Theoretical Investigation On Electric Dipole、Magnetic Dipole Transition Spectrum Of W⁵⁴⁺ Ion

Tungsten（W）had been used as armor material for the plasma facing component in divertor region and wall of International Thermonuclear Experiment Reactor（ITER）for its favorite chemical,physical,and engineering thermal physics properties such as,high melting point（3695 K）,good thermal conductivity,low deuterium-tritium sputtering rate and retention rate,low deuterium-tritium deposition effect.In fusion,the edge plasma will inevitably interact with the tungsten wall and possibly ionize the tungsten atom in the wall into ions.These tungsten ions might be transported to the fusion core plasma with high temperature,and be ionized further to produce highly charged tungsten ions.Tungsten ions cannot be fully ionized even in the extremely high temperature（T_e=25 keV）of ITER fusion plasmas.These highly ionized tungsten ions will emit high energy photons（such as EUV rays and X-rays）.Consequently,a large radiation loss could be caused by these highly charged impurity ions,which will lead to plasma disuiption if the relative concentration of tungsten ions in the core plasma is higher than about 10^-5.Therefore,the monitoring and controlling of the flux of these tungsten impurity ions will be very important to retain fusion reaction.To the basic knowledge of tungsten,the energy level,transition properties,and the spectrum of tungsten ions are extremely valuable.In the present thesis,theoretical study on the electric dipole（E1）、magnetic dipole（M1）transition spectrum between ground state（[Ne]3s²3p⁶3d²）and the first excited states（[Ne]3s²3p⁵3d³）of W⁵⁴⁺ions are carried out by using the flexible Atomic Code（FAC）package which is based on the relativistic interaction method（RCI）.The main contents of the present thesis are as follows:1、Based on the application of magnetic confinement fusion,it is of great scientific significance and potential practical application to study the basic data of tungsten ions,such as energy levels,radiative transition and spectrum properties.The basic atomic data of W⁵⁴⁺ions was calculated by using the RCI method.2、The basic atomic data such as the energy levels,the radiative transition rates and the collisional excitation cross section of the first excited states（[Ne]3s²3p⁵3d³）and the ground state（[Ne]3s²3p⁶3d²）of W⁵⁴⁺are calculated by RCI method.An appropriate collisional-radiative model was constructed under quasi steady-state approximation for EBIT and LTE plasma by include the spontaneous radiative transition and collisional（de）excitation process.The intensity of the E1 and M1 transitions spectrum in the EBIT and LTE plasm were calculated and the results of the calculations well reproduce the E1 and M1 transition spectrums previously observed in different EBIT experiments.The present results confirmed that previous observed 3transitions in EBIT with wavelengths 31.400?,31.522?,31.787?were the E1 transitions from levels of the first excited configuration（[Ne]3s²3p⁵3d³）to the ground configuration（[Ne]3s²3p⁶3d²）oftheW⁵⁴⁺suchas[((3p2_1/23p3_3/2)3/2(3d2_3/2)0)3/23d5/2]3→[3p63d2_3/2]2,[((3p2_1/23p3_3/2)3/2(3d2_3/2)2)5/23d5/2]2→[3p⁶3d²_3/2]₂,[((3p²_1/23p³_3/2)_3/2(3d²_3/2)₂)_7/23d_5/2]₁→[3p⁶3d²_3/2]_2.Meanwhile,the population mechanics was analyzed for the transitions with large transition rates but not observed in the previous experiment.3、Further research on the M1 spectrum were done based on the similar calculation.The 3 observed M1 transitions with wavelengths 14.986 nm,17.144 nm,19.268 nm are confirmed from the levels of the ground state（[Ne]3s²3p⁶3d²）of W⁵⁴⁺such as（3/2,5/2）₂→（3/2,3/2）₂,（3/2,5/2）₃→（3/2,3/2）₂,（3/2,5/2）1→（3/2,3/2）_0,respectively.A possible transition with wavelength 14.154 nm was predicted observable in the similar experimental conditions.Some other possible E1,M1 transition lines were predicted to be observable in the future EBIT experiments or fusion plasma experiments.