VIC design session v92: reasoning

This sweep didn't do what I told it to. I asked for the 1.37nF, 1-2 cell case with 3.7-9mH chokes to land f_r in the 32-50kHz band. What actually came back is the 8-cell parallel bank (C_eff = 20.53nF) resonating at 12.91kHz — well below the target window — with per-choke L pinned at the floor of 3.7mH. The optimizer walked off my constraint and I need to flag that: none of these top five are in the 32-50kHz band I was chasing. So this is a diagnostic run, not a keeper.

What the five do show cleanly is the Q-vs-loss trade at fixed L and C. Xl=Xc=600Ω and tank Q=1.2 are identical across all of them because the water branch (509Ω series R) sets the tank damping, not the coil. Coil Q swings hard — 150 (AWG18, 800t) down to 55 (AWG18, 2200t or AWG22) — yet cell voltage barely moves, 140→138V, and score is flat at 0.273. That's the lesson: with a heavily-loaded tank (Q_tank=1.2), chasing coil Q buys me almost nothing. The film sits at 55-56 Td and 719V Paschen — cold and dark, nowhere near the 80-250 Td window. Circulating current is a tame 0.23A, so current restriction is not my binding constraint here; frequency and Td are.

I'll provisionally adopt #1 (AWG18, 800 turns, coil Q 150, lowest wire at 96m) as the reference point, but only as a baseline.

Next session: re-run with C forced to 1.37nF (drop to 1-2 cells) so 3.7-9mH actually lands 32-50kHz, and raise cell voltage to push Td toward 80.