Spectra of W VIII and W IX in the EUV Region

The results obtained on the W VIII spectrum as well as on the isoelectronic spectra Lu V, Hf VI, Ta VII, and Re IX in the VUV wavelength region are summarized with emphasis on the main trends along the isoelectronic sequence. A total of 187 lines of W VIII in the region of 160–271 Å were accurately measured and identified, 98 levels were found, and transition probabilities calculated. The isoelectronic regularities support the data on W VIII. A list of spectral lines in the region of 170–199 Å, considered as belonging to W IX, is presented.

Rigorous selection rules for electric dipole transitions are: 1.One electron jumping, with Δl = ± 1 2. Parity change 3. ΔJ = 0, ± 1 (except 0 0) An electric dipole transition with violation of any of these selection rules is considered as forbidden.Different physical processes can break some of these rules.In our case, the configuration interactions, mixing the wave functions of different configurations, result in a presence of forbidden lines, what is mentioned in lines 137-138.They violate the rule 1.In the case of the 4f 12 5s 2 5p 6 6s configuration (lines 243-245), the transitions to the 4f 14 5s 2 5p 5 configuration represent a two electron jump and in the transitions to the 4f 13 5s 2 5p 6 configuration, Δl = 3 (4f -6s)

Reviewer 2: Report and Author Response
The manuscript includes valuable data on WVIII and WIX which will be useful for fusion research.The experimental data are also compared with calculation giving their transitions and wavelengths.Then, it should be published in Atoms after improving minor points suggested below.0. The authors have already published several tungsten spectra Phys.Scr.Please explain clearly in the introduction the different point compared to the papers which were already published.It is quite difficult for readers to understand. 1. Line 34: "Tungsten sputtered from the wall" should be replaced by " Tungsten sputtered from the divertor".2. Line 89: What is the wavelength range observed by normal incidence spectrograph?3. Line 152: "Thelines" needs a space, i.e. "The lines".
Line 181: Uncertainties in the observed wavelength should be indicated in the table captions of  Table 1, 2 and 4. Line 190: For Lu V the wavelength is suddenly changes from EUV to VUV range (all other isoelectronic sequences are measured in the EUV range).Please make a simple explanation.
Lines 228, 236 and 246: The spectra have been measured in the EUV range.However, ther e is no table such as Table 1.Please explain it.Response 1.It is clearly pointed out in Abstract that in the manuscript "The results obtained on the W VIII spectrum as well as on the isoelectronic spectra Lu V, Hf VI, Ta VII and Re IX in the VUV wavelength region are summarized with emphasis on the main trends along the isoelectronic sequence."Thereforewe give only short summaries for Hf VI, Ta VII and Re IX without the tables of wavelengths, energy levels and parameters.All these tables are in the original articles in Physica Scripta.From these spectra we present here only the isoelectronic trends of their parameters to support the reliability of our analysis of W VIII. 2. "Line 190: For Lu V the wavelength is suddenly changes from EUV to VUV range (all other isoelectronic sequences are measured in the EUV range).Please make a simple explanation." It is explained that we did not measured Lu V wavelengths, instead we used unpublished wavelength list from Ref.21 (lines 202-204)

"Line 301: It is not clear how the author could distinguish the ionization stage of tungsten ions in the spectra. What is the plasma condition? Please explain more details."
The distinguish of the ionization stage is performed by the observation of the line intensity changes with the variations of the spark plasma conditions by the changes of the voltage, inductance or capacitance in the range described in section "Experimental techniques".It is a standard procedure which hardly needed to be described in the article considered mostly as a summary.The measurements of the plasma parameters were out of the scope of our work.
All other suggestions are fully accepted with gratitude

Reviewer 3: Report and Author Response
This is an important contribution to the field of W spectroscopy in fusion applications.The paper is a review of contribution to an IAEA CRP on W spectroscopy, thus, per defintion mostly published results are presented and brought into context.
I suggest a couple of updates on the citations for the importance for ITER and fusi on in general (i.e. A. Loarte et al. on the ITER divertor).
Secondly, the authors refer only to ions as influx to the main plasma, but the sputtering provides neutral W. This neutral W has been used widely as influx measurements.I propose to include in t he introduction this type of influx measurements with appropriate references (e.g.L. Vainshtein et al, on WI spectroscopy) Thirdly, it would be of interest to see some information about the plasma conditions (ie.Te) in the two experiments used to obtain the experimental data.
Minor suggestions for corrections are added in the pdf as comments.
Overall very good work and almost ready for publication.
Response 1. "I suggest a couple of updates on the citations for the importance for ITER and fusion in general (i.e. A. Loarte et al. on the ITER divertor).Secondly, the authors refer only to ions as influx to the main plasma, but the sputtering provides neutral W. This neutral W has been used widely as influx measurements.I propose to include in the introduction this type of influx measurements with appropriate references (e.g.L. Vainshtein et al, on WI spectroscopy)" We did not intend to go into ITER plasma physics because we are not plasma physics experts.For us it is important just to mention that the W 7+ and W 8+ spectra are relevant to ITER divertor plasma.Therefore, we restrain from mentioning of possible presence of neutral tungsten in divertor plasma and from citation of numerous other articles dealing with the presence of tungsten ions in ITER plasma.2. "Thirdly, it would be of interest to see some information about the plasma conditions (ie.Te) in the two experiments used to obtain the experimental data." The measurements of the plasma parameters were out of the scope of our work.3. We do not accept suggested changes for the lines 69 and 76. 4. All other suggestions are fully accepted with gratitude.