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Re: FUN: high-speed electrostatic air-threads



On Tue, 16 Jun 1998, James Mclean wrote:

William Beaty says:
stream of air. I have a needle at large negative potential wrt earth,
and a 30cm stream of fast-moving air of 1mm diameter being shot from
the needle's tip.

This may be splitting hairs, but what evidence do you have that there is
actually a stream of air, as in a wind? For instance, when such a wind
reached the water surface, it would have to go somewhere - I would expect
to be able to see some disturbance other than the furrows you described.

To throw out an alternative, could the furrows be caused by charging the
mist particles, which then would repell each other away from the charging
site? This would require much less mass transport between tip and water.
Would this also be consistant with your observations?

A very good point. Normal "electric wind" is definitely an air flow.
For example, it
is used with those "electric pinwheel" demo devices placed on the terminal
of
tabletop VandeGraaff machines (a swastika-shaped pinwheel with
tangentially directed needles). The "electric pinwheel" is driven by
reaction from the jets of "electric wind." These "threads" I'm seeing are
not a normal electric wind as far as I know, so they might not even be a
linear flow. They could be something more like the plasma fingers within
a "plasma globe" display, or an electrically oriented fiber of mist
droplets, or "nitrogen ion polymer" or something.

However, if you direct an "air thread" towards your hand, you can feel
cold air. If you direct one at bare (no mist) water, you see a tiny dimple
in the water's surface. If you direct one at the mist and examine the
impact point, you will see a fast torodial air flow at the water's
surface, as if a fast thin jet is impacting there. If you jerk the
emitter-needle suddenly, the spot in the mist responds after a short
delay, as if the ion stream is a jet having a velocity of a few
meters/sec. And most telling: if you place a sharp needle within the mist
layer, pointing upwards, then a long white stream of entrained mist jets
upwards several inches (and within the axis of the 5mm dia. mist-stream
one can see a black line, undoubtedly the actual ion stream of <1mm
diameter.

All this is described at:
http://www.eskimo.com/~billb/weird/unusual/airthred.html

(along with lots of partially crack-brained speculations, such as
rainmaking schemes and dot-matrix printers which write on stratus
cloudbanks ;)

Another thought: rising smoke from a factory chimney might act differently
than a rising ion-cloud from an ion generator, since electric fields apply
forces to individual atoms, while bouyancy forces only affect entire
populations of atoms in a hot gas. Since the forces at the fluid's
micro-level are different, perhaps this affects the initiation of
turbulence (since turbulence grows from "seeds" at the micro level.)
Maybe a huge ion-generator would launch a giant laminar spear-like upwards
flow. Negative ions would be driven upwards by the natural
earth/ionosphere voltage.

Laminar flowing Ion-stream sheets, if directed along an aircraft wing,
might eliminate turbulence, and might even eliminate the attached
shockwaves of transsonic flight. Perhaps all that would be necessary is
to give the aircraft a large voltage wrt earth, for example by converting
the jet engine into an ion source (the aircraft would quickly attain a
large opposite charge.)


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William J. Beaty SCIENCE HOBBYIST website
billb@eskimo.com www.eskimo.com/~billb
EE/programmer/sci-exhibits science projects, tesla, weird science
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