Shunt resistors

[eldond]

Shunt resistors are put in circuit with an electrical connection between the outer and inner divertor plates. When only one of these is detached, the voltage drop across the resistor enables an estimate of Te at the hotter divertor plate.

To make this work as a synthetic diagnostic, I guess we need to identify the area of divertor that's collecting current from the plasma on each of inner and outer, the total current arriving at each of these collection zones (which may or may not be the whole divertor?), and the circuit between them.

In this case, I think we should model the internals of the diagnostic. For Thomson scattering, it's okay to just sample Te and say "the diagnostic just measured this" and skip all the scattered signals and calibrations. But for this diagnostic, I think we need to assess its accuracy and see how to interpret it. For example, if we collect current over a large area, which temperature are we actually measuring? The average? Over what region? We should go through the whole exercise of modeling the voltage across the resistor and the calculation of Te from that voltage drop, then compare it to Te in the SOLPS model.

Related references:
https://doi.org/10.1088/1741-4326/acd947
https://doi.org/10.1016/S0022-3115(00)00445-1
http://dx.doi.org/10.1088/0741-3335/52/5/055002

• Define geometry of the collection zones / which plasma facing surfaces are electrically connected to the resistor
• Using SOLPS results, model voltage across the resistor
• Calculate Te from voltage
• Also record Te sampled at key points at the inner and outer divertor (where divertor leg intersects wall, peak Te at each divertor, average Te across cells bordering the divertor plate)
• Examine calculated Te vs the records directly from SOLPS Te

It seems that this will be much easier when ProjectTorreyPines/SOLPS2IMAS.jl#6 is complete, so I think this issue is blocked until that one is resolved.
Also needs ProjectTorreyPines/SOLPS2IMAS.jl#10

[eldond]

SPARC won't have these. We can still model them for exploration, but the priority is now reduced.