Core Pressure Map
The 2-D plasma pressure distribution, reconstructed in flux coordinates from Thomson scattering, interferometry, and magnetics, is the fabric's richest engineered feature.
What the map is
The core pressure map is the plasma pressure p = n*(T_e+T_i) resolved across the cross-section, expressed in normalized flux coordinates. It is the feature that ties together density, temperature, and equilibrium, and it is what the twin's Power and MHD modules consume to judge stability and performance in the breeder (Hyperion).
The diagnostics that build it
- Thomson scattering provides local electron temperature and density at multiple radii.
- Interferometry provides line-integrated density, inverted against the reconstructed geometry.
- Magnetics and the equilibrium PINN provide the flux surfaces the profile is mapped onto.
- Ion temperature enters from fast-ion and spectroscopic diagnostics where available.
Reconstruction, not interpolation
The map is a constrained inversion: profiles must be consistent with the equilibrium (pressure is a flux function to leading order) and with all measuring diagnostics simultaneously. This is why flux-coordinate normalization comes first. The result is a field that respects physics, so gradients at the negative-triangularity edge (delta -0.30) are physically placed rather than smeared.
Why it matters
Pressure gradient drives both performance and instability. The map feeds the instantaneous Q estimate, the MHD stability check that watches for pressure-driven modes, and the control that maintains the ELM-free negative-triangularity regime. A dropped Thomson channel is imputed over the sensor graph so the map stays continuous, with the imputed region carrying a reduced quality score.
The pressure-map pipeline is validated in simulation and is a design specification for the FOAK machine whose construction begins Q2 2027.