Investigation of Power Transmission of a Helium Plasma Jet to Different Dielectric Targets Considering Operating Modes
Round 1
Reviewer 1 Report
I think there are too many keywords. And some of them are too general e.g. surface, helium.
Description of an experiment is not clear and should be improved. I suggest to move chapter 4 (description of the experiment and set-up) before chapter 2.
In chapter 2 there is a reference to Fig. 5 which appears at the end of the manuscript. I suggest to move figure 5 to chapter "Materials and Methods".
Fig. 5 - what is the distance dt?
The description of Fig. 1. is not clear.
Unify references - surname, initials
Unify references - abbreviation of the titles or no abbreviations.
Author Response
First of all, we would like to appreciate all the efforts and ideas we received from the three referees. We used the advice to further improve the quality and understanding of the manuscript by correcting mistakes, reformulating statements and advancing the interpretation. In the following, we would like to address the comments of each Referee individually. The text of the referees will be shown in italic, while our reply will be highlighted with bullet points in normal text format.
But before we dive into the individual comments, we would like to explain a major issue that came up with two reviewer reports. The first two reports propose to restructure the paper by moving the methods section in front of results and discussion. This is actually what we always prefer to do as well, but with the first form of contribution we tried to go with the guidelines of the journal by structuring accordingly to
Research manuscript sections: Introduction, Results, Discussion, Materials and Methods, Conclusions (optional).
Hence, this structure might have led to confusion. As a conclusion we received the permission to structure in the way proposed by the reviewers.
Now addressing the individual comments of the reviewers:
Reviewer #1
I think there are too many keywords. And some of them are too general e.g. surface, helium.
· We adjusted the keywords to be less general and yet follow the content of the work. Thank you for this advice to increase visibility of the contribution.
Description of an experiment is not clear and should be improved. I suggest to move chapter 4 (description of the experiment and set-up) before chapter 2.
· As described above, we are sorry for this inconvenience of the previous structure. The present contribution follows your proposal.
In chapter 2 there is a reference to Fig. 5 which appears at the end of the manuscript. I suggest to move figure 5 to chapter "Materials and Methods".
· As mentioned above, we adjusted the structure.
Fig. 5 - what is the distance dt?
· Actually the distance d_T (accidently written as d_t in the manuscript at some points) was varied in the master thesis which generates the basis of this work as well, but for this contribution we fixed the value to 6 mm. This was now updated and made clear all through the manuscript.
The description of Fig. 1. is not clear.
· We updated and specified the description of the figure(s).
Unify references - surname, initials & Unify references - abbreviation of the titles or no abbreviations.
· We corrected the formatting mistakes in the bibtex file and the references should now be in unified order
Reviewer 2 Report
General remarks:
The manuscript presents the results of a study of power transmission of a helium APPJ to different dielectric targets. The results, interpretation and overall science are definitely interesting and merit publication in this journal.
However, the manuscript is poorly organized, making it difficult to follow and understand. Material and Methods section must precede the Results and Discussion sections. Figure numbering and Reference list must be reordered accordingly.
If they stay in this form, Results and Discussion sections should be united in one section and subdivided into subsections.
Conclusions section should not contain any references.
All physical quantities must be listed after the equation or explained right before the equation.
Specific remarks:
Figure 1. red 4 misses ' (4'), caption: physical quantities in italics, dT instead od dt
Line 41: fig. 5, fig. 6 change in Fig 5. and Fig. 6
Lines 47 – Line 64 (1), (2), (3), (4) – it is not immediately clear that you speak about peaks in Figure 1, reorganize text or make subsections to be more comprehensive
Line 85 origin? Did you mean program Origin? In that case, please refer to the program correctly.
Lines 126-127: „The ratio represents how much power is dissipated outside in relation to inside depending solely on the dielectric permittivity“. outside, inside of what?
Lines 133-134: „It could very well be, that the setup operated in the low power mode.“ Please rephrase.
Figure 4. Miss-spelling: „plamsa“
Line 174: dT= 6 mm, since dT is constant you should indicate its value in the text.
Table 1. Relative permittivity; Polarization effect, there is no need for the third line *** in case of Tissue and E. coli.
Line 217 X.X.
Recommendation: Major Revision Required
Author Response
First of all, we would like to appreciate all the efforts and ideas we received from the three referees. We used the advice to further improve the quality and understanding of the manuscript by correcting mistakes, reformulating statements and advancing the interpretation. In the following, we would like to address the comments of each Referee individually. The text of the referees will be shown in italic, while our reply will be highlighted with bullet points in normal text format.
