Rebuttal from authors: 36217B
Dear Editor,
We have recently received the third set of comments by the referee on the manuscript POP36217B. Unfortunately, we strongly believe they would do damage the paper if implemented. In particular, one comment, in the form of a demand, is provably incorrect.
First, we remind the editor that, in response to the first review, we made numerous and significant changes to the original manuscript
(including suggestions from DIII-D scientists based on feedback from two in-house presentations). The significantly revised manuscript was favorably received through poster and oral presentations in the USA and
Europe. It refined and strengthened the results presented in the original manuscript. Subsequently, the referee's second review of the
(revised) manuscript included a lengthy list of new criticisms, many of which we disagreed with. Some criticisms we disagreed with rather strongly. Nevertheless, we did our best to incorporate whatever we found to be constructive. Now, we have been presented with the referee's third review and can no longer abide his demands. In particular, he says he (demand B) will accept the manuscript IF and ONLY
IF we "address the newly uncovered issue that the beam species is not correct". This claim and associated demand are both completely erroneous; the beam species used in the transport analyses are all correct (we have made repeated checks of this, and have in fact redone the analysis in question using both TRANSP and ONETWO, which we believe goes above and beyond the call of duty). We find the other demands by the referee (A,C-F) to be either unacceptable or unnecessary (please find our corresponding comments below).
At this point we must ask for either an adjudication, or that the journal publish the article (which has been refined through numerous reviews and presentations) as-is.
Sincerely,
The Authors
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Comments on the Referee's points A,C-F:
A. Delete the sentences requested to be deleted in 2.1 and 2.5, finding substitutes that are closely related to, and supported by the contents of their paper.
["In particular, the experimentally observed favorable scaling of confinement time with isotope mass remains an unresolved problem." 2.1)
I recommend deleting the sentence, "In particular...".
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"Ultimately, a commonly accepted and robust theoretical explanation of the isotope effect which is consistent with the other experimentally established parameter scalings is lacking." 2.5) Delete the sentence
"Ultimately..."]
- These sentences are carefully worded and accurate, and serve important purpose. Deleting them would damage the paper.
C. Insert a sentence in the abstract before "The presence of any non-trace..." to the effect of, "However, these effects are still not sufficient to explain isotopic mass scaling in experiments, with gradients held fixed."
- We mention this two times in the paper. In page 12: "This is a strong favorable deviation from pure gyro-Bohm scaling which predicts
$1/\sqrt{2}$ times lower transport in the hydrogen plasma, however it is still weak to explain the experimentally observed favorable mass scaling in itself." and also in the Conclusions section: "However, this deviation in the hydrogen case is still not sufficient to explain any strong favorable mass scaling of the global energy confinement time."
D. Add Ref. [4] together with Ref. [3] on page 2.
- The range of mass scaling we mention in the last sentence of the second paragraph in page 2 can be found in Ref. [3] and not in Ref. [4].
In particular, Ref. [4] does not mention mass scaling of the confinement time close to ~A^0. However, in the preceding sentence (where it is adequate) we refer to both [3] and [4].
E. Ref. [11] is mentioned incorrectly on page 3. Ref. [11] does not contain such a statement, and because all simulations in that paper were local, without sheared flows, the result is necessarily gyroBohm.
- We write: "In local nonlinear gyrokinetic simulations for the ITG dominated collisionless GA standard case [10] Estrada-Mila et al. found practically no deviation from gyro-Bohm scaling [11] for D, T and DT plasmas."
The corresponding statement in Ref. [11]:
"This means that if one simulates a pure-D plasma with adiabatic electrons and obtains $\chi_D=C \chi_{GBD}$, then the transport in other pure plasmas can be obtained by scaling arguments alone: $\chi =
\sqrt{A/2} C \chi_{GBD}$, where A is the isotope atomic mass. ...
Looking at the pure D, DT fictitious species, and T energy diffusivities
$\chi$, we see that the ratios (1, 1.08, 1.21) deviate little from the expected $\sqrt{A/2}$ ratios."
F. Move the equation (2) to the Appendix.
- We find this demand unnecessary. The purpose of this equation is to show that the linearized collisionless gyrokinetic equation depends on
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charge and mass through c_s and \rho_s, which is important for the reasoning that follows the equation.
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