WFC design session v51: best candidate (Q=101.6, 99.5kHz)

Sweep: Finer geometry grid around the adopted 10mm/50mm best while co-sweeping film-relevant levers — moderate gap widening plus colder/purer water to shed Q gently — against a low-duty peak_v ladder and gamma_se, hunting the 80-250 Td / M=0.1-1 sub-critical corner without the already-tried multi-cell or warm-water routes.

Cell: 12mm rod in 14.0mm tube × 45mm, 1 cell(s) parallel → C_eff = 1.39nF, bulk water R = 118614Ω. Water/electrodes (Randles): 0.1ppm Na+ @ 5°C, surface ×1 → λ_D 228nm, C_dl 3.0µF, cell series R 11.1Ω, displacement current 99.0%, breakdown margin ×55. Fig-8 voltammetry (4,798,661): τ_EDL 360402.3µs (35848.9 carrier cycles to charge), Faradaic leakage at peak 111.4mA (leak score 0.48 — keep amp leakage inhibited while voltage climbs the ladder). Vapor-film discharge (CGDE onset, 1220V across 0.1mm film): regime townsend-avalanche, film Paschen 778V, 486 Td — OUTSIDE the 80-250 Td cold window. Townsend α/γ: γ = 0.003 (electrode lever), criterion M = γ(e^{αd}−1) = 33127.808 → self-sustaining (M≥1) — γ feedback closed, heading for thermalization. Per-molecule (series micro-capacitor chain): 3.70M molecules across 1.00mm → 329.32 µV/molecule (polarization (µV band)). Chokes: 2 × 0.000919H (20 turns, AWG 18, 2m wire, AC R 0.1Ω each). At resonance f_r = 99.47kHz: Xl = 1149Ω, Xc = 1149Ω, tank Q = 101.6, coil Q = 6530.5. Cell voltage 1220V from 12V drive (×101.6). Tank current 1.06A circulating (CW upper bound — rate wire/switch for this); average input 21mA at 2% duty. No hard violations (band, wire length, dielectric). Average current is scored, not gated. Score 0.763.