Investigation Of Radiation Properties Of Highly-charged Ions In Laser-produced Ni And Zn Plasmas

Laser-produced plasma contains a large number of highly-charged ions with multiple charge states when a high power laser pulse was focused on a solid target.Such highlycharged ions have many open sub-shells,involved a large number of near-merging levels,and emit strong radiation in the extreme ultraviolet band.Their spectral structures are very complex and generally show quasi-continuous or narrow-band characteristics.The in-depth study of the radiation characteristics of highly-charged ions will not only help to reveal the radiation and dynamic behavior of complex atoms(ions)in plasma environment,but also provide important data and methodological support for the researches of pulsed short-wave light sources,high-current ion sources and astrophysics plasmas.Narrow-band radiation of laser-produced plasma in extreme ultraviolet band has the potential important applications in soft x-ray light source and extreme ultraviolet lithography source,which have attracted the interests of many researchers.In this paper,zinc(Zn)and nickel(Ni)elements were selected to carry out the following experimental and theoretical studies:(1)The extreme ultraviolet(EUV)emission spectra of Zn and Ni plasmas at different delay time and different spatial locations were measured using a high-precision spatiotemporally resolved laser-produced emission plasma spectroscopy.The evolution of dominant band-like spectral characteristics with time and space was analyzed,and the differences between both spectral structures were compared and analyzed.(2)In order to overcome the shortage of atomic structure parameters of highlycharged Zn and Ni ions in the process of spectral feature recognition,the possible charge state distribution were estimated based on a steady-state collisional-radiative model,the energy level transitions of corresponding ions were calculated using an atomic structure calculation program,and plasma parameters were estimated by comparing experimental and simulated spectra,based on the assumption of a normalized Boltzmann distribution among excited states and a collisional-radiative model.Through further comparison and analysis with the experimental spectral characteristics,it is determined that the dominant characteristics of experimental spectra arise from the contributions of 3p-3d and 3d-4f transition arrays of Zn,Ni ions.The data of energy level structures and transitions of the related ions are obtained,and the diagnosis of plasma state parameters is realized.The results provide further understanding of radiation properties of highly charged ions of middle-and high-Z elements.