Overview and Commissioning Status of the UCLA MITHRA Facility

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors give a comprehensive status report of the MITHRA facility at UCLA.  The progress reported is significant and of interest to the community.  While I think the paper is suitable for publication, I have a few minor suggestions that I think will improve the clarity of a few points.

I was wondering if the authors expect the velocity compression in the gun to be close to ideal, or if they anticipate the beam to have significant residual energy chirp out of the gun.  Perhaps the authors could include such clarification in the paragraph from lines 88-98.  If they expect a chirp, then they should also add whether the energy spreads included in Table 1 is projected or slice.

line 146 contains "the the"

line 153: I find the statement "the resultant energy spread can be indicative of the bunching potential" to be a bit unclear.  Are the authors stating that the measured energy spread can indicate the potential for bunching?  Also, it would be nice if the authors supplied a number to the energy spread measured in Fig. 4, even if this is a preliminary finding.  Finally, the authors should clarify if the numbers in Table 2 are measured or expected.

 

Author Response

1. There is no residual chirp as it is washed out during compression.  I have addressed and included this in the paper.
2. Fixed
3. Yes and the figure has been updated to show the energy scale.

Reviewer 2 Report

Comments and Suggestions for Authors

See attached.

 

Comments for author File: Comments.pdf

Author Response

All comments have been addressed and included in the paper.

1. The parameter table was generated using GPT and was specific for low energy spread while still optimizing compression and emittance.  Other applications (e.g. space plasma) have different needs, like shorter bunch length, with GPT also being used to optimize this, adjusting parameters like injection phase.  Additions have been made to the paper to show this.
2. Simulations showing evolution of the beam have been added.
3. A paragraph on the motivation and expected measurements to be made at LAPD and for space plasmas has been included.  
4. Jovian electron spectrum has been included.
5. THz and beam parameters have been included.
6. Parameters have been included.  Beam rep rate can be increased to 10 Hz as needed for application experiments.
7. EOS and a delay line will be used for synchronizing at the IP.
8. Compressor will eventually operate in vacuum once transport line is built.  Commissioning has been done in air.
9. Getting to 1-2 ps from 35 fs was important due to space charge.  We have different lengths of dispersive glass we can use to explore optimization of beam parameters.  It may be necessary to eventually build a grating or prism stretcher, but at the moment, fine control of the laser pulse length is not critical to operation.
10. Following laser cleaning methods at ASTA, we don't expect an increase in dark current.
11. Energy scale has been included.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The edits look good.

Reviewer 2 Report

Comments and Suggestions for Authors

Following the authors' revisions, the paper has shown significant enhancement in both clarity and scientific content. In my view, it is now suitable for publication without any additional modifications.