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Title: Early time implosion symmetry from two-axis shock-timing measurements on indirect drive NIF experiments

An innovative technique has been developed and used to measure the shock propagation speed along two orthogonal axes in an inertial confinement fusion indirect drive implosion target. This development builds on an existing target and diagnostic platform for measuring the shock propagation along a single axis. A 0.4 mm square aluminum mirror is installed in the ablator capsule which adds a second orthogonal view of the x-ray-driven shock speeds. The new technique adds capability for symmetry control along two directions of the shocks launched in the ablator by the laser-generated hohlraum x-ray flux. Laser power adjustments in four different azimuthal cones based on the results of this measurement can reduce time-dependent symmetry swings during the implosion. Analysis of a large data set provides experimental sensitivities of the shock parameters to the overall laser delivery and in some cases shows the effects of laser asymmetries on the pole and equator shock measurements.
Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;  [1] ; ;  [2] ;  [3]
  1. Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)
  2. General Atomics, San Diego, California 92186-5608 (United States)
  3. Laboratory for Laser Energetics, Rochester, New York 14623-1299 (United States)
Publication Date:
OSTI Identifier:
22303642
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 9; 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; ALUMINIUM; CAPSULES; IMPLOSIONS; INERTIAL CONFINEMENT; LASERS; SENSITIVITY; SYMMETRY; TIME DEPENDENCE; US NATIONAL IGNITION FACILITY; X RADIATION