Linear A scaling
UntestedSame V, d, κ — different emitter areas. Thrust should scale linearly with A.
What this test isolates
Premise. Active electrode area is a multiplicative factor in the parallel-plate force formula.
Why it matters. Distinguishes a true electrostatic stack from a single-point corona effect. Doubling area should double thrust if the framework is right.
Formula. F ∝ A (at fixed V, d, κ)
Variable. Emitter projected area A (mm²)
Hold constant
- Same dielectric, same ground plate, same voltage
- Same emitter geometry class (e.g. discs of varying diameter, not discs vs nail arrays)
Prediction. Thrust ratio between two emitter areas equals the area ratio: F₂ / F₁ = A₂ / A₁.
How to run this test
- 1
Pick same-class emitters at different sizes
E.g. 0.8″, 1.2″, 2.0″ copper discs of identical thickness. Or three nail emitters with different point counts.
- 2
Run each at the same voltage
Lock V and d; only swap the emitter.
- 3
Plot F vs A
Should be a straight line through the origin. A non-linear fit suggests fringe-field dominance — try larger areas or a tighter ground plate.
Pitfalls
- !Switching emitter class (disc → nails) midway changes the active area calculation entirely.
- !Edge effects dominate small emitters — start with at least 50 mm × 50 mm.