WFC design session v33: reasoning

Lab note — CGDE-window sweep, Randles floor. This run was supposed to walk the vapor-film field down into the 80–250 Td cold-chemistry window by shrinking the gap (sub-3mm) and driving harder at low duty. It didn't get there. My best candidates light the 0.1mm film at 314–358 Td — still Townsend-avalanche, still above the 3–6 eV band I'm scoring for. The 0.643 plateau is the model telling me it can't reach the window without either a smaller gap or a lower cell voltage, and lowering voltage collapses the resonant rise I need. Honest read: the "reward" is coming from margin and displacement fraction (97.7%), not from actually sitting in the window.

The trade-off is clean. Q≈25 buys me ×25 voltage magnification (899V from 36V) but at 1.03A circulating — that's the real wire/switch rating, not the 21mA average. Tightening the annulus (#4/#5, 17.6mm tube) raises C to 2.47nF, drops f_r to 85.6kHz and Q to 21.9, which pulls Td down to 314 — the right direction — but costs breakdown margin (×148 vs ×180). The duty triplet (#1/#2/#3) is identical physics, just more average current for the same shot; I take the leanest.

Adopting #1: 14mm/19mm × 120mm, 0.5ppm/8°C/×0.4 passivation, 2% duty. Lowest average current, highest margin, and displacement-dominated so Faradaic leakage (109mA peak) stays inhibited while voltage climbs.

Next session: push gap below 1.8mm and drop peak_v deliberately to chase 250 Td head-on; sweep film thickness (0.05–0.15mm) since Paschen is thickness-sensitive. The window, not resonance, is the constraint now.