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Published 20 hours ago • verified publisher icon ECP-WarpX

[WIP] Option for antenna with non-zero velocity

Open MaxThevenet opened this issue 3 years ago • 6 comments

The laser antenna can already move, and this is used when running in the boosted frame. However, the option to set separately the velocity of the antenna was not implemented. This is what this PR proposes. For the moment, the antenna can only move in the z direction, which should cover most use cases.

MaxThevenet avatar Feb 07 '22 11:02 MaxThevenet

Wow, thanks, I need to practice more. If that's fine with you, I'll just simplify the option and only have 1 input parameter vz_antenna, which should avoid confusion.

MaxThevenet avatar Feb 08 '22 16:02 MaxThevenet

HIP warning/error addressed in #2840

ax3l avatar Feb 10 '22 19:02 ax3l

Thanks for this PR @MaxThevenet.

I have 2 quick additional suggestions (I can implement them in this PR, if you agree with them):

  • Would it be OK to modify the code and documentation so that antenna velocity v_antenna is considered to be along the normal to the emission plane (instead of z specifically)? (This would make the code slightly more general and allow moving antennas in arbitrary directions - as long as the laser is emitted in the same direction.)
  • Would it be OK to consider that a non-zero v_antenna is incompatible with the boosted-frame? This is also what we do in FBPIC for instance, because I did not generalize the formulas to make it compatible with both non-zero v_antenna and boosted-frame simultaneously. (See also the previous commit - which I think fixed some of the automated tests - and the associated review comment.)

RemiLehe avatar Mar 10 '22 15:03 RemiLehe

Regarding the first point, note that the assumption that the velocity is along the normal to the plane is actually made implicitly here, I think: https://github.com/ECP-WarpX/WarpX/pull/2832/files#diff-b9f19654f5fb894bff1eed74a6a13ebc5eb34244edbef306ac5d169743215883R597

RemiLehe avatar Mar 10 '22 15:03 RemiLehe

I added an automated test that emits a laser with the moving antenna. (The laser is emitted in the direction opposite to that of the antenna motion.) movie

RemiLehe avatar Mar 14 '22 20:03 RemiLehe

Some action items left:

  • [ ] Need to fix the automated tests
  • [ ] When using the moving antenna, I noticed that the time of profile_t_peak needs to be adapted in a non-intuitive manner. This needs to be fixed.

RemiLehe avatar Mar 21 '22 17:03 RemiLehe