VIC design session v27: reasoning

Choke sweep, session note. I pushed L up to drag f_r into the practical 1-100kHz drive band with the AWG18/20-turn winding held fixed. The physics is a clean trade and it's frustrating: the only candidate that lights the vapor film squarely in the cold-chemistry window (#1, 129 Td, 324V cell) sits at 304kHz — out of band by 3×. Everything I do to pull f_r down by raising L also collapses tank Q, and with it the voltage magnification and the film field.

The chain is unavoidable: bigger L → lower f_r, but Xc climbs and the ionic branch shunts less, so effective damping rises and Q falls (27 → 8.5 → 4.3 → 3.5). Lower Q means less step-up (×27 down to ×3.5), lower cell voltage, fewer Td across the 0.1mm film. Current restriction stays comfortable — every in-band candidate is well under 1A (85mA down to 15mA), so <1A is NOT the binding constraint here. The binding constraints are band compliance and film ignition, and they pull opposite ways.

I'm adopting #2: L=1mH, f_r=95.5kHz, Q=8.5, 102V cell, 85mA, all constraints satisfied. It's the best in-band film field I can get (41 Td) without violating the drive band, and it's the honest build point. #1 stays flagged as the physics target I can't yet reach legally.

Next session: stop fighting Q with L alone. Sweep electrode surface treatment (×1→×5) and drop ppm toward 1 to shrink the ionic shunt and lift displacement current, recovering Q in-band. Also test cell length 25→15mm to raise field per volt at #2's 102V.