Validation Gallery¶

This page collects the current validation figures from the active validation ladder. Figures embedded inline are committed compressed copies under docs/media/. Full-resolution legacy campaign figures live on the validation-artifacts-2026-04-28 GitHub release; because this repository is private, release-hosted images cannot render inline for readers, so those are given as download links (they require repository access, or scripts/fetch_example_artifacts.py to restore locally).

The figure classes match the main literature patterns used in verification and edge/SOL validation papers: convergence curves and observed orders (Roy 2005, the GBS parallel-gradient work), profile and target comparisons (TCV-X21, SOLPS-ITER), and differentiable-science summaries (JAX-Fluids and related JAX solver papers).

Figure Status¶

Figure	Status	Meaning
Linear Dispersion / Linearized DRB	native_exact	Drift-wave, shear-Alfven, interchange dispersion reproduced to machine precision.
Hasegawa-Wakatani Turbulence	native_exact	Linear growth matches the B2 eigenvalue; differentiable end to end.
Fluid 1D MMS Convergence	native-validated	Manufactured-solution observed orders on the promoted 1D fluid lane.
Open SOL Two-Point Steady State	native-validated	Mach 1 targets, half-upstream target density, roundoff-closed sheath accounting.
Recycling / Detachment SOL	native-validated	Neutral cushion, detachment onset, SD1D target-flux rollover, differentiable control.
Rotating-Ellipse FCI	genuinely non-axisymmetric gate	Autodiff metric; order-2 direct and traced parallel gradients; shape-differentiable.
Stellarator Turbulence (closed/open)	native_operational	4-field interchange with limiter SOL drainage on the rotating ellipse.
Stellarator FCI Validation	native non-axisymmetric gate	Full-metric, field-line-map, operator, sheath/recycling, neutral, vorticity campaigns.
VMEC-Extender Edge Field Import	self-contained synthetic imported-field gate	Field-grid import, FCI maps, compact SOL smoke coupling on synthetic NetCDF fixtures.
ESSOS / VMEX Imports	external geometry import gate	Coil-field tracing, Poincare extraction, VMEC surface registration, traced-iota verification.
Autodiff Diffusion Sensitivity / UQ / Inverse Design	differentiable validation	Gradients vs finite differences, covariance pushforward vs Monte Carlo, gradient-based recovery.
Strong Scaling	supporting performance audit	Sharded FCI CPU scaling, single-GPU comparison, fixed-work diffusion scaling.

Linear Dispersion And Turbulence¶

Every analytic limit of the dispersion operators is reproduced to 1e-12–1e-16 in tests/test_linear_dispersion.py, and the nonlinear Hasegawa-Wakatani flagship reproduces the B2 eigenvalue to machine precision (tests/test_hasegawa_wakatani.py). Pages: Linear Dispersion Benchmark, Drift-Wave Turbulence.

Fluid 1D MMS Convergence¶

An explicit manufactured-solution refinement bundle for the promoted 1D fluid density, pressure, and momentum operators: per-resolution L2 errors and observed orders on the same native lane used for the compact verification tests. Details: Fluid 1D MMS Convergence.

Open SOL, Recycling, Detachment¶

The open-slab two-point steady state, the coupled recycling SOL with the hermes-3 AMJUEL reactions, the SD1D detachment rollover, and gradient-based detachment control. Gates: tests/test_open_field_line_sol.py, tests/test_native_recycling_sol.py, tests/test_native_detachment_sol.py, tests/test_detachment_control.py. Pages: Open-Field-Line SOL, Neutrals and Recycling.

Rotating-Ellipse FCI¶

The classical rotating-ellipse (l = 2) stellarator — the canonical minimal non-axisymmetric field. Its metric is built by automatic differentiation of the analytic embedding (exact, and differentiable with respect to the shape), and the FCI parallel gradient converges at second order for both the direct and the traced-field-line operator. Gate: tests/test_rotating_ellipse_fci.py; page: Rotating-Ellipse FCI. Regenerate:

PYTHONPATH=src python examples/stellarator/rotating_ellipse_fci.py

Stellarator Turbulence And Geometry¶

The 4-field closed-vs-limiter-open comparison (examples/stellarator/stellarator_turbulence.py), the island-divertor stochastic SOL, and the synthetic stellarator FCI validation campaign (geometry/metric checks with inverse residual ~1.44e-14, operator MMS convergence with observed orders ~1.9, sheath/recycling and neutral balances closed to roundoff, metric-weighted vorticity inversion to ~1.3e-3). The campaign numbers and per-campaign figures are documented in Stellarator FCI Validation.

Imported Geometry (ESSOS, VMEC, VMEX)¶

ESSOS-owned field evaluation, adaptive field-line tracing, and Poincare extraction exported into portable artifacts; VMEC surface registration; the VMEX adapter with traced rotational transform matching the wout iotaf profile to ~1e-6. Pages: ESSOS Field-Line Import, ESSOS Imported FCI Validation, VMEC Extender Edge Fields.

Differentiable Validation¶

• jax.grad sensitivities match centered finite differences on all promoted design parameters;
• first-order covariance pushforward agrees with vectorized Monte Carlo on scalar and field quantities of interest;
• the inverse-design loop reduces the objective from about 2.95e-3 to about 5.52e-5.

Details and commands: Autodiff And Scaling Examples.

Performance Evidence¶

Measured turbulence throughput, gradient-method costs, sharded FCI strong scaling (7.4x at 16 CPU shards; ~96x on one A4000 vs one CPU shard), and the fixed-work diffusion scaling audit. Context and caveats: Performance And Differentiability.

Legacy Campaign Artifacts (release-hosted)¶

Earlier campaign bundles remain on the validation-artifacts-2026-04-28 release for maintainers: the diffusion/vorticity short-window parity figures, the restartable-diffusion demo panels, the diverted-tokamak and TCV-X21 movie packages (their regeneration example scripts have since been removed; the builder module src/drbx/validation/diverted_tokamak_movie.py is still tested), the per-campaign stellarator FCI figure set, and the ESSOS imported DRB movie QA bundles. Restore locally with:

python scripts/fetch_example_artifacts.py

Asset names for the per-campaign figures are listed in Stellarator FCI Validation and ESSOS Imported FCI Validation.

Regeneration¶

The current inline gallery is regenerated entirely by committed example scripts (examples/tokamak/, examples/sol/, examples/stellarator/, examples/benchmarks/, examples/autodiff/) plus scripts/run_fluid_1d_mms_convergence.py — no external inputs required. The imported-geometry figures additionally need the ESSOS or VMEX checkout named on their pages.