RE: Sparks to Mid-Air (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Sat, 27 Oct 2007 20:42:14 +0000
From: "Lau, Gary" <Gary.Lau@xxxxxx>
To: 'Tesla list' <tesla@xxxxxxxxxx>
Subject: RE: Sparks to Mid-Air (fwd)

I don't know - I thought the dynamics behind a TC's streamers-to-air were
fundamentally different than what occurs on a VDG.  In a VDG, you might
see and hear small amounts of corona bleeding off into the air, but you
don't get big bright sparks unless there is a direct path at a suitably
short distance to a grounded target.  If the target is too far away, you
don't get the discharge.

In a TC, I believe the difference is that since the HV is at a high
frequency, a current path from the top load to earth exists by virtue of
the capacitance to earth, even if there's not a direct path.  That current
path wouldn't exist if it were a low frequency or DC.  But at this point,
my theory degrades to a certain amount of hand waving, and usually Bert
Hickman chimes in with the proper terminology and a definitive and much
more complex answer.

Regards, Gary Lau
MA, USA

> From: Dave Pierson <davep@xxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: Sparks to Mid-Air (fwd)
>
>
> >This is something that's been bugging me for a while.  I like to
> >understand things that I see and do, but I can't figure out how a Tesla
> >coil can create sparks into mid-air.
>     Same way anything else does.
>     Localized corona breakdown, followed by a visible streamer.
>
> >You'd have to have some voltage generated in the air relative to the Tesla
> >coil topload (I think), but how?
>     Once the field strength exceeds breakdown, corona starts, initially
>     invisibly.  If power is available, one or more path will extend.
>
> > Is this dependent on the frequency at all?
>     On one level:
>      No.
>
>     A van de Graaff will cheerfully spark over to air.
>
>     Details of spark appearance may change.
>
> > Like, would a theoretical Tesla coil operating at a very low frequency still
> > generate sparks into mid-air?
>     The van de Graaff is DC.  'bout as low as it gets.
>
>     best
>      dwp
>
>