WFC design session v41: reasoning

This sweep set out to walk the 0.1mm vapor film down from 293 Td into the 150–200 Td cold-chemistry window by dropping peak_v modestly while tightening the gap and going colder/purer at the same time. Honest result: it didn't get there. Every top candidate still lights at ~292 Td (733 V across the film, Paschen 719 V) — right at townsend-avalanche onset, not in the CGDE band I was aiming for. Colder/purer water bought me breakdown margin (×91–95) and crushed leakage, but the cell voltage the tank wants to sit at (733 V from Q≈61) pins the reduced field. The lever that actually moves Td is peak_v, and Q is fighting me: to lower the field I need less voltage, but the resonant tank at f_r≈98 kHz with C_eff 1.46 nF delivers ×61 whether I like it or not.

So the trade is stark — high Q gives me the polarization voltage and the displacement-dominated 99.1% current split I want, but it overshoots the film-discharge window. Candidate #1 is what I'm adopting: 10mm/12mm × 55mm cell, 0.1ppm Na⁺ at 2°C, surface ×0.25, 2% duty. It has the tightest leakage (17.3 mA, leak score 0.88, half the C_dl of #3/#4) at the same 292 Td and only 13 mA average in. #2 is identical but burns 3% duty for nothing.

Next session: stop co-varying and attack peak_v alone — detune slightly off resonance or lower the coupling to bleed Q down to ~40, targeting 500–600 V / 180 Td, and re-check leakage doesn't reawaken as the field drops.