2D X-ray radiography of imploding capsules at the national ignition facility

Phys Rev Lett. 2014 May 16;112(19):195001. doi: 10.1103/PhysRevLett.112.195001. Epub 2014 May 12.

Abstract

First measurements of the in-flight shape of imploding inertial confinement fusion (ICF) capsules at the National Ignition Facility (NIF) were obtained by using two-dimensional x-ray radiography. The sequence of area-backlit, time-gated pinhole images is analyzed for implosion velocity, low-mode shape and density asymmetries, and the absolute offset and center-of-mass velocity of the capsule shell. The in-flight shell is often observed to be asymmetric even when the concomitant core self-emission is round. A ∼ 15 μm shell asymmetry amplitude of the Y(40) spherical harmonic mode was observed for standard NIF ICF hohlraums at a shell radius of ∼ 200 μm (capsule at ∼ 5× radial compression). This asymmetry is mitigated by a ∼ 10% increase in the hohlraum length.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Computer Simulation
  • Germanium / chemistry
  • Gold / chemistry
  • Models, Theoretical*
  • Radiography / methods*
  • Thermodynamics
  • X-Rays

Substances

  • Germanium
  • Gold