I happened across a device called a "Water Breaker" in a garden supply
store. A shower head by any other name, and it fits on the end of a
garden hose. Forget pipettes, this should make a REAL "Kelvin's
Thunderstorm". With thunder, even!
I tried sending a shower through the center hole of an aluminum bundt pan
while the pan was suspended from nylon fishing lines. I collected the
water with a strainer, then connected an old-style 20uA analog meter
between the strainer and earth-ground.
When about 10KV was placed on the bundt pan, the meter read 2.5uA. Not
bad, some tabletop VandeGraaff machines only put out a few uA. When I
disconnected the power supply, the current remained, and it only vanished
when I touched the bundt pan with a finger. I bet that Kelvin
Thunderstorm devices would work much better if we could prevent the
inducer rings from being discharged when a spark acts to discharge the
collector cans.
Before I discharged the bundt pan, over 30 seconds I could see no decrease
in current. Interesting, because I had never looked at the Kelvin device
as being an E-field to current converter. I bet if I removed the bundt
pan, I could use the remaining setup to crudely measure e-field. Whatever
fields hit the tips of the water jets will end up as a microamps reading
on the meter. A hydrodynamic electrometer, with no power supply other
than water pressure. To measure the earth's field, I'd have to make an
upwards-pointing fountain. (This suggests that the spray around a
waterfall, etc., is going to be negatively charged because of induction
from the positive ionosphere.)
The long bundtpan time constant also indicates that nylon fishing line is
a great insulator for use in high humidity conditions. Very little
surface area, and the length of the insulator can easily be made enormous.
Now I gotta think of a good collector. Maybe a dryer-hose toroid with
some window-screen across the hole...