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Re: mist maker / electrostatic motor



This is not Bill.

My reference is A lecture by C. M. Turner during the Course in Nuclear Physics for
Engineers given @ UCB 12 March '46

!st belt generator @ Princeton 1931 -- drawing. shows + 10 => 50 kv. "sprayed" on the belt
using needles (corona discharge) and removed by a second set of needles inside the dome.
The second drawing. shows the arrangement whereby 1.5 mv. is obtained by "ferrying" down a
negative current on the other side of the belt.

The next drawing. shown the round hill generator(s) with the accelerating tube between two
domes one neg, the other pos.

The remainder of the lecture is about insulation, ion energy control, voltage measurement
(motor driven quadrant electrometer!), ion source, mag. deflection, voltage distribution
system using corona gaps, etc.

The point is the "big boys" use an external source of current (x-ray power supply
technology) to "spray" on the belts, while the amateurs use "triboelectricity." I doubt
that any common place batt. would supply sufficient voltage to reverse the "natural"
polarity determined by the tribelectric series. Expt.: replace the rubber belt or the
pulleys with another material, or try, with an additional set of needles, applying @ least
10 kv., as you suggested, using a Wimhurst generator.

Here's a question many of you (I presume) know. If I'm correct in assuming that the
charge ferried up is generated by the separation of the belt from the bottom pulley, what
is the purpose of the bottom set of needles?

bc

I await Bill.

Leigh Palmer wrote:

On Wed, 17 May 2000, Leigh Palmer wrote:

I think heating of the air drives the whirligig. I've never given
the "conventional" explanation.

Then it would behave as a ramjet? Or would the geometry of the hot region
somehow cause air to be ejected from the tip of the needle?

Expansion of the air near the tip may push everything in its vicinity
away, including the tip. The effect is independent of polarity; that
is the reason for my conjecture. What has a ramjet to do with it?

A van de Graaff Generator is self-excited. If it is symmetrical
(top and bottom takeoff brushes identical) it should be possible to
produce either polarity of charge on the dome. I've tried initially
biasing our vdG with a battery, but I always get the same final
polarization direction. Should I try a Wimshurst to bias it?

I figure if anybody would know, Bill will, and everyone else will
want to hear his answer.

Leigh