test: validate SIMPLE Boozer chartmap roundtrip and VMEC benchmarks#332
Merged
krystophny merged 5 commits intomainfrom Mar 28, 2026
Merged
test: validate SIMPLE Boozer chartmap roundtrip and VMEC benchmarks#332krystophny merged 5 commits intomainfrom
krystophny merged 5 commits intomainfrom
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Add export_boozer_chartmap() that writes computed Boozer data (Bmod, B_theta, B_phi, A_phi, torflux, X/Y/Z geometry) to an extended chartmap NetCDF file after get_boozer_coordinates(). Add roundtrip test that validates the full pipeline: VMEC -> Boozer -> export chartmap -> reimport -> compare Field roundtrip error: ~8e-5 (re-splining) Orbit roundtrip error: ~2e-9 (machine precision) Includes Python plotting script for visual evidence artifacts saved to /tmp/ (gitignored).
Bmod: 1e-3 -> 1e-4 (actual: ~8e-5) Orbit: 1e-3 -> 1e-6 (actual: ~2e-9)
Two fully isolated simple.x runs with identical particles: 1. VMEC-Boozer: standard path reading wout.nc 2. Chartmap-only: reads boozer_chartmap.nc, no VMEC at all Test pipeline: - Run simple.x with VMEC+Boozer (generates start.dat in VMEC coords) - Export Boozer chartmap and convert start.dat to Boozer coords - Run simple.x with chartmap only (startmode=2, loads converted start.dat) - Compare confined_fraction.dat Changes: - export_boozer_chartmap: endpoint-excluded grids, pseudo-Cartesian geometry with atan2(y,x)=phi_B for chartmap validator compatibility - simple_main: skip VMEC magfie init in chartmap mode, require startmode=2 - New export_boozer_chartmap_tool.x for coordinate conversion - Python test orchestrator with comparison plots
The Boozer field data (Bmod) now uses separate endpoint-included dimensions (theta_field, zeta_field) matching the original VMEC Boozer grid exactly. The chartmap geometry (x, y, z) keeps endpoint-excluded grids for libneo validator compatibility. This gives exact spline reproduction: Bmod roundtrip error ~8e-5, orbit error ~1e-9. E2E test at 100ms passes for both QA and NCSX equilibria with at most 1 particle difference out of 32.
Both equilibria show exact match (zero difference) in total, passing, and trapped confined fractions at 10ms. NCSX has significant losses (~55% confined) providing a stringent validation.
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Summary
Add strict VMEC-origin validation for the SIMPLE Boozer chartmap path.
This PR is intentionally limited to VMEC-side export/import and SIMPLE runtime checks. It does not introduce the GVEC converter or figure-8 workflow; that now lives entirely in PR 331.
This layer adds:
Review
Primary SIMPLE-maintainer review: @krystophny