Collisional-radiative Model Of The W ⅩⅣ-w ⅩⅦ Ions Spectra

Tungsten is selected as the divertor and plasma-facing material for magnetic confinement fusion reactors,such as ITER,EAST,and CFETR,due to its high melting point and high sputtering energy threshold,low sputtering rate and low deuterium/tritium retention rate.Meanwhile,the emission spectra of tungsten ions is beneficial to diagnose the high-temperature plasma parameters such as the electron temperature and electron density of fusion plasma.Therefore,investigation on the atomic structure,properties,kinetic process,and emission spectra of various tungsten ions has great significance for monitoring and controlling the flux of tungsten impurity and diagnosing the fusion plasma.In this thesis,the basic atomic data such as energy levels,transition energy and probability,and collisional excitation cross-sections were calculated using the Flexible Atomic Code（FAC）program based on the Relativistic Configuration Interaction（RCI）method.A reasonable Collisional-radiative model was constructed to study the EUV spectra of W¹³⁺–W¹⁶⁺ions and the visible spectra of W¹³⁺ions observed by electron beam ion trap（EBIT）.The main contents are as follows:1.The RCI method is used to calculate the atomic parameters such as the energy level,transition energy,spontaneous emission transition probability,and the electron collisional excitation cross section of W¹³⁺–W¹⁶⁺ions.The results are in reasonable agreement with the available experimental and theoretical data.2.An appropriate Collisional-radiative model has been constructed to calculate the 5p–5s and 5d–5p transitions of W¹³⁺ions with electron density of n_e=10¹⁰cm^-3in the EBIT plasma environment.The results are in reasonable agreement with the available experimental and theoretical data.The controversial spectra assignments from two independent experimental observation were identified.In the calculation,it was found that the transition probability of 5d–5p was generally large,but it was not observed in the previous experiment.The reason of the unobserved spectrum of 5d–5p transition of W¹³⁺ion in the EBIT was explained by analyzing the population of excited states.3.The 5p–5s transition of W¹⁴⁺and W¹⁵⁺ions were calculated.The results are in good agreement with the experimental results,and the transition corresponding to the experimental spectrum was identified.4.The 5p–5s transitions of W¹⁶⁺ion was predicted.It will provide detailed knowledge for future experimental and theoretical work.5.The M1 visible spectra of W¹³⁺ion in the range of electron density from n_e=10⁸cm^-33 to 10¹²cm^-33 are calculated.The M1 transition between the ground and low-lying excited state fine structure levels was found to be strongly dependent on the electron density.The controversy on the assignment of the M1 transition between the ground state of W¹³⁺ions from the different experiment was explained.Meanwhile,the intensity ratio of some strong transition lines of W¹³⁺ion is predicted,which might be applied for the diagnosis of the density of ITER plasma in the future.Finally,the dependence of the M1 transition spectrum of W¹³⁺ion on the electron density is explained by analyzing the population of the excited states.