I see a couple of issues with the gap design.
In a good gap design, you want the arcing surface to be as wide-spread as
possible, so that its not concentrated in one point. A single point will
get hot, leading to variable breakdown voltages, accelerated wear
(ablation) at the point of arcing, and poor quenching. With your spherical
electrodes, the arc will more or less always be at the same point - closest
to the other electrode.
It sounds like you are intending to use a vacuum pump to evacuate the air
from the tube. Having rarified air is actually a bad thing as far as
quenching goes. You would actually want pressurized air. But more
importantly, you want vigorous air flow through the arc channel, to cool
the electrodes and to remove ionized gasses. I thought that's what you
were using the vacuum pump for but looks like not. I'd again suggest using
a sucker gap.
Regards, Gary Lau
MA, USA
On Mon, Feb 17, 2014 at 4:23 AM, Kuba Anglin <kubaanglin@xxxxxxxxx> wrote:
> Thanks for your response,
>
> Sorry I was not very clear on my spark gap design. Here is a rough rendered
> image of what it will look like. A vacuum pump will suck the air from the
> tube to lessen the air resistance for greater control over the spark gap
> and limit ozone production for obvious reasons.
> http://s29.postimg.org/t4o3jgapz/spark_gap.jpg What do you think? Is it
> worth the benefits?
>
> Thanks,
> Kuba Anglin
>
>
> On Sun, Feb 16, 2014 at 6:46 PM, Gary Lau <glau1024@xxxxxxxxx> wrote:
>
> > Hi Kuba,
> >
> > There's nothing wrong with adding a sphere atop a toroid. However, the
> > incremental capacitance of the sphere, assuming your image is to scale,
> > will be rather small, as the shape of the toroid will shield the field
> from
> > the sphere. I think just adding an extra primary turn would probably
> have
> > a greater impact at lowering Fres than the added sphere.
> >
> > If you're shooting for the maximum spark length, I think the size of your
> > toroid needs to be up'ed considerably. With my 15/60 NST, I use a 7x30
> > primary toroid with a smaller corona ring toroid spaced beneath it, to
> gain
> > additional height for the main toroid. With top loads, bigger is
> _always_
> > better.
> >
> > I didn't completely understand the geometry of your gap. I don't think
> > there's any good reason to try to contain the gap arc. PVC, and
> > particularly rubber (!), will suffer rapidly from exposure to the UV
> > radiation of the gap. I think the gap will generate the same amount of
> > ozone whether or not it's contained, assuming that the air is circulated
> > and not sealed, and you DO want good circulation. And in any
> > well-performing coil, the sound from the top load sparks will be much
> > louder than the sound of the gap, so no point in trying to muffle it. I
> > would recommend a sucker gap - it's been widely tested and is easy to
> > construct and adjust. See http://www.laushaus.com/tesla/onegap.htm
> >
> > Hope this helps,
> >
> > Regards, Gary Lau
> > MA, USA
> >
> >
> >
> >
> > On Sun, Feb 16, 2014 at 8:03 PM, Kuba Anglin <kubaanglin@xxxxxxxxx>
> wrote:
> >
> > > Hello,
> > >
> > > I have been working on a Tesla coil design for the past month now and
> am
> > > about ready to order the parts.
> > >
> > > My main questions:
> > >
> > > -Are there any issues with my design?
> > > -Is it OK to have a toroid and a sphere as the top load? I am only
> doing
> > > this because these two pieces equal the required capacitance level of
> > > around 29pF (see the TeslaMap image for more info).
> > > -I was planning on creating a vacuum static spark gap by putting the
> > > electrodes inside a PVC pipe sealed with rubber sheets and lexan board.
> > The
> > > vacuum pump would suck out the air to limit resistance caused by the
> air,
> > > lessen ozone production, and reduce noise. Does this sound like a good
> > > idea?
> > >
> > > I have added a 3D render of my design and a filled out TeslaMap page. I
> > > will be phasing two NSTs to achieve the right amperage. Check the
> > TeslaMap
> > > attachment for more specific specs.
> > >
> > > 3D render link: http://s13.postimg.org/q9tpxzsjb/Tesla_Coil.jpg
> > > TeslaMap link: http://s9.postimg.org/t0ss08wmn/Tesla_Map_Page.jpg
> > >
> > > Here is my parts list:
> > >
> > > Secondary Coil6.625" PVC Pipe 3'22 AWG Magnet Wire 5lbs wound 34"
> > > highToroid
> > > 18" x 4.5" + Sphere 7" diameterPrimary Coil3/8" Copper Tubing 60' 11
> > > turns1/2"
> > > Copper tubing 10' strike railBase(2X) 15 KVA 60mA Transformer(2X) 1"
> > Brass
> > > Electrode
> > > 72 Capacitors (.15uF 2kV each) 4 strings of 18(2X) Brass Bolt
> > >
> > > Thanks,
> > > Kuba Anglin
> > > _______________________________________________
> > > Tesla mailing list
> > > Tesla@xxxxxxxxxx
> > > http://www.pupman.com/mailman/listinfo/tesla
> > >
> > _______________________________________________
> > Tesla mailing list
> > Tesla@xxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
> >
> _______________________________________________
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>
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