But before we dive into the individual comments, we would like to explain a major issue that came up with two reviewer reports. The first two reports propose to restructure the paper by moving the methods section in front of results and discussion. This is actually what we always prefer to do as well, but with the first form of contribution we tried to go with the guidelines of the journal by structuring accordingly to
Research manuscript sections: Introduction, Results, Discussion, Materials and Methods, Conclusions (optional).
Hence, this structure might have led to confusion. As a conclusion we received the permission to structure in the way proposed by the reviewers.
Now addressing the individual comments of the reviewers:
Reviewer #2
General remarks:
The manuscript presents the results of a study of power transmission of a helium APPJ to different dielectric targets. The results, interpretation and overall science are definitely interesting and merit publication in this journal.
However, the manuscript is poorly organized, making it difficult to follow and understand. Material and Methods section must precede the Results and Discussion sections. Figure numbering and Reference list must be reordered accordingly.
If they stay in this form, Results and Discussion sections should be united in one section and subdivided into subsections.
· We appreciate this motivating general remarks and we are glad to be able to move the methods section to the front to follow our preferred order as well.
Conclusions section should not contain any references.
· We removed the references from the conclusion section
All physical quantities must be listed after the equation or explained right before the equation.
· We added the missing quantity explanation and introduction of quantities to allow the reader to follow upon the thoughts involved. That you for this remark.
Specific remarks:
Figure 1. red 4 misses ' (4'), caption: physical quantities in italics, dT instead od dt
· The missing ‘ was added in the figure and the d_T was adjusted throughout the manuscript. Also we emphasized that d_T is not a variable by fixing the value in the setup figure.
Line 41: fig. 5, fig. 6 change in Fig 5. and Fig. 6
· The abbreviation of the figure references was adjusted to be consistent throughout the manusscript
Lines 47 – Line 64 (1), (2), (3), (4) – it is not immediately clear that you speak about peaks in Figure 1, reorganize text or make subsections to be more comprehensive
· The reference to the figure was adjusted by writing “#1 in fig. …”, the “#” was included to also distinguish towards the equations for the power measurement.
Line 85 origin? Did you mean program Origin? In that case, please refer to the program correctly.
· Indeed the program Origin was addressed as a common program in our daily data evaluation routine. We updated the reference by correct writing and naming the selling company OriginLab
Lines 126-127: „The ratio represents how much power is dissipated outside in relation to inside depending solely on the dielectric permittivity“. outside, inside of what?
· The sentence was made clear to address the locations of power dissipations, namely inside the capillary between the two ring electrodes and outside between the capillary edge towards the target.
Lines 133-134: „It could very well be, that the setup operated in the low power mode.“ Please rephrase.
· The sentence was rephrased and the relation to the literature updated to state in a clear way the intended message. The previous version was unclear and hence revised.
Figure 4. Miss-spelling: „plamsa“
· The respective figure was updated and the misspelling updated.
Line 174: dT= 6 mm, since dT is constant you should indicate its value in the text.
· As mentioned above, this was changed and mentioned clearly throughout the manuscript
Table 1. Relative permittivity; Polarization effect, there is no need for the third line *** in case of Tissue and E. coli.
· The third line “***” was removed.
Line 217 X.X.
· The remaining X.X. was the task of the review process, which was performed now and hence we updated the names in charge of the review process. Thank you for the reminder.
Recommendation: Major Revision Required
Reviewer 3 Report
This manuscript reports the interaction of an atmospheric pressure plasma jet with different dielectric surfaces. The authors measured the dissipated powers inside the jet (P1) and between the jet and the surface (P2) and found the transition between two different operation modes, low power mode and high power mode. The authors also show that the power ratio of P2 to P1 increases with increasing permittivity of the dielectric surface, but the plasma power (P_plasma) is constant. These phenomena are interesting, however, the results on the mode change to the high power mode (the plasma touching the dielectric surface) and power dissipation change by changing the material of counter electrode (Eur. Phys. J. D, 68, 56 (2014), Spectrochim. Acta B, 103, 124 (2015), and so on) have been reported. Furthermore, in this manuscript, there is few discussion on the mechanism of the dissipated power transition depending on the dielectric materials. Therefore, I cannot understand the original points of this manuscript. In addition, since there is no result on plasma parameters and/or reactive species in front of the dielectric surface, it is not clear how the power dissipation near the dielectric surface contributes the plasma medical application.
