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Title: Progress in indirect and direct-drive planar experiments on hydrodynamic instabilities at the ablation front

Understanding and mitigating hydrodynamic instabilities and the fuel mix are the key elements for achieving ignition in Inertial Confinement Fusion. Cryogenic indirect-drive implosions on the National Ignition Facility have evidenced that the ablative Rayleigh-Taylor Instability (RTI) is a driver of the hot spot mix. This motivates the switch to a more flexible higher adiabat implosion design [O. A. Hurricane et al., Phys. Plasmas 21, 056313 (2014)]. The shell instability is also the main candidate for performance degradation in low-adiabat direct drive cryogenic implosions [Goncharov et al., Phys. Plasmas 21, 056315 (2014)]. This paper reviews recent results acquired in planar experiments performed on the OMEGA laser facility and devoted to the modeling and mitigation of hydrodynamic instabilities at the ablation front. In application to the indirect-drive scheme, we describe results obtained with a specific ablator composition such as the laminated ablator or a graded-dopant emulator. In application to the direct drive scheme, we discuss experiments devoted to the study of laser imprinted perturbations with special phase plates. The simulations of the Richtmyer-Meshkov phase reversal during the shock transit phase are challenging, and of crucial interest because this phase sets the seed of the RTI growth. Recent works were dedicated to increasingmore » the accuracy of measurements of the phase inversion. We conclude by presenting a novel imprint mitigation mechanism based on the use of underdense foams. The foams induce laser smoothing by parametric instabilities thus reducing the laser imprint on the CH foil.« less
Authors:
; ; ; ; ;  [1] ;  [1] ;  [2] ; ; ;  [3] ; ; ; ; ;  [4] ; ; ; ;  [5] more »;  [6] ; « less
  1. CEA, DAM, DIF, F-91297 Arpajon (France)
  2. (France)
  3. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
  4. Laboratory of Laser Energetics, Rochester, New York 14623-1299 (United States)
  5. CELIA, University of Bordeaux-CNRS-CEA, F-33400 Talence (France)
  6. Institute of Laser Engineering, Osaka University, Suita, Osaka 565 (Japan)
Publication Date:
OSTI Identifier:
22403367
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 12; Other Information: (c) 2014 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; FOAMS; INERTIAL CONFINEMENT; LASERS; MITIGATION; PLASMA; RAYLEIGH-TAYLOR INSTABILITY; THERMONUCLEAR IGNITION; US NATIONAL IGNITION FACILITY