## Temperature dependences of the rates of ((a)–(c)) ionization and ((d)–(f)) recombination of ((a) and (d)) W^{43 +}, ((b) and (e)) W^{44 +} and ((c) and (f)) W^{45 +}

**Figure 8.** Temperature dependences of the rates of ((a)–(c)) ionization and ((d)–(f)) recombination of ((a) and (d)) W^{43 +}, ((b) and (e)) W^{44 +} and ((c) and (f)) W^{45 +}. Results of these calculations are indicated by the black lines with the size of the model shown in each plot. In the plots of ionization rate, the rates calculated using the formula given by Asmussen *et al* [9], based on the ADPAK rates, are shown by the grey lines. In the plots of recombination rate, total, radiative and dielectronic recombination rates by Asmussen *et al* are shown by the grey lines.

**Abstract**

The fractional ion abundance and rates of ionization and recombination of multiple charged tungsten ions in magnetic fusion plasmas are investigated using a collisional radiative model. Using a computer algorithm to generate a set of atomic states to be included in the collisional radiative model, the dominant dielectronic recombination and excitation autoionization channels are determined by a systematic convergence analysis of the level population and ion abundance with respect to the size of the model. The atomic data, such as energy levels and rates of the radiative decay as well as autoionization, are obtained by the *ab initio* calculation using the Hebrew University Lawrence Livermore Atomic Code. The calculations are carried out in the temperature range of 100 eV–5 keV, and the ratio between the abundances of W^{44 +} and W^{45 +} ions agrees well with an experimental result obtained without any artificial adjustment of the atomic rates.