MPI Parallelization of Numerical Simulations for Pulsed Vacuum Arc Plasma Plumes Based on a Hybrid DSMC/PIC Algorithm
Round 1
Reviewer 1 Report
The title is far from what it is discussed in the paper. There is a large part of the paper dedicated to the simulation and comparison with experiments (from p 8 to p 19) . In section 2 the authors describe a standard PIC/DSMC method and some criteria for parallelization. But no results are shown in terms on efficiency, CPU, ...So, I suggest to add a section dedicated to this analysis.
Author Response
We add another section named “Parallel efficiency Analysis” from page 19 to 21.In this section,we introduce two parameters about parallel efficiency and analyse the reseults of simulation based on the parameters.
Reviewer 2 Report
In this paper, the authors have developed a parallelized hybrid DSMC/PIC code. Since they described the details of the program structure and verified by comparing with the experimental measurements, I recommend the publication of this article after revision for the following points:
1. As I know, there have been many DSMC/PIC programs for plasma and/or ion plume analysis developed by other researchers. Can you add more references for that?
2. On page 2 (line 49), the authors stated that “In the vacuum arc expansion stage, the mainstream adopts the quasi-neutral hypothesis, ignores the influences of the sheath and secondary electron emission, and numerically simulates neutral particles and charged ions.” Can you add some reference for that to justify your assumptions?
3. Can you describe the details of the chemical reactions considered in your hybrid code in the revised manuscript?
4. Did you consider CEX in your simulations?
5. The resolution of Figure 2 is too low. Please include the higher-resolution figure in the revised manuscript.
6. On page 7 (line 14), “E” should be corrected as “e”.
7. On pages 7 (line 15) to 8, the authors stated that “In the plasma plume, if there is little difference between the number densities of neutral particles and charged ions, it will result in variations of several orders of magnitude between the average free path of neutral particles and the Debye length of the charged ions.” Can you add some reference for that to justify your statement?
8. Did you perform the axis-symmetric computation, or, 3-d computation? Please clarify that.
9. Please add the boundary conditions for electric potentials to Figure 4 in the revised manuscript.
10. How many simulated particles were used for the simulations?
11. Do you think that the length of 1 m downstream is enough to examine the phenomena?
12. On page 11 (line 1), “Z = 0 plane” should be corrected as “x = 0 plane”.
13. In Figure 9, the unit should be corrected as “m/s”.
14. On page 13 (line 19), the authors stated that “The atomic Ti velocity decreases after 120 us and the Ti2+ velocity decreases after 60 us, which fully shows that the ion velocity increases rapidly under the action of the electric field.” However, for t > 80, is there a possibility that the maximum velocity position is out of the simulation domain (Z > 1.5 m)?
15. In the verification simulation, how did you consider Ti, Ti2+, Ti3+, and Ti4+? Can you describe the details?
Author Response
Please see the attachment
Author Response File: 
Author Response.pdf
Round 2
Reviewer 1 Report
The corrections have been done as expected.
