What do we mean by "first wall" in the wall IDS?

[hrdoktorx]

Hello,
I am looking into filling in some data to the wall IDS from SOLPS-ITER (Wide Grids) results. However, there is an ambiguity in the description of many quantities in which they refer to the "first wall", and a naïve reading sometimes makes one think that the full contour is meant, and in other cases, that the divertor is to be excluded. For instance:
first_wall_enclosed_volume seems to indicate that we have a fully closed unique contour (which would mean it includes divertor structures)
but first_wall_power_flux_peak seems intended for the power flux peak on the main chamber wall, since the same quantities are also present in the divertors IDS, so would lead to duplication if we use the same "full contour" meaning for both.
Thus, I think we need to clarify what is meant by "first wall".

[olivhoenen]

Indeed, we should definitely stop having descriptions in the IMAS Data Dictionary that are only paraphrasing the name of the field, like:

[imbeauf]

It is true that there is some duplication between the wall IDS and the divertor IDS.
The wall IDS takes a geometrical point of view, i.e. the limiting surface for the plasma, and aims at describing all first wall components (including baffle, divertor, ...) in a unique way. I think deciding to exclude the divertor for this unified description would create issues for some workflows.
The divertor IDS takes a system-based approach and describes divertor substructures (divertor/targets/tile) in a detailed way. And with a lot of physics processes details that we don't have on the more engineering-oriented wall IDS.
Maybe we should come back to why the divertor IDS was created ?

[hrdoktorx]

Not really helpful, but OK. Does that mean, that, since the power flux maximum will almost always be located at one target or another in diverted operation, it will not be possible to quickly get the maximum power load on the main chamber wall (which engineers would like to know)?

[imbeauf]

During the discussion we had on the 11th of July, we agreed that we just need to clarify that the current first_wall_power_flux_peak quantity includes the divertors, and to create a new quantity explicitly excluding the divertors.
A PR has just been created