This browser-side companion uses a simplified Green’s-function model in the poloidal cross-section, but it now includes a boundary-fitted Grad–Shafranov-style inverse step. The active ITER preset now uses the public DINA-IMAS rectangular CS/PF winding-pack model, together with a plasma current found either from a boundary-fitted GS profile solve or from simpler reference models. Start from the full preset configuration, then turn families on and off to see how each contribution bends the flux.
ITER uses the imported public CS/PF rectangle set. SPARC and DIII-D are temporarily disabled until their coil packs are curated to the same standard.
The Cerfon-seeded ITER mode starts from the same D-shaped boundary family used in the Cerfon explorer, then fits both the plasma R p'(ψ) / F F'(ψ)/R source amplitudes and the active external coil-family scales so the target boundary becomes as close as possible to an isoflux contour while matching the chosen plasma current. The boundary-fitted mode only adjusts the plasma profile amplitudes for a fixed external-coil mix; the free-boundary mode keeps the older moving-mask Picard iteration, and the superposition mode keeps the original prescribed source for decomposition-only viewing.
Controls how hollow or peaked the pressure and current source functions are through (1 - ψN)α.
0 biases the plasma current toward the pressure-like R p'(ψ) family, while 1 biases it toward the toroidal-field F F'(ψ)/R family. In the boundary-fitted mode this acts as a prior, while the solver still adjusts both amplitudes to flatten the target boundary.
Awaiting solve.
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∇⊥2ψ = -C jφ
together with the 2D Green’s function
G = -(1/2π) ln[(R-R’)2 + (Z-Z’)2].
External coils are represented as finite coil packs, each approximated by a small grid of toroidal-current filaments projected into the poloidal plane. In the iterative mode the plasma update uses a Grad–Shafranov-inspired source family jφ ∼ (1-ψN)α[(1-\lambda)R p'(ψ) + \lambda F F'(ψ)/R] before renormalizing to the chosen total plasma current.
In the Cerfon-seeded ITER mode those same profile families are used as a D-shaped seed and fitted together with the active external coil-family amplitudes. In the boundary-fitted mode the plasma families alone are adjusted so the prescribed plasma boundary becomes as close as possible to an isoflux contour while satisfying the chosen plasma current.
The dashed green curve is the full Cerfon-seeded plasma boundary used as the ITER target LCFS. The black contour is the active total-field separatrix estimate, while the optional green and blue overlays show the plasma and PF-coil flux families directly. The colored focus contours still track whichever single family or total field is selected in the component table.
The lineout along Z = 0 shows how the active total field and the individual families contribute to the vacuum-plus-plasma flux balance across the machine.
The total-field trace measures ψ(θ) - ⟨ψ⟩ around the target boundary. A perfectly self-consistent equilibrium would leave this curve flat.
The curve uses the closed flux contours from the current iterate and reports a normalized geometric safety-factor shape q/qedge. In this reduced model it is the profile shape, not the absolute normalization, that is trustworthy.