Collisional-Radiative Model For The Spectrum Of W²⁶⁺ And W⁶⁺ions

With the development of the economy and society, the demand on energy is imperative. Fusion is one of the most promising energy source of providing safe, efficient and clean new energy. There are two branches of implements for stable fusion reactions, the one is Inertial Confinement Fusion ?ICF?, one of the typical devices is the National Ignition Facility ?NIF? in U.S., the other is Magnetic Confinement Fusion ?MCF? based on TOKMAK, the International Thermonuclear Experimental Reactor ?ITER? is one of the most famous example for the latter. Magnetic confinement fusion is considered to be a promising method. Tungsten ?W? was selected as the cover material of the ITER first wall and the divertor due to its special thermal engineering and stable physical properties, such as high melting point, good thermal conductivity, low sputtering for tritium and deuterium, low tritium deuterium retention rate etc.. However, tungsten impurity ions might inevitably be produced during the interaction between the edge plasma and cover material. These impurity ions may be transported to the fusion core plasma, and be ionized further to produce highly charged W ions. These highly charged W ions will cause large radiation loss by emitting high energy photons, which will lead to plasma disruption if the relative concentration of W ions in the core plasma is higher than about 10^-5. Thus, monitoring and controlling of tungsten impurity ions flow is very crucial to achieve and retain a stable fusion. Nevertheless, tiny amount of tungsten impurity ions can also provide us with plenty of information about fusion plasmas such as electron density, electron temperature and ion temperature by their spectrum.Based on the theory of full relativistic configuration interaction ?RCI? method with the implementation of Flexible Atomic Code ?FAC? packages, the energy level, radiation transition rate and electron impact excitation cross section of the W²⁶⁺and W⁶⁺ions were calculated. And the collision radiation ?CR? model was constructed and solved under the quasi static approximation. The spectrum was calculated at different plasma parameters. The present results make a good agreement with the experiments. Meanwhile, some important transitions were identified and predicted, such as the Ml transition ³H₅?³H₄ of W²⁶⁺ ions with the wavelength 389.4 nm,and E1 transitions f¹⁴p⁶¹S0?p⁵5d?2/1,2/3?,and f¹⁴p⁶¹S?p⁵5d?2/3,3/5?1 of W⁶⁺ ions with the wavelength of 216.219??? and 261.387???,respectively.Additionally,some transition arrays were suggested to serve as potential diagnostic lines for EBIT?Electron Beam Ion Trap? and fusion plasma.