Fourier Transform Method Of A Detailed Configuration Accounting In Hot Plasma Bound-Bound Opacity Calculations
Evgeniya Arapova, Yulia Koryakina, Mikhail Vronskiy
TL;DR
This work tackles accurate bound-bound opacity in hot plasmas by extending the Hazak–Kurzweil Fourier-transform configurational-resolution framework to Detailed Configuration Accounting (DCA). The approach yields closed-form, numerically efficient expressions by exploiting a factorized, probabilistic shell-occupation model and a time-domain (Fourier) treatment of transition arrays. Through DCA, DCA+UTA, and DCAeff+UTAeff schemes, the method captures configurational fluctuations and broadening mechanisms, aligning well with experimental spectra for several elements while highlighting the limitations of simpler, averaged treatments. The results demonstrate a practical path to configurationally resolved opacities that can adapt to different one-electron state descriptions and broadening models, with potential for broad applicability in high-energy-density plasma modeling.
Abstract
G.~Hazak and J.~Kurzweil discovered a method of configurational resolution of transition arrays for the Super Transition Arrays approach to the bound-bound opacity calculation. Their method is based on the representation of the photoabsorption coefficient as the Fourier transform, the linearity of the transition energy between configurations with respect to shell occupation numbers, and factorization of the probabilities of configurations on shell occupation numbers. We extend the Hazak -- Kurzweil method for the calculations with Detailed Configuration Accounting. The resulting expressions for the bound-bound opacity represent an alternative to the widely used ones and are quite convenient for numerical implementation.