Theoretical Investigation Of Dielectronic Recombination For Rh-like Isoelectronic Sequence And Sr-like Tungsten Ions

Dielectronic recombination?DR?process is a very important process in electron-ion collisions,it widely exists in laboratory plasma and astronomy plasma,and plays an important role in establishing and maintaining plasma ionization equilibrium and excitation ion distribution.Accurate DR rate coefficients are crucial for diagnosing plasma temperature and density and simulating plasma environment.In this paper,the DR process of Rh-like isoelectronic sequence ions and the DR process of Sr-like tungsten(W³⁶⁺)ions are studied by using the Flexible Atomic Code?FAC?package based on the fully relativistic configuration-interaction method,the main contents include:Firstly,the DR process of Rh-like isoelectronic sequence ions is studied in detail.In order to systematically study,find and summarize the regularity of various effects and DR rate coefficients with atomic number Z,the DR rate coefficients of 15 Rh-like isoelectronic sequences(Sn⁵⁺,Sb⁶⁺,Te⁷⁺,Xe⁹⁺,Ba¹¹⁺,Gd¹⁹⁺,Tb²⁰⁺,Hf²⁷⁺,Ta²⁸⁺,W²⁹⁺,Re³⁰⁺,Os³¹⁺,Au³⁴⁺,Hg³⁵⁺,Tl³⁶⁺)are calculated by FAC package.All levels of the doubly excited states 4d⁸nln'l'and 4p⁵nln'l'?n=4,5,6,n'<24,l'<12?are considered and extrapolated to n'=1000.The effects of excitation channel,radiation channel,resonant stabilizing?RS?transition,nonresonance stabilizing?NRS?transition and radiative cascades?DAC?on DR rate coefficients were investigated,and the regularity of various effects was revealed.It is found that with the increase of atomic number Z,and the contribution of DAC effect decreases gradually.When Z=50,the maximum contribution of DAC effect is 81.92%in the whole temperature range.When Z=81,the maximum contribution of DAC effect is 19.98%in the whole temperature range,which is still not negligible.The deviation between the calculated values considering only NRS+RS and those considering DAC effect contribution is less than 13.40%.With the increase of atomic number Z,the total DR rate coefficient increases and the peak value moves to high temperature gradually.The DR rate coefficients of the ground state and first excited state are fitted and the fitting parameters are obtained.The regularity of DR rate coefficients with atomic number is summarized.An empirical formula for the regularity of DR rate coefficients at high temperatures in ground state is obtained for easy to use.Secondly,the DR process of W³⁶⁺ions are studied.The ground configuration of W³⁶⁺ions is[Zn]4p⁶4d²with nine energy levels.The present calculations include the DR contributions of all of the levels in the inner-shell excited configurations[Zn]4p⁵4d³nln'l'and[Zn]4p⁶4d¹nln'l'?n=4,5,6,n'=4-1000,l'<12?.The contributions of all dominant radiative decays from particular levels to lower autoionizing levels possibly followed by DAC are also estimated.It is found that with the increase of temperature,the contribution of DAC effect becomes more and more important.At650eV,the contribution of DAC effect is 11.67%,and the calculated value of DR rate coefficient considering DAC effect is 4.53%different from that considering NRS+RS.At 50000 eV,the contribution of DAC effect is the largest,19.34%,which is 5.03%different from the calculated value of NRS+RS.Finally,the DR rate coefficients of nine levels of ground configuration are fitted for convenience.