The E coils and F coils do not use same unit

[AreWeDreaming]

The E and F coils are combined when loading from the EFIT tree. However, the F coils have the turns multiplied with the current, which one could argue is an preexisting error in MDS+. This would be at least consistently wrong but the F-coils are combined with the E-coils in pf_current in constraints which are stored correctly. Following options:

• Merge this and remove the mapping completely
• Try to fix the mapping, but this is tricky because the information on how many windings each coil has is not MDS+. For DIII-D there is some expectation that the F-coils always have the same amount of turns for all shots, but the EFIT tree and mapping is not DIII-D specific, so it gets complicated very quickly.
• Leave it because it is consistent how the code wants its pf_currents. Here it is important to remember that this is the mapping for EFIT not the mapping for pf_active. I leave it to @smithsp to make an executive decision and @bechtt to add his own opinion.

[torrinba]

The second option would be the best in my opinion. The MDS+ organization used by different machines (if they even do) is not universal, so I would consider most of the EFIT mapping to be DIII-D specific. Some parts are the same for NSTX (and are used), but I would consider that an exception rather than the norm.

I also think leaving pf_current with different units/interpretations for different elements is confusing for any use case besides EFIT and does not follow the IMAS definition (pf_current specifies it should have the same size as pf_active.coil and pf_active.coil[:].current is defined as the measured current in a single turn).

My second choice would be the first option, which should be fine temporarily since this isn't being used anywhere yet.

[github-actions[bot]]

Stale pull request message