RE: Enhancing Corona

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "David Dean by way of Terry Fritz <twftesla-at-qwest-dot-net>" <deano-at-corridor-dot-net>

Hi Scott

For an example of a small coil which produces a lot of corona see
www.corridor-dot-net/deano/medicine_coil.htm

I don't think the secondary frequency is the key. I think that small coils
tend to produce more corona, as well as more ozone, due to the smaller ROC
of the secondary and the topload. A significant amount of corona can be
produced by a relatively low DC voltage if it is applied to a thin wire.
This is used in copiers and laser printers all the time. The production of
corona and also ozone seem to be related to field stress. In larger coils
with larger toploads, the corona is suppressed. A large coil may very well
produce a lot of corona if it is run at a power level just under that
required for a streamer to break out.

I once saw a bright brush discharge coming off the beak of a bird sitting on
a 7.2KV primary wire on a cold, dry, but still night. No corona was visible
from the wire itself, just from the beak of the bird.

later

deano


> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Tuesday, June 19, 2001 7:00 PM
> To: tesla-at-pupman-dot-com
> Subject: Enhancing Corona
>
>
> Original poster: "Scott Fulks by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <darkthing-at-earthlink-dot-net>
>
> I am interested in doing some experiments on normal-pressure plasmas, and
> was thinking of custom-designing a TC to create copious amounts of brush
> discharge as opposed to sparks.  Virtually all of the discussion on this
> forum seems to equate spark length with efficiency, but I am sure
> that many
> coilers have seen configurations which produce more corona than spark
> length.  I'd appreciate any feedback from coilers who have
> (accidentally or
> intentionally) produced a coil that puts out lots of corona.
>
> The way I see it, the secondary frequency is the key parameter for brush
> discharges.  If the frequency is high, inductive effects similar to the
> well-known "skin effect" come into play more prominently.  The
> impedance of
> a single thick spark is so great at high frequencies that the discharge is
> more prone to seek multiple pathways, just as litz wire offers a lower
> impedance to RF currents than a solid copper wire.  Multiple
> small discharge
> pathways are seen as a brush discharge, since the human eye cannot resolve
> the individual lines of current and just sees a uniform glow.
>
> If this is true, then I would expect the length of sparks from a
> coil would
> be in inverse relation to the frequency of the secondary.  A
> lower frequency
> would give longer sparks.  From the discussions of the importance of large
> toploads for spark length on this list, this seems likely.  Large
> topload =
> larger secondary capacitance = lower frequency = longer sparks.
>
> I recall someone on this list awhile back say that small coils seem to
> produce more ozone than larger coils.  Is this because smaller
> coils operate
> at higher frequencies (low inductance secondary), or is there some other
> reason?
>
> Regards,
> Scott Fulks (darkthing-at-earthlink-dot-net)
>
>
>
>