Emission spectra of Warm Dense Matter plasmas

Warm Dense Matter (WDM) is a highly transient state of material between cold condensed matter and dense plasmas. In this work, we have investigated the confinement of carbon ions in the WDM regime and the emission in spectral lines for WDM copper in a range of plasma temperatures and densities using the developed collisional-radiative equilibrium model that includes the effects of dense plasma on radiative properties. The 2s and 2p orbitals and charge density of carbon ions are found to be severely distorted at near-solid density. It is observed for WDM copper that with the increase of temperature, spectral lines disappear in infrared and visible spectrum regions and appear in ultraviolet and soft x-ray regions. At temperature >5 eV and low density (<0.1 g/cm³), a significant amount of radiation is emitted in x-ray spectral lines. With the increase of mass density of WDM copper, the change in line shapes, their broadening and shifts are observed. At mass density of ∼0.1 g/cm³, the number of spectral lines is reduced, and completely disappear above solid density.