The authors should make clear the detailed mechanism of the dissipated power transition depending on the dielectric materials and the resultant plasma parameter and/or reactive species in front of the dielectric surface.
Detailed comments are as follows.
1. The authors mentioned that P1 starts to decrease and P2 increases from Uapp = 2 kW and the phase transition occurs above 2 kV independent of the dielectric materials. Why the discharge transition occurs at the almost same Uapp (= 2 kW) nevertheless the dielectric materials are different?
2. The authors also mentioned that P1 rises again up to 4 kV and show the second drop in the same way except for TiO2. However, the minimum P1 seems to appear at the different Uapp which increases with an increase in the permittivity. Also Uapp yielding the maximum P1 before the second drop seems to increase with the permittivity. The authors should explain these phenomena to understand the mechanism of change in the power dissipation ratio of P2 to P1.
3. The authors mentioned that P_plasma remains roughly constant for the different dielectric materials. If the permittivity of the electrode is different, the equivalent circuit constant is changed, which could cause the change in the dissipation power. Why P_plasma is almost constant?
4. It is not clear the definition of effluent power P_effluent. The authors mention that P_effluent is the loss into emission and species production, but I think P1 and P2 are also the loss into emission and species production inside the jet and at the dielectric surface by the production of the plasma.
5. The authors should show the results of the reactive species in front of the dielectric surface depending on the dielectric materials, which are very useful for the readers who want to control the kinds and amount of the reactive species for medical applications.
Author Response
First of all, we would like to appreciate all the efforts and ideas we received from the three referees. We used the advice to further improve the quality and understanding of the manuscript by correcting mistakes, reformulating statements and advancing the interpretation. In the following, we would like to address the comments of each Referee individually. The text of the referees will be shown in italic, while our reply will be highlighted with bullet points in normal text format.
But before we dive into the individual comments, we would like to explain a major issue that came up with two reviewer reports. The first two reports propose to restructure the paper by moving the methods section in front of results and discussion. This is actually what we always prefer to do as well, but with the first form of contribution we tried to go with the guidelines of the journal by structuring accordingly to
Research manuscript sections: Introduction, Results, Discussion, Materials and Methods, Conclusions (optional).
Hence, this structure might have led to confusion. As a conclusion we received the permission to structure in the way proposed by the reviewers.
Now addressing the individual comments of the reviewers:
Reviewer #3
This manuscript reports the interaction of an atmospheric pressure plasma jet with different dielectric surfaces. The authors measured the dissipated powers inside the jet (P1) and between the jet and the surface (P2) and found the transition between two different operation modes, low power mode and high power mode. The authors also show that the power ratio of P2 to P1 increases with increasing permittivity of the dielectric surface, but the plasma power (P_plasma) is constant. These phenomena are interesting, however, the results on the mode change to the high power mode (the plasma touching the dielectric surface) and power dissipation change by changing the material of counter electrode (Eur. Phys. J. D, 68, 56 (2014), Spectrochim. Acta B, 103, 124 (2015), and so on) have been reported. Furthermore, in this manuscript, there is few discussion on the mechanism of the dissipated power transition depending on the dielectric materials. Therefore, I cannot understand the original points of this manuscript. In addition, since there is no result on plasma parameters and/or reactive species in front of the dielectric surface, it is not clear how the power dissipation near the dielectric surface contributes the plasma medical application.
The authors should make clear the detailed mechanism of the dissipated power transition depending on the dielectric materials and the resultant plasma parameter and/or reactive species in front of the dielectric surface.
· Indeed first research on a small selection of dielectric targets was previously presented and discussed with regard to different aspects. Yet however, we find that a well structured investigation with a clear set of dielectric parameters was and is still missing. The selection of dielectric surfaces hardly covers a wide range of relative permittivity. Also most investigations miss the invasive nature of surface placement in front of the device, resulting in mode changes. Hence the joint presentation and characterization of the mode change together with the change of dielectric permittivity in a thereby controlled setting is clearly not part of the referred literature. We therefore believe to contribute an original point to the few papers addressing plasma discharge – target property interactions.
· The relation of the observed power changes with plasma parameters is clearly an interesting question and we would like to answer this point more clearly and would like to take up this impulse to advance the contribution further.
Detailed comments are as follows.
1. The authors mentioned that P1 starts to decrease and P2 increases from Uapp = 2 kW and the phase transition occurs above 2 kV independent of the dielectric materials. Why the discharge transition occurs at the almost same Uapp (= 2 kW) nevertheless the dielectric materials are different?
