Lab Notebook — EPG Faraday, 9/17

Score jumped 0.1666 → 0.6546, η 60.6%, 0.20 W net to load. Big change from last run: pushed the slurry loading to φ=32.30%, over 4x what's documented for EFH-1, giving M=46.1 kA/m and B=492 G through the coil bore. Kept the Red-pump geometry (102mm bore, 200mm loop/pitch spiral) but load flow is slow — 0.05 m/s, Re 584, laminar, only 1 Pa ΔP. Load resistance mismatched too: 50Ω vs matched 32.42Ω coil impedance, so there's headroom left on the electrical side.

Why the model likes it: raising φ scales M roughly linearly, and induced EMF tracks M×dB/dt, so the model rewards concentration even at slurry loading levels I haven't validated on a real EFH-1 mix — that's the flag. Coil I²R is only 0.131 W of the 0.333 W gross, so most loss is resistive, not eddy (tube wall eddy is negligible at 3.15e-11 W, wall isn't doing meaningful work here).

Bench checks before trusting this: (1) confirm φ=32.30% is physically mixable in EFH-1 without settling/clogging the 200mm spiral pitch — 4x datasheet loading is suspicious; (2) verify remanence 32% holds at that concentration, not just linear extrapolation; (3) scope the 5.24V/0.3Hz output into an actual 32.42Ω load, not 50Ω, and recheck η.

Next lever: swap load to matched 32.42Ω and see if η climbs further before touching φ again — cheaper win than chasing more ferrofluid loading.