Re: Discharge impedance of a CW Tesla coil

To: tesla-at-pupman-dot-com
Subject: Re: Discharge impedance of a CW Tesla coil
From: "Dan Kline" <ntesla-at-ntesla.csd.sc.edu> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Fri, 17 Mar 2000 16:58:28 -0700
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

>>Original Poster: "Malcolm Watts" <malcolm.watts-at-wnp.ac.nz>
>>>
>>> Hi Reinhard, Terry,
>>>
>>> Methinks you are on the right track with relating the ozone production to
>>the
>>> size of the discharge. John Freau reports that he gets considerable ozone
>>> from his VTTC throwing 19 inch sparks. Not only is the 3O2 + energy
>yields
>>> 2O3 reaction unstable, less than
>>> 8% of the available oxygen is utilized before the reaction reverses. The
>>> triatomic
>>> molecule uses 8 % of 20% of the volume of air in the room. So the way I
>seez
>>> it, my little VTTC produces no detectable ozone because the volume of air
>>> within the discharge "sphere" is too small.
>>
>>If that is all true, then why is there little detectable ozone when you
>>create long arcs with an arc welder?  The fact that spark length is
>>mentioned again and again says to me that there is a voltage (read
>>energetic) factor involved. ?
>>
>>Regards,
>>Malcolm

Hmmm....The first sort of "Tesla-coil" I ever built was the "standard"
12-volt dual 2N3055 emitter-coupled oscillator used to drive a reworked
flyback transformer. I could draw about a 1" spark off of that. I used to
take a short piece of very thin wire, about 8", and attach it to the output
of the flyback transformer. Along the length of the wire would be evenly
spaced corona points, and the "corona wind" would drive the wire around in
fast circles, making a beautiful purple cone of light. The room I was
working in would get so choked with ozone that I would soon be choking with
ozone myself ;) There was no discharge at all from this wire, other than
corona.

For several years I worked as a copy-machine technician. Copy machines have
high-voltage DC chargers which are used in part of the copy process. The
chargers are called, interestingly enough, "coronas" or "corona wires" (at
least around here anyway :) The coronas put out a lot of ozone...so much so
that we often had to remind people to not run their copiers in enclosed
spaces. No discharge from those wires either, other than corona. 

The implication, to me, is that ozone production is a matter of frequency,
the lower frequencies and on down to DC producing the most. I'd **guess**
that ozone production might start dropping off when frequencies get above
300 - 450 kHz. It's strange that in a plasma-globe, conduction is
determined by gas pressure (rarification, actually :) for a given voltage
and current at a fixed frequency. I think the regular atmosphere has the
same thing going for Tesla-coils too. I'm thinking that upping, or
lowering, the frequency of a coil would also change the atmospheric
arc-conduction parameters, which might affect ozone production at the same
time. 
Anyway, it's just a thought :)
Dan