Development of Cryogenic Systems for Astronomical Research

Round 1

Reviewer 1 Report

Comments for author File: Comments.pdf

Author Response

Pls., see attach

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper reports on some useful results and is a valuable summary of a great deal of work in building cryogenic systems. I would like to see it published, but I believe it requires major revision.

The paper presents itself as a review, which makes sense, since it covers a lot of related topics, in order to survey a subject. If it is a review, however, it should be structured as such. For a review, I would expect:
- far more references, so that the reader has immediate access to the literature on the subject
- a survey of work outside the authors' own, to give perspective
- a structure that clearly leads from general considerations to specific results
- a clear summary of the most important points
- clear definitions of technical terms when they first appear
None of these are really done here, so I don't agree with calling it a review. You could call it a summary, or a survey, but not a review.

The paper is too long for the results presented. It should probably be cut in length by at least 10%.

There are a number of places throughout the paper where mathematical terms are given in roman notation rather the more common italic lettering. Please go through all algebraic terms in the paper and ensure that they are in the correct type face.

It seems that much of the work reported in the paper was done in the context of the Millimetron space mission. I'm not familiar with this mission, and it would be helpful to summarise it and give a reference the first time it's mentioned.

The conclusions section, rather than simply stating what has been done (e.g. 'some transfer issues were considered') should give enough detail on the _results_ of the work that most readers will be able to simply use the conclusions, with the main body of the paper backing the conclusions up.

The whole paper should be carefully checked for spacing, punctuation etc. I've listed some of these below, but probably not all.

Specific notes:
l22 'photonics and electronics' - define these as optical and radio
l25 remove extra semicolon

l32 'deep cryogenic temperatures' - define
l34 'Used cryogenic systems' -> 'Cryogenic systems in use'
l36-37 'Deep ... nothing else.' This is a very vague statement. Of course, lower temperatures give lower thermal noise. What are you trying to say?
l 37-43 I don't see any reason to include this quotation.
l 46-47 I'm not familiar with the infinite round-trip interpretation. You should explain what this is, or remove it. It's not clear to me that the interpretation of temperature beyond using a K scale makes any difference to the results in the paper, so I would suggest removing it.

l60 'Mc. Magon' -> 'McMahon'
l62 delete 'in the book'
l69-70 'World leadership...' I don't think this assertion is correct. Many major new developments have nothing to do with space instrumentation. Either delete or clarify.
l77 'several dozen existing telescopes' - it's not quite clear what this means, but there aren't that many mm-wave and submm-wave telescopes. (Unless you count all ALMA antennas as separate telescopes.) You can't add several dozen telescopes.

l83 'awide' -> 'a wide'
l87 'own..' -> 'own.'

l115 the highest frequency end of the EM spectrum is gamma-ray, not X-ray
l122 The optical range does not require deep cryogenic cooling. The IR region, not mentioned here, generally requires more cooling than optical.
l125 You can't really call THz devices electronic (but not photonic), as you then state that they combine both approaches. I suggest removing this sentence.

Figure 1 appears to be reproduced from a book or similar. Please add relevant citation or credit for the figure.

Table 1 LN2 cooling is often used for eg radiation shields in colder systems.
Helium level cooling is generally used for SIS junctions.
Sub-K cooling is generally used for bolometers

l163 remove the (?)
l175 'deep cooling' define deep cooling and define the detectors - heterodyne or bolometer?
l179 'Such a setup...' this sentence does not contribute to the paper and should be removed

Section 2.3
I don't think this section is necessary. Since the paper is supposed to be a review of cryogenic applications, there is no need for a page about the theory of temperature. All the systems and applications mentioned can quite easily be understood in terms of a normal kelvin temperature scale, familiar to undergraduate students. I would recommend removing the entire section.

l276 'helium filler Dewars' -> 'helium filled Dewars'?
l280 what is the purpose of a nitrogen-free helium dewar? What advantage does it have?

l532 'the cooling object' - what does this mean? explain or change throughout
l534 'of the crucial significance' -> 'of crucial significance'
l539 'parries' -> 'carries'?

l543 delete 'on the contrary' - it's unnecessary
l553 'cold capacity' -> 'cooling capacity'?
l554 what is a 'cryoaccumulator'?
l555 'Refrigerators ... all heat flows' - I don't understand this sentence. Please rewrite.

l565 Voltage is usually expressed as V, not U

l585 what is 'vacuum density'?
l592 delete 'The fact is that'
l 597 and 600 what are the 'degrees' here? Kelvin?
l602 'coal' -> 'charcoal'?
l609 'based on getters' - please explain

l617 Figure 13 does not match the reference to it in this line.

l635 delete 'of cryostating systems'
l652 'life hacks of electrical interfaces' is not helpful. Perhaps 'general priciples of electrical interfaces'?

l666 'radiophysycal' -> 'radiophysical'
l671 'Cryostating' -> 'Cryostat' throughout
l676 delete 'with the possibility ... cryorefrigerator'

l704-5 why is the resolution of the microstep mode much higher (0.3mm) than the full-step mode (0.64mu)? 'practicallyachivable' -> 'practically achievable'

l732 'are occurred' -> 'occur'

l822 delete 'As you can see,'

l825 '10th floor, the cryogenic' -> '10th floor, where the cryogenic'

l908 delete 'using'

Section 4.1.3 - the biggest issue with vibration is generally microphonics, where the movement of the components leads to electrical signals. A great deal of work has been done on microphonics and their treatment, and this should be mentioned.

