Laser Ion Acceleration in a Near Critical Density Trap
Round 1
Reviewer 1 Report
Ales Necas, Toshiki Tajima, Gerard Mourou, and Karoly Osvay: Laser ion acceleration in a near critical density trap
The manuscript presents the idea of efficient proton acceleration in a specially shaped density trap, which is close or equal to the critical density in the pre-target plasma, where laser radiation is slowed down and trapped in order to achieve a highly efficient conversion of energy from laser radiation to protons. The presented theoretical results are very interesting and can contribute to the further development of laser proton sources. However, some changes would improve this work. Comments regarding some issues to be addressed before acceptance:
First, a laser is hardware that cannot be trapped in a density well. I recommend not using slang terms.
I further misunderstood the derivation of inequality (4). In retrospect, equality (5) requires that the velocity of the particle must be greater than zero: v>0. The derivation of (4) and (5) should be better worded. A similar problem occurs when we put the relationship (6) into the dispersion relation in accordance with how the authors explain this relationship. Because then we get that ω=ω, the commentary on dispersion should be better formulated.
Figure 6a-c shows the zoom into the domain in front of the tailoring region for 3 different times. However, Figure 7, which provides the most important result of this work, does not show the evolution of the proton distribution function, but only for the selected moment, which does not correlate with the moments presented in Figure 6.
The description of Figure 9 should be supplemented by the time to which the proton distribution relates.
From the experimental point of view the structure of the special tailored ionized hydrogen plasma is very fine. Its creation may not be successful due to insufficient contrast of existing lasers. It would therefore be appropriate for the authors to also discuss the value of minimum contrast.
Author Response
Dear Reviewer,
Thank you so much for your kind review of our manuscript. We appreciate your time and criticism and comments.
Please find our replies in the accompanying file.
With kind regards,
Ales
Author Response File: 
Author Response.docx
Reviewer 2 Report
The comments can be found in the uploaded file.
Comments for author File: 
Comments.pdf
Author Response
Dear Reviewer,
Thank you so much for your kind review of our manuscript. We appreciate your time and criticism and comments.
Please find our replies in the accompanying file.
With kind regards,
Ales
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The authors have addressed all comments and questions to my satisfaction. There are two minor changes I would suggest before publication:
1) Section 3, page 4, lines 132-133: I think the authors refer to Fig. 2a here and not Fig.1a as written in the text.
2) Section 3, page 5, lines 138-139:" .. we can see the longitudinal electric field (blue).. " In Fig. 2, the electric field is not visible, at least not for me.
Author Response
Thank you very much for your diligent reading of our manuscript.
1) Section 3, page 4, lines 132-133: I think the authors refer to Fig. 2a here and not Fig.1a as written in the text.
Yes, you are correct and we have modified inside the text.
2) Section 3, page 5, lines 138-139:" .. we can see the longitudinal electric field (blue).. " In Fig. 2, the electric field is not visible, at least not for me.
Thank you, yes the sentence is an error, we do not show the longitudinal electric field.
Author Response File: Author Response.docx
