The relationship between air pressure, electrode gap spacing and breakdown voltage is well documented by Paschen's law/curve.
The breakdown voltage does reduce with pressure to a point but then increases again when the pressure is further reduced. These low pressures are probably much lower than a normal blower could achieve (Wikipedia cites an example of 10^-3 atmospheres).
The probability of a random free ion being pressent to start the breakdown is increased by the quantity of air flowing through the spark gap which would also lend it's self to lower breakdown voltage.
- David
________________________________
From: Carl Noggle<cn@xxxxx>
To: Tesla Coil Mailing List<tesla@xxxxxxxxxx>
Sent: Saturday, 26 November 2011 4:06 PM
Subject: Re: [TCML] tesla coil blowers
Hey---Sounds like a reasonable theory. There should be a gap length for
max performance corresponding to each blower speed. I'll check it on
mine--it's an annular blower gap. I'll report findings.
---Carl
Though no one asked, I'll offer my theory. The air between the electrodes
in a sucker gap is at a lower pressure than the surrounding atmospheric
air. As the pressure is reduced, the breakdown voltage of the gap is
reduced. A lower breakdown voltage delivers smaller bangs, and lower
performance. Just a theory though - I haven't run my sucker gap in many
years and I haven't personally witnessed this.
Regards, Gary Lau
MA, USA
On Fri, Nov 25, 2011 at 6:29 PM, Jonathan Peakall<jpeakall@xxxxxxxxxxxx>wrote:
I found with my sucker gap that too much vac actually decreased
performance. There was a sweet spot somewhere around the 20-30% power mark,
as Gary describes.
Jonathan
----- Original Message ----- From: "Carl Noggle"<cn@xxxxx>
To: "Tesla Coil Mailing List"<tesla@xxxxxxxxxx>
Sent: Friday, November 25, 2011 8:04 AM
Subject: Re: [TCML] tesla coil blowers
Thanks, Gary--after 20 years of running my coil I never thought of
that. Probably make for longer motor life, too, although in that time I
have only had to replace it once. Still, I had egg on my face in the
middle of a show. A small step-down autotransformer would work well, too.
---Carl
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