Fix nbi power: correct shine-through, use plasma-coupled power instead of raw power; corrected wall-plug power conversion

[grmtrkngtn]

Description

• We were applying f_p_beam_shine_through incorrectly in two ways:
  • f_p_beam_shine_through represents the fraction of beam power that is not absorbed, but we were using (1 - f_p_beam_shine_through)
  • the fraction was only being applied to part of the power term due to operator precedence, rather than the total beam power
• Fixed ion/electron power split:
  • previously based on injected beam power
  • now correctly based on plasma-coupled beam power
• Fixed wall-plug power calculation (pwpnb):
  • previously only part of the power term was divided by injector efficiency
  • now the full beam power term is divided by efficiency

Checklist

I confirm that I have completed the following checks:

• My changes follow the PROCESS style guide
• I have justified any large differences in the regression tests caused by this pull request in the comments.
• I have added new tests where appropriate for the changes I have made.
• If I have had to change any existing unit or integration tests, I have justified this change in the pull request comments.
• If I have made documentation changes, I have checked they render correctly.
• I have added documentation for my change, if appropriate.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 52.07%. Comparing base (4c99916) to head (9c9ea34).

Files with missing lines	Patch %	Lines
process/models/physics/physics.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4187      +/-   ##
==========================================
- Coverage   52.07%   52.07%   -0.01%     
==========================================
  Files         148      148              
  Lines       30321    30319       -2     
==========================================
- Hits        15791    15789       -2     
  Misses      14530    14530              

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[kj5248]

Looked through it and I think the changes to how we use f_p_beam_shine_through is definitely correct as is switching to using the deposited beam power for the ion/electron power split calculation. Good catch with the wall-plug power calculation someone definitely stuck the brackets in the wrong place. If you double check the sigbeam function and probably just change the function description and push that I will approve it.

[je-cook]

I'll merge once the conflicts are fixed