Regular Article

Critical free electron densities and temperatures for spectral lines in dense plasmas

¹ Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, P.R. China
² College of Electrical Engineering, Longdong University, Qingyang 745000, P.R. China
³ Key Laboratory of High Energy Density Physics and Technology, Ministry of Education, Chengdu 610065, P.R. China

^a e-mail: gjiang@scu.edu.cn

Received: 29 January 2018
Received in final form: 21 June 2018
Accepted: 17 August 2018
Published online: 11 October 2018

Abstract

The ionization potentials of bound electrons decrease when an atom is immersed in plasma. The calculation or measurement of the ionization potential depression (IPD) is used to estimate the influence of the plasma environments on atomic structures. This work reports a simple method for the estimation of the effects of IPD on H- and He-like ions in dense plasmas. The method predicts the critical free electron densities and temperatures after which spectral lines of H- and He-like ions disappear. The critical free electron density and temperature are the free electron density and temperature that correspond to the classical turning point radius of a bound electron in the highest occupied orbital of the two atomic states for a transition that is equal to the ion-sphere radius. The obtained critical free electron densities are in better agreement with the ORION experimental results than those obtain using other available theories. The present method may thus provide a more accurate estimation of the effects of IPD in dense plasmas and may be extended to other multi-electron ions such as Li- and Be-like ions.