Better handling of non-standard ions when loading from IMAS

[theo-brown]

I've been supplied with an IDS that has "DT" as a main ion name. This is incompatible with the TORAX loader, and plasma_composition_from_IMAS raises an error. How should I load this, or find an alternative route that still lets me load this IDS?? Do we need to add functionality to better support when IDSs have unrecognized ions?

@MateoBell

[MateoBell]

Maybe you could preprocess the IDS and modify the ions before passing it to plasma_composition_from_IMAS ? Maybe we could better support unrecognized ions, but I don't really know how we can handle it without the loader being to heavy.
For your case I guess we have to assume the D and T fractions, and is the density in the IDS the sum of each ion density or the individual one ?

[jcitrin]

For "DT" specifically I think we can recognize this as a bulk 50-50% DT ion, with mass equal to the (A_D+A_T)/2 , and also be recognized in the fusion power module as a 50-50 DT equivalent.

It's a common enough use-case

[theo-brown]

Was there a plan at some point for the user to be able to supply a mapping of IMAS->TORAX names as an arg to plasma_composition_from_IMAS? e.g. plasma_composition_from_IMAS(core_profiles_ids, imas_to_torax_ions={"C+": "C"}?

[jcitrin]

Was there a plan at some point for the user to be able to supply a mapping of IMAS->TORAX names as an arg to plasma_composition_from_IMAS? e.g. plasma_composition_from_IMAS(core_profiles_ids, imas_to_torax_ions={"C+": "C"}?

That sounds good to me, we can make a TODO/issue for that. Note that the DT case is a special case, since it will need extra logic in the fusion power calculation.