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Re: Elementary Lecture



   This question is not adversarial. I simply do not know for sure: Do Van De
Graff Generators produce open air discharges? I've only witnessed their
operation
a few times, and they were modest devices, except for possibly some dim
recollections of high power versions seen in films.
   If memory serves, they only produce discharges that terminate at a
grounded or
non grounded object.

   BTW, the discussion my original question produced has been very
interesting and
educational.
Dave H.

Tesla List wrote:

> Original Poster: David Trimmell <davidt-at-pond-dot-net>
>
> >>
> >> Brian Basura's coil doesn't even seem to like ground rods, even though
> he is
> >> producing healthy 4-5 ft arcs!  Yes, I'm sure the rod and the bottom
of his
> >> secondary were adequately grounded... Is there a scientific
explanation for
> >> this
> >> or is his coil just "confused"? hehehe
> >>
> >> Anyone have any ideas on this one?
> >
> >My explanation for the "ignoring the ground rod" phenomenon: the
> >voltage is not high enough for a direct leap. Instead, successive
> >sparks grow in the tracks of their predecessors.
> >
> >Malcolm
> >
> >
>
> Yes, and at such a high frequency the time between pulses is so short that
> the ion trails have not had time to dissipate, so the discharge "grows"
> upon itself. At 60 Hz the time between max voltages is so long that the ion
> trails have mostly dissipated, so it takes more voltage to breakdown a
> specific distance through air. Correct? Now if we had a very high voltage
> DC source with continually supplied energy then we should see a similar
> open air discharge, i.e. a VandeGraaff Generator.
>
> It is certainly weird too see a coil sending out 4' streamers, and place a
> ground source at, say 3.5', and have the streamers completely ignore it.
> But, if you leave it there long enough it will get hit, at least that is my
> experience.
>
> Regards,
>
> David Trimmell