NATIONAL IGNITION FACILITY