Add electrostatic no-op benchmark case with unconverged-reference finding#181
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krystophny wants to merge 7 commits into
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Add electrostatic no-op benchmark case with unconverged-reference finding#181krystophny wants to merge 7 commits into
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This was referenced Jul 13, 2026
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Closing: the wp5 flux-pumping stack is retired. This work is superseded by the forced-periodicity lineage on |
marjohma
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) ## Summary Extracts the two salvageable pieces of the retired wp5 flux-pumping stack onto the forced-periodicity lineage. The rest of that stack (#177–#181, #184) is closed as superseded. ## Krook argument `z0` (was #183) `interpolate_plasma_backs` interpolated the **derived** `z0` alongside the primitives. `z0` carries a `1/|k_parallel|` singularity at the resonance, so a four-point Lagrange stencil spanning `k_parallel = 0` returns values that violate its own defining formula. The fix interpolates primitives only and recomputes z0 = -(omega_E - omega - i nu) / (|k_parallel| sqrt(2) v_T) on the target grid — the same invariant the periodized-background path already follows. **Scope:** `z0` is consumed only by `Krook_kernel_plasma_prefacs.f90`. The Fokker-Planck path recomputes `x1/x2/A1/A2/I^{kl}` after interpolation and never reads `z0`, so **FP results are bit-unchanged**. This repairs the Krook hat path, whose nml still marks it `(unstable)` — plausibly part of why. ## Collision-frequency scale (was #182) New positive `&KIM_CONFIG` key `collision_frequency_scale` multiplying the calculated electron and ion collision frequencies before `z0` and the FP susceptibility inputs are assembled. Default `1.0` leaves every collision formula, profile, unit, and output unchanged. Non-positive values are rejected at startup; the value is displayed when it differs from 1.0 and stored in HDF5 provenance. Same shape as the existing `ion_flr_scale_factor` knob. No benchmark-acceptance claim — it is a sensitivity parameter. ## Tests `test_collision_scale_z0` (new) asserts the `z0` invariant on a stencil straddling `k_parallel = 0` and away from it, and that the scale reaches both `nu` and `z0` (including the imaginary part of `z0` tracking it). Developed red-first: against the pre-fix code the test fails with a **36% relative `z0` error at k_par = 2e-4** (`got (-0.0983, 0.0129)` vs `want (-0.4543, 0.0599)`), growing without bound toward the resonance. ## Validation - `make` — clean build - `ctest -E 'test_rhs_balance|test_periodic_convergence|test_periodic_vs_global'` — **32/32 passed** Known red gates excluded as usual: the pre-existing `test_rhs_balance` baseline failure, the periodization-deformation gate, and the periodic-vs-global 5% gate — none touched by this change. Supersedes #182, #183.
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Benchmark slice of #175 (no-op comparison against the hat basis), with the
honest outcome: the benchmark cannot gate anything yet, and the committed
case documents why.
KIM/tests/test_data/benchmark_electrostatic/contains a self-containedelectrostatic case (Krook, the profile set of the golden electromagnetic
case), a periodic-solver twin configuration whose layer covers the widest
admissible window for these profiles,
compare_phi.py(raw andgauge-offset-removed L2/Linf on a common window, threshold 5 percent, exit
nonzero on failure), the two windowed profiles, and a README with the
measured numbers and the manual two-command procedure.
Stack: parent
feat/flux-pumping/wp5-driveratfb07a293(#180).Finding
Both solves are unconverged on this case, so no agreement threshold is
meaningful:
by ~11 orders (1.741e10 vs 2.132e-1 statV); offset-removed relative L2
0.975; an optimal complex rescaling still leaves 0.976, so the shapes
are uncorrelated, not misnormalized.
1.072 (not converged).
with the peak growing by 3.6e3: the Krook hat solve diverges under
refinement at omega = 0, consistent with the configuration file's own
"Krook (unstable)" annotation. There is currently no refinement-stable
reference.
No ctest is wired: a threshold on two unconverged solutions either always
fails or encodes the defect. The comparison script and case stay as the
review surface and as the ready harness for the follow-up.
Follow-up this defines
Either a Krook case in a parameter regime where the hat solve is
refinement-stable (finite frequency or higher collisionality), or
continuum FokkerPlanck-form kernels for the periodic side, before the
no-op condition of #175 can be tested. Solver code is deliberately
untouched here.
Verification
Relation to Markus's Fokker-Planck periodic branch
This PR is retained as a negative benchmark record and reusable common-grid comparison harness. It proves that the packaged Krook hat solution is not a converged no-op reference; it does not validate either periodic implementation. Do not tune this case further. The accepted matched FP/Vaclavik benchmark is #190.