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Current-flow null
UntestedForce should appear with negligible leakage current. If high I correlates with high F, you're measuring corona.
What this test isolates
Premise. An electrostatic stack draws displacement current only — leakage I ≈ 0 in a healthy dielectric. Force-from-current means ion wind.
Why it matters. The single most direct discriminator between electrostatic and ion-wind explanations of measured thrust.
Variable. Leakage current I (µA)
Hold constant
- Standard run; add a current monitor in the HV return path
Prediction. F is independent of I to within 20% across the test range.
How to run this test
- 1
Insert a current shunt
100 kΩ on the HV-return / ground side, scope across it for V→I.
- 2
Run a V sweep
Capture both F and I at 5 voltages.
- 3
Plot F vs I
Independence (flat curve, lots of scatter) = framework. Linear correlation = corona.
Pitfalls
- !Probe RC artifacts at HV — calibrate the shunt before claiming a null.
- !Stray surface leakage masquerades as the real signal.