Figure 24 caption 'Petavatt' -> 'Petawatt'

l935 and 937 'passport' a better term would be 'specified', I think
l937 'mentioned above' - where exactly?

l956 why is a space mission simulator running at 4K? Space craft don't get that cold.

l975 'mirrors' -> 'mirror'
l982 'degrees' - does this mean K?

l1009 and following - there are several places where a dash - has been replaced by a division sign. Check and replace.

l1037 'thickness ~0.1 mkm' what is an mkm?

l1062 'CCD array' would probably be better than 'CCD matrix'
l1066 'The nitrogen level' -> 'Nitrogen level'
l1069 'a line of the developed various cooling systems of CCD matrices for' ->  'the lineage of CCD array cooling systems developed for'
l1070 'it is usable "soft" cooling' -> '"soft" cooling is usable'

l1135 MM -> mm throughout
l1144 delete 'formula 9'

l1166 the cos operator is usually written in roman type, not italic
l1181 'SBD' - please define
l1182 '10-13K, with the heating up to 10K' this is very unclear; please explain what you mean

l1188 'used to detection devices' -> 'used to cool detection devices'
l1203 'listened observatories' what does this mean?

Author Contributions - please check punctuation

Ref 47 'Cryojenics' -> 'Cryogenics'

Ref 55 Use small letters for the title

Ref 60 'Moden' -> 'Modern'

See above.

Author Response

Unfortunately, the reviewer joined the work when the second round had already been completed for the remaining reviewers. In this connection, a significant part of the comments have already been corrected.
Nevertheless, many significant comments were made and the authors thank the reviewer for his painstaking and high-quality work.

Author Response File: Author Response.pdf

Reviewer 3 Report

This manuscript provides an overview of different cryogenic astronomical instruments and cooling systems. Even though the authors are providing details on diverse instruments and cooling systems, overall the manuscript reads to me like a draft report. There are no clear systematic approaches and details on the design, assembly, integration, testing and validation of these instruments. There are a lot of details on various cooling systems, but in-depth analysis and originality are missing, which are critical for any peer-reviewed publication.  This could considered a review article, but still needs a significant improvement in presentation, structure and writing style. I am not sure all the figures are relevant here and the figures need appropriate referencing and captions should be self-explanatory. 

Need improvement in writing and presentation style, there is a lack of flow between sentences. Various grammar and typos needs to be corrected.

Author Response

Pls., see attach

Author Response File: Author Response.pdf

Reviewer 4 Report

The article “Cryogenic Systems for Astronomical Research in the Special Astrophysical Observatory of the Russian Academy of Sciences” provides an overview of the development of cryogenic systems operated at different temperature levels and the cooling principles for cooling microwave and optical receivers of various frequency ranges for astronomical research using the main instruments of the Special Astrophysical Observatory of the Russian Academy of Sciences, specifically the BTA optical telescope and the RATAN-600 radio telescope. Interesting and original results of the development of cryogenic technologies are presented, which in some cases can successfully compete with common alternatives for detectors in the corresponding wavelength ranges. I believe that the article complies with MDPI publication standards and will be of interest and useful to scientists and engineers in the field of developing receiving devices for astronomy. However, it requires significant improvement. Below are my comments.

Author Response

See the attach, pls

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

All my concerns are properly addressed. The revised manuscript can be accepted for publication.

Author Response

Thank you!

Reviewer 3 Report

Thank you, authors, for the response, however, I am still not convinced regarding my previous opinion- that the manuscript is still missing the originality and in-depth design/details.

Author Response

Dear reviewer,
We  agree with the fairness of a significant part of your comments. In the second round, we tried to improve the article as much as possible.
We worked on the first two sections, where the reviewer recommended improving the manuscript (introduction and references)
The reviewer was more pressing for improvements in subsequent sections.(research design,  described methods, presented resultes and conclusions). We also tried to improve them. However, we believe that we could not fully satisfy the reviewer. We present an updated version for his consideration.
And please note that following the recommendations of two of the four reviewers, we have formulated proposals to reduce a number of problematic sections. If this proposal satisfies the reviewer, then we confirm our readiness to remove the fragments highlighted in yellow.

Reviewer 4 Report

I don't have any more comments

Author Response

Thank you!

Round 3

Reviewer 3 Report

Yes, I would suggest  to remove the highlighted section in the current version of the manuscript. 

Check for the typos and grammatical errors.

Author Response

Dear reviewer,
Thanks for your comments and understanding!

We re-edited the English language. Corrections are visible highlighted in corrections mode.
We accept your proposal to remove unnecessary fragments. They are highlighted in yellow and we accept any number of the 6 highlighted fragments for removal according to the decision of the scientific editor.