Average-atom calculations of bound-free and free-free cross sections in dense plasmas

W. R. Johnson and Joseph Nilsen
Phys. Rev. E 102, 043209 – Published 14 October 2020

Abstract

Cross sections for photo-induced bound-free and free-free transitions in plasmas are evaluated in the average-atom approximation and applied to determine opacities of dense plasmas of light elements. Parameters characterizing the plasmas (chemical potential, average ionic charge, free electron density, bound and continuum wave functions, and occupation numbers) are obtained from the average-atom model. Lowest-order calculations of the free-free cross sections, which diverge in the low-frequency limit, are regularized by accounting for the finite electron-ion relaxation time. The resulting analysis provides the basis for average-atom studies of plasma opacities. Such studies are presented for dense lithium, beryllium, boron, and carbon. Applications are given to Rosseland mean opacities of dense hydrogen and deuterium plasmas and to comparisons of free-free to bound-free opacities in shock-compressed plasmas. Average-atom cross section and opacity calculations are extended to plasmas consisting of more than one ionic species, boron nitride, polystyrene, and a composite H, He, C plasma.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
1 More
  • Received 6 August 2020
  • Revised 12 September 2020
  • Accepted 25 September 2020

DOI:https://doi.org/10.1103/PhysRevE.102.043209

©2020 American Physical Society

Physics Subject Headings (PhySH)

Plasma Physics

Authors & Affiliations

W. R. Johnson*

  • Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, Indiana 46556, USA

Joseph Nilsen

  • Lawrence Livermore National Laboratory, Livermore, California 94551, USA

  • *johnson@nd.edu
  • jnilsen@llnl.gov

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 102, Iss. 4 — October 2020

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review E

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×