Relativistic calculations of fine-structure energy levels of He-like Ar in dense plasmas

The fine-structure energy levels of 1 s2s and 1 s2p atomic states for the He-like Ar ion immersed in dense plasmas are calculated. The ion sphere model is used to describe the plasma screening effect on the tested ion. The influences of the hard sphere confinement and plasma screening on the fine-structure energy levels are investigated respectively. The calculated results show that the confined effect of the hard sphere on the fine-structure energy levels increases with decreasing hard sphere radius, and the plasma screening effect on the fine-structure energy levels increases with the increase of free electron density. In dense plasmas, the confined effect of the hard generally, compared with the contribution from free electron crossing is found among 1 s2s （1 So） and 1 s2p （3P0,1） atomic plasma diagnostics. sphere on the fine-structure energy levels can be neglected screening. An interesting phenomenon about the energy level states. The results reported at the present work are useful for