WFC design session v25: reasoning

Lab note — WFC resonant sweep, walking f_r down from 98kHz.

The sweep confirms the geometry-vs-band tension I suspected. Raising C_eff (colder water at 5°C for higher εr, longer and wider tubes) pulls f_r from ~98kHz down to 50kHz as intended, and because I held the choke fixed at 1.7mH, the lower f_r means lower Xl, lower tank Q (70.9→48.8), and correspondingly lower cell voltage per the ×Q multiplier. Series current barely moves (546–550mA) — it's pinned near half an amp by the drive and coil resistance, comfortably under the 1A wall. So current isn't the binding constraint here; the Townsend field is.

Here's the honest catch: the scorer's top three all light the vapor film at 300–339 Td — ABOVE my 250 Td cold-chemistry ceiling. That's a scoring artifact I don't trust; those candidates resonate hard but overshoot into hot-arc territory, which burns electrodes and wastes current on thermal channels, not cold dissociation. #5, though ranked last (0.674), is the only candidate that actually lands the film INSIDE the 3–6 eV window at 234 Td, sub-breakdown regime, with breakdown margin ×170 and displacement current still 98.1%.

I'm adopting #5: 8mm rod in 11mm tube × 200mm, f_r 49.85kHz. Physics over score.

Next session: nudge choke inductance up (~2.2mH) to recover Q and voltage at this larger C without pushing Td back over 250 — decouple voltage from geometry. Also sweep surface treatment ×2–×3 to shrink λ_D and firm up the film onset.