Re: [TCML] tesla coil blowers

[Ben Hatton <hatto018@xxxxxxxxx>]

On 11/26/2011 2:13 PM, Carl Noggle wrote:
> You're right.  The pressure at the Paschen minimum is what is in a 
> thyratron, OMs lower than atmospheric.
>
> ---Carl
>
>
>
> > 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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In a nutshell it blows out the ionized air making the gap more reliable 
and accurate.  I use a squirrelcage fan on a 1/2 hp big old motor.  
Never heard the pressure thing, true the pressure changes slightly with 
the movement of the air, (think airfoil)  but I say that if they make 
the gap better its because the moving air does not allow the gap space 
to be heated.  Think (jacob's ladder)

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