Influence of a dense plasma on the fine-structure levels of a hydrogenic ion

We discuss the effects of plasma electron polarization surrounding a multiply charged hydrogenic impurity in a high density plasma on the fine-structure levels of the impurity ion. Calculations performed using the ion sphere model suggest that the magnitude of the fine-structure correction smoothly increases with increasing plasma electron density. The other features of the dense plasma effects include the removal of the k degeneracy of the Dirac levels, and a breakdown of the Z4 scaling of the fine-structure correction along the hydrogenic sequence of ions. The resultant outcome is a complete modification of the fine-structure multiplets in terms of the ordering and spacing between the multiplet components.