Collisional-radiative Model Of The W⁴³⁺-W⁴⁵⁺ Ions Spectra

Tungsten is used as a divertor and wall material for magnetically confined fusion reactors（such as ITER,EAST,ASDEX-Upgrade,JET,etc.）because of its excellent physical,chemical and engineering thermophysical properties,such as high melting point,low sputtering rate and low deuterium-tritium retention.As armor material directly facing to the high temperature plasma,will be bombarded by the high temperature particle flow for a long time,which will inevitably produce the impurity tungsten ions and then be transported to the high temperature core region of plasma.Tungsten ions are further ionized into highly ionized tungsten ions in a high temperature fusion plasma.The radiation of high-energy photons by tungsten ions in the excited state may lead to energy loss,decrease of fusion plasma temperature and plasma quenching.However,a small amount of impurity tungsten ions are also used for plasma state diagnosis.Therefore,it is of great significance to study the distribution,transport,evolution and monitoring of tungsten impurity ions in fusion plasma.In order to do this,it is necessary to deeply understand the atomic structure,radiation properties and spectral information of various ionized tungsten ions.The spectra of W⁴³⁺-W⁴⁵⁺ions have been observed in EBIT and Tokamaks.However,there are only a few theoretical studies on these ions.The theoretical study of W⁴³⁺-W⁴⁵⁺ions is helpful to accurately identify the spectrum of W⁴³⁺-W⁴⁵⁺ions observed in the experiment.In this paper,the Flexible Atomic Code（FAC）program based on relativistic configuration interaction method is used to calculate the basic data of W⁴³⁺-W⁴⁵⁺ions atoms,construct and solve the appropriate collision radiation model,and theoretically calculate the spectra of W⁴³⁺-W⁴⁵⁺ions in EBIT and EAST.The main contents include:1.Considering the appropriate associated electron configuration,the basic atomic parameters such as energy level,radiative transition wavelength,transition rate and electron collision excitation cross section of W⁴³⁺-W⁴⁵⁺ions are calculated based on RCI method.the calculated results are in good agreement with the experimental results and other theoretical results.2.Taking into account the spontaneous emission transition,electron collision excitation and de-excitation process,the collision radiation model is constructed,and the theoretical spectra of W⁴³⁺-W⁴⁵⁺ions in EBIT and Maxwell plasma are calculated.Through the analysis of the population current of the energy level in the excited state,it is explained that the probability of the 4s²4p ²P_3/2-4s4p^{2 2}P_3/2,4s²4p ²P_3/2-4s4p^{2 4}P_5/2is large but not observed in the experiment,which is due to the small population flow of the energy level in the excited state.While the transition probability of 4s²4p ²P_1/2-4s4p^{2 4}P_1/2,4s²4p ²P_3/2-4s4p^{2 2}D_5/2,4s²4p ²P_3/2-4s²4p ²P_1/2 is small,but it can be observed in the experiment because of the large energy level population in the excited state.3.The charge state distribution of W⁴³⁺-W⁴⁵⁺ions under EAST experimental conditions is calculated,the synthesis spectrum of W⁴³⁺-W⁴⁵⁺ions is simulated,and the transition line of W⁴³⁺-W⁴⁵⁺ions is identified from the W-UTA of EAST plasma spectrum.4.On this basis,the dependence of W⁴³⁺-W⁴⁵⁺ions spectrum on electron temperature is studied,and some diagnostic lines which can be used for fusion plasma temperature diagnosis in the future are predicted.