A Realistic Spark-Gap Model in Computer Simulation of Blumlein Transmission Line

Round 1

Reviewer 1 Report

In this paper, the authors have proposed a numerical model of a spark-gap which can be integrated with a full-wave simulation and claimed that it could simulate many high voltage devices in the circuit model. The paper has a merit in its originality and novelty of the proposed model, however, the validations of the model was not performed on many devices as claimed and the results were not presented in a way that shows the agreements between the experimental and numerical model results. Therefore, if the authors could address the points raised as stated below, it would be reasonable to recommend this paper for publication in this journal.

1. The authors should elaborate more on the advantages and novelty of the proposed model in the Introduction section.
2. In the Results section, the comparisons of results between the experiments and numerical model need to be presented clearly in graphs showing the good agreements between the two of them.
3. In the Discussion section line 322, the sentence “many high voltage devices” have to be changed as this paper only performs two experiments.

Author Response

Thank you for your comments. It is true, that we have tested our spark-gap model only on two devices.

Below we will address the main points from the review:

1. The authors should elaborate more on the advantages and novelty of the proposed model in the Introduction section.

This is a very good point, and we have reworked the introduction accordingly.

2. In the Results section, the comparisons of results between the experiments and numerical model need to be presented clearly in graphs showing the good agreements between the two of them.

Our paper is aimed at testing if our approach is a viable alternative to modeling with a time-varying resistor approach. We plan to compare the results with measurements of a real Blumlein Transmission Line in the future. 

However, in the revised version of the paper we couldn't find a include graphs as they easily become cluttered. On the other hand, we have improved the text of the Results section aid in comparison between the circuit models.

3. In the Discussion section line 322, the sentence “many high voltage devices” have to be changed as this paper only performs two experiments.

Indeed, in the revised version of our paper we have clearly stated that two experiments have been carried out.

Reviewer 2 Report

• Abstract is somehow dry and author need to present a result.

• Introduction: Problem statement is not clear. The novelty of the job need to be bold. The objective of this work need to be clearly stated in last paragraph of introduction.

• First paragraph should be general statement of research topic. 
• Results section have only one paragraph. more explanation should be added.
• Authors wrote this manuscript as a report not as research article. Research articles have defined structure. Please follow it.
• How important is antenna in terms of input impedance matching?
• What are the limitations of presented study?

Author Response

We are grateful for your comments. We have used them to improve our paper.

Below we provided a detailed answers to the main points of your review:

• Abstract is somehow dry and author need to present a result.

This is true, and we have rewrote that part of our paper to better reflect the results of our research.

• Introduction: Problem statement is not clear. The novelty of the job need to be bold. The objective of this work need to be clearly stated in last paragraph of introduction.

We had reworked the introduction. The problem statement has been reformulated, and we have clearly stated that (to the best of our knowledge) such a coupling of circuit-field model of a Blumlein Transmission Line has not been presented before. We had added the objective of our research in the end of the introduction.

• First paragraph should be general statement of research topic. 

  The first paragraph has been adjusted.

• Results section have only one paragraph. more explanation should be added.

Thank you, the section is indeed very short as a preliminary comments on the results were presented in Section 4: Experiments. Now, Section 5: Results expands on the output of the simulations and summarizes it highlighting features of the proposed model.

• Authors wrote this manuscript as a report not as research article. Research articles have defined structure. Please follow it.

That is an especially valuable comment, thank you.  More emphasis has been placed on analysis than merely describing the process of building the computer model.

• How important is antenna in terms of input impedance matching?

This point needs more explanation as it depends on a few factors.

Firstly, if we want to design a real pulse radiating system (Blumlein Transmission Line feeding an Impulse Radiating Antenna), then matching the input impedance of the antenna and the characteristic impedance of the BTL is crucial. The antenna had to be also designed for the frequency spectrum of the propagating high voltage pulse.

Secondly, we should be concerned with both the input impedance of our antenna and the characteristic impedance of the BTL. For that, a more detailed model of the geometry will be crucial. Our field model is defined in 2D Cartesian coordinate system, so we cannot simulate a coaxial BTL nor a parallel plate BTL (as we neglect the fringing field near the edges).

Our numerical experiments were designed for confirming that we can observe the main characteristics of the interaction between BTL (and it's spark-gap) and the load (e.g. an antenna). However, the antenna parameters was not optimal as that was not the goal of the experiment. We have reworked that part of the paper to make our intentions more clear.

• What are the limitations of presented study?

This is an important question and a valuable comment. The proposed computer model still works on few assumptions:

1. that we know the parameters of the spark-gap: the gas pressure, the inductance and capacitance of the electrodes and connected wiring;
2. that the spark-gap can be represented as a circuit of lumped elements, i.e. electromagnetic waves within the spark-gap are not represented;
3. the field simulation works in 2D Cartesian coordinate system: so for now we can only model transmission lines of an infinite width (in z-direction), no axial symmetry or 3D electromagnetic fields are yet modeled;
4. the relative permittivity and permeability have to be time-invariant and uniform over the computational domain.

The above list has been missing in the first version of the paper. We have added it in the revised version. Thank you for pointing that out.

Reviewer 3 Report

The manuscript "A Realistic Spark-Gap Model in Computer Simulation of Blumlein Transmission Line", by Bartosz Chaber and Wiktor Łodyga, highlights results of computer-based simulations regarding spark gap model of blumlein transmission line. The manuscript is very well- prepared, the information is clear presented, the graphs along diagrams and equations, are inserted and explained accurately, being easy to be read by the audience. The manuscript can be published in current form.

Author Response

Thank you for your kind comments on our paper.

Round 2

Reviewer 2 Report

Revised manuscript can be accepted for publication.