WFC design session v26: reasoning

Design note, 2026-07-18

All five candidates land in the same regime — ultra-pure water (0.1–0.15ppm), near-freezing, ×0.25 surface treatment, same 8-cell/2-choke geometry — and every one of them stalls in townsend-avalanche below the 719V Paschen minimum for the 0.1mm film. That's the real story of this sweep: none of the top candidates actually reach the CGDE window, they're just ranked by how close they get. #1 is the closest at 947V/378Td, still shy of 80-250Td-at-3-6eV territory but pushing hardest against the ladder because it has the highest tank Q (78.9) and thus the highest cell voltage for the same 12V drive. That confirms the trade I suspected: raising Q via colder/purer water raises series current toward the 1A ceiling (635mA here, up from 480mA at #4/#5) faster than it buys me discharge margin — I'm burning current headroom without crossing into avalanche-to-streamer transition. Frequency band barely moved (69.8–71.1kHz) across the whole set, so the Q/current tension is being driven by water resistivity and λ_D, not by detuning.

Adopting #1: best score, current still under 1A, breakdown margin healthy (×566), and it's the nearest approach to the discharge ladder we've got.

Next session: hold purity/temp near #1's values but sweep surface treatment more aggressively (×0.1–×0.15) and film thickness down from 0.1mm — I think the ladder crossing lives in electrode geometry, not water chemistry, at this point.