Proposal of a New Double-Nozzle Technique for In-Gas-Jet Laser Resonance Ionization Spectroscopy
Round 1
Reviewer 1 Report
The work by V. Varentsova is devoted to the application of the conjugate simulation approach for analyzing rarefied gas dynamics during gas ejection through nozzles of various geometries. Essentially, the article is divided into two parts. The first part models the diffusive motion of 164Dy atoms in an inert gas flow exiting through a nozzle installed on the experimental JetRis setup. The second part considers a double nozzle. Based on the conducted simulations, it is demonstrated that gas delivery for atom research can be improved.
The work has a number of important comments and questions:
1. The presented materials are very inconvenient to perceive. In particular, complete schematics of the calculation domains are not presented, which makes it difficult to understand the task. For example, the first part of the work assumes a calculation related to the experimental setup presented in work 33 (which, by the way, has an incorrect DOI listed). It would be appropriate to include a nozzle diagram in this work. A similar comment is appropriate, albeit to a lesser extent, for the second part of the work. Figures 12 and 13 differ slightly in geometry.
2. The work performs a multifaceted analysis of substance flow for a known gas source. However, there is no direct comparison, even by indirect parameters, between the experiment and the calculation, although experimental data for such a comparison are available in the references throughout the text.
3. The labels on different figures for "Longitudinal velocity spread" are in different units, including mm, which is surprising. Throughout the text, carelessness in presenting the results can be observed, which worsens the perception of the work. The label for Figure 14 is incorrect. However, it is worth noting that the article is written in excellent English and the sentences are formulated very accessibly.
4. In its current form, the work is aimed at calculating a specific setup, which probably significantly reduces its value for external readers. However, the proposed approach with the use of a double nozzle could be attractive for many experimental setups with gas delivery. For example, in the creation of cluster beams.
[1] K.A. Dubrovin, A.E. Zarvin, V.V. Kalyada, A.S. Yaskin, Influence of the outflow initial parameters on the transverse dimensions of underxpanded argon jets in presence of condensation, Vacuum. 207 (2023) 111651. doi:10.1016/j.vacuum.2022.111651.
[2] S. V. Starinskiy, A.I. Safonov, Y.G. Shukhov, V.S. Sulyeva, I. V. Korolkov, V.A. Volodin, L.S. Kibis, A. V. Bulgakov, Nanostructured silver substrates produced by cluster-assisted gas jet deposition for surface-enhanced Raman spectroscopy, Vacuum. 199 (2022) 110929. doi:10.1016/j.vacuum.2022.110929.
5. Figure 4 is very difficult to read, especially the numerical labels. It is very surprising to accelerate the flow in the calculation to 5 km/s (although the subsequent velocity on the figures is an order of magnitude less - it is worth understanding this contradiction). How accurate are the specified values? It is also surprising how much the flow core is cooled below 20 K down to 3 K (Figure 4). Are the calculation results conservative? Under such conditions, one could expect the condensation of the inert gas and the formation of clusters, which will undoubtedly affect the dynamics of the particle spreading and diffusion under investigation. However, there are no comments on the cluster phase in the text.
Author Response
Dear Reviewer,
many thanks for your work on revising my manuscript.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The manuscript of Victor Varentsov reports a comprehensive, quantitative simulations-based study on atomic beam extraction from a gas cell followed by the characterization of supersonic expansion through a nozzle. The simulations are performed in two steps; a) gas dynamics parameters are obtained for the gas cell and post-nozzle expansion and b) obtained parameters are utilized as input parameters for Monte Carlo simulations in order to extract trajectories for 164Dy and 253No atomic beams. The parameters corresponding to nozzle design, in the first part of the manuscript, are carefully selected to complement ongoing and future experiments at GSI. In the later part of the manuscript, author proposes a double-nozzle design. The double-nozzle design not only exhibits enhanced diffusion efficiency in comparison to GSI nozzle due to gas vortex formation leading to reduced interactions between atoms and the nozzle wall, the beam quality remains robust for a significant variation in the pumping speeds. Finally, author proposes the extension of double-nozzle design to existing and future experimental setups for improved atom/ion spectroscopy. It would be interesting to see a comparison with the experimental data in future.
For Fig. 7 (page 7), the longitudinal velocity distribution is narrower for 30 mm data in comparison to 50 mm separation from the nozzle. In contrast, the radial velocity distribution appears sharper for the 50 mm separation in Fig. 8 on the same page. Can author explain why would that be the case?
Moreover, following are the minor corrections I would recommend:
1. There is a repetition of the sentence “But here we ……. Authors of [32]” from line 132- 135.
2. Lead Iodine atomic and molecular beam descriptions as PbJ and PbJ2 should be corrected to PbI and PbI2 from line 262 to line 263.
In conclusion, I find this manuscript detailed and certainly suitable for the publication in atoms.
Author Response
Dear Reviewer,
many thanks for your work on revising my manuscript.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The author's responses are quite convincing. However, I still believe that the scope of the problem addressed is rather narrow and may not attract significant interest from the general public. Nevertheless, if there are specialists interested in this topic, they will obtain very valuable material for study. Accordingly, I believe that the material can be published in its current form.
There are just a few short comments to consider:
1. The caption for Figure 14 refers to Figure 10 as "double-nozzle design that shown in Figure 10," although Figure 10 displays results of Monte Carlo simulations.
2. I still recommend increasing the resolution in the legends for Figure 4 and similar figures. Due to poor resolution, I saw 5443 m/s instead of 544.3 m/s.
Author Response
Dear Reviewer,
Thank you very much for your work in carefully reviewing my manuscript for the second time and for your generally positive evaluation.
With best wishes,
Victor Varentsov
