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A proposal to measure iron opacity at conditions close to the solar convective zone-radiative zone boundary

  • Hoarty, DJ
  • Morton, J
  • Jeffery, M
  • Pattison, LK
  • Wardlow, A
  • Mangles, SPD
  • Rose, SJ
  • Iglesias, C
  • Opachich, K
  • Heeter, RF
  • Perry, TS
Publication Date
May 14, 2019
Spiral - Imperial College Digital Repository


A major problem in stellar modelling is the discrepancy between solar models and helioseismology data in the position of the convective zone-radiative zone boundary in the sun. This could be explained by a large uncertainty in the calculated opacity data and recent experimental data on iron using the Sandia National Laboratory Z facility have shown large differences, up to a factor of 4, between measurement and prediction at plasma conditions close to the convective zone-radiative zone boundary. This paper describes a proposal for a radiative burn-through experiment to be fielded on NIF to observe if a radiation wave transit through a Fe2O3 sample is consistent with the factor of 2-4 change in the iron opacity seen in the Z experiments. A target design and the diagnostic method are described. A detailed radiation-hydrodynamic model has been used to generate synthetic results and explore the sensitivities and experimental accuracy needed for the proposed measurement.

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