Interspecies radiative transition in warm and superdense plasma mixtures

Abstract

Superdense plasmas widely exist in planetary interiors and astrophysical objects such as brown-dwarf cores and white dwarfs. How atoms behave under such extreme-density conditions is not yet well understood, even in single-species plasmas. Here, we apply thermal density functional theory to investigate the radiation spectra of superdense iron-zinc plasma mixtures at mass densities of ρ = 250 to 2000 g cm −3 and temperatures of kT = 50 to 100 eV, accessible by double-shell-target implosions. Our ab initio calculations reveal two extreme atomic-physics phenomena-firstly, an interspecies radiative transition; and, secondly, the breaking down of the dipole-selection rule for radiative transitions in isolated atoms. Our first-principles calculations predict that for superdense plasma mixtures, both interatomic radiative transitions and dipole-forbidden transitions can become comparable to the normal intra-atomic Kα-emission signal. These physics phenomena were not previously considered in detail for extreme high-density plasma mixtures at super-high energy densities.

Probing atomic physics at ultrahigh pressure using laser-driven implosions

“…Energy band shifting and ionization balance are self-consistently described, without invocation of an ad hoc continuum lowering model. This model development is based on the preliminary success of treating warm-dense plasmas as quantum many-body systems [39][40][41][42][43][44] with mean-field DFT.…”

Non-empirical Mixing Coefficient for Hybrid XC Functionals from Analysis of the XC Kernel

“…Clearly, there is ample room left for the variation of the degree of mixing and of the screening parameter for systems different from molecules under ambient conditions. The situation is particularly unsatisfactory for WDM, where such basic atomic properties like an atomization energy become ill defined due to the smearing of the boundary between bound and free states at high pressure or temperature, − and where bulk properties such as the vacancy formation energy or bulk moduli cannot be accurately measured due to prevalent extreme conditions. Moreover, the bulk properties of materials like the lattice constant (interparticle distance and/or separation), stress tensor, etc., at high pressures and temperatures often differ significantly from those under ambient conditions.…”