· The ignition up to 2 kV is determined purely by the geometry of the initial plasma device, namely here the capillary with two ring electrodes. By applying the voltage, the electrical field distribution is determined. Up to 2 kV, the discharge operates similar to a free jet setup without a target, yet the discharge stays within the capillary. Once the electrical field is high enough, the discharge leaves the setup and also touches the target. Once this mode comes into play, the properties of the target effect the discharge actively.
2. The authors also mentioned that P1 rises again up to 4 kV and show the second drop in the same way except for TiO2. However, the minimum P1 seems to appear at the different Uapp which increases with an increase in the permittivity. Also Uapp yielding the maximum P1 before the second drop seems to increase with the permittivity. The authors should explain these phenomena to understand the mechanism of change in the power dissipation ratio of P2 to P1.
· First for TiO2. While the presented measurements do not show the drop for TiO2, it can be observed for an even higher applied voltage. The scale just didn’t include this event. For higher voltages, the stability was partly lost due to parasitic discharges in the gap.
· Thank you also for pointing out the included observation of the second discharge occurring for higher relative permittivity values. We added the explanation to address this observation:
“One further observation is the increase of U_app required for the second strong increase when increasing the dielectric permittivity.
A surface with a lower permittivity resembles a lower capacity and is charged within a shorter time frame compared to higher \epsilon_r. Once charged until a certain point, the local electrical field of the surface charges generate a counteracting electrical field negating the external electrical field from the setup. By further increasing the applied voltage U_app, the external field is increased again until a further ignition is enabled considering memory effects and hence reduced ignition requirements (see #3 and #3' in fig.~\ref{fig2}). For higher \epsilon_r a higher capacity has to be charged and the additional charges are distributed through surface ionization waves (SIWs)~\cite{Norberg2015b}. As a result of the longer charging time and increased spatial distribution through SIWs the countering of the external electrical field requires a longer time frame and ultimately a higher U_app for the second discharge signal.”
3. The authors mentioned that P_plasma remains roughly constant for the different dielectric materials. If the permittivity of the electrode is different, the equivalent circuit constant is changed, which could cause the change in the dissipation power. Why P_plasma is almost constant?
· The first thing to comment is actually your remark #1. While the dielectric of the target is changed, the intentional first ignition inside the capillary is not changed at all, only the “aftermath” of the discharge and how it is distributed. From our perspective this might be the only thing that stays constant when changing the surface electrode. We previously published about an assumption of a geometrical limitation of power consumption. Combining this with the present limitation value of PPlasma = 200 mW for 2 kV and 600 mW for 3.5 kV, maybe the applied voltage enhances this geometrical limitation by increased electrical fields and a hence increase volume to ignite the plasma in and a consecutive increased power dissipation volume. From this volume, only parts of the power is then dissipated at either P1, P2 or the open space in between the three electrodes. The later interpretation describes our “P_Effluent”. Since we are still on the search of a way to grasp the meaning and interpretation of P_Effluent and the separation of power dissipation, we don’t quite go to deep into these thoughts inside the paper and hope this explanation can contribute to your understanding.
4. It is not clear the definition of effluent power P_effluent. The authors mention that P_effluent is the loss into emission and species production, but I think P1 and P2 are also the loss into emission and species production inside the jet and at the dielectric surface by the production of the plasma.
· In our interpretation, P1 and P2 are the power dissipation at the dielectric surface. For the DBDs, this power evaluation is assumed to correspond with our interpretation of PPlasma. However, in these plasma jet configurations, the discrepancy between P1, P2 and PPlasma leads us to believe, that there is a loss channel to dissipate energy in between the power input PIn and the dissipation at the two electrodes P1 and P2. Hence one way the “lose” energy would be in emission and species generation (e.g. also metastables). We added a description of P1 und P2 in the methods part to address this issue.
5. The authors should show the results of the reactive species in front of the dielectric surface depending on the dielectric materials, which are very useful for the readers who want to control the kinds and amount of the reactive species for medical applications.
· We agree that these results will be useful for the readers and have hence used the chance of the review process to perform a first investigation with FTIR measurements of the far field species densities. The results are now implemented throughout the paper and show a weak, yet clear increase of ozone density from 1*1013 cm-3 up to 4*1013 cm-3.
Round 2
Reviewer 2 Report
The authors accepted the reviewers’ recommendations and have corrected the manuscript accordingly.
Reviewer 3 Report
Since the authors have addressed all my comments, the revised paper is acceptable.
