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Re: [TCML] High Power Static Gaps
Hi Gary,
I had forgotten that you actually did that comparison of
the vacuum and vortex gaps, and saw the hoped for
reduction in gap losses in the vortex gaps. So it is
not only a theoretical advantage but an actual advantage
that could be measured.
Excellent indeed.
John
-----
-----Original Message-----
From: Lau, Gary <Gary.Lau@xxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Tue, 9 Sep 2008 7:26 am
Subject: RE: [TCML] High Power Static Gaps
Hi Bart,
I agree that the higher pressure gap of the same geometry will have the
higher
breakdown voltage. But if we move the electrodes closer together to
achieve the
same breakdown voltage as the low pressure gap, I think this will
result in a
lower gap resistance and lower gap losses. This was the theory that
motivated
the design of my vortex gap. The comparative measurements I made
between the
sucker gap and vortex gap, documented at
http://www.laushaus.com/tesla/vortexgap.htm,
show that the higher-pressure vortex gap has lower gap losses and
resulted in a
slower ring-down rate of the uncoupled primary.
Regards, Gary Lau
MA, USA
-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
Behalf Of bartb
Sent: Monday, September 08, 2008 11:04 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] High Power Static Gaps
But consider this, high velocity air in a non-pressurized chamber
across
a gap versus high velocity air within a chamber across the same gap
causing pressurization. How do these two gaps differ? It's the
pressure.
And that pressure will increase the breakdown voltage to arc the gap.
With a gap set equally between these two gap types, the pressurized
gap
will perform better since it will require a higher voltage to arc the
gap, summing to a higher energy bang. I think when all things are set
"equal" (breakdown and air velocity), there may not be much of a
difference. I don't see the mechanism for it. I'm not saying there is
no
difference, simply that I fail to see the what it is.
Take care,
Bart
Quarkster wrote:
> Bart -
>
> I'm not sure that I agree that the performance "will be the same".
>
> Certainly, you can increase the width of the non-pressurized gap so
the
breakdown voltage is the same as a pressurized gap. However, one of
the
largest
benefits of of a correctly-designed "pressurized" gap is the
extremely high
air
velocity through the gap. Quenching should be measurably better than
a simple
ventilated TCBOR gap, or even a vacuum gap where the maximum pressure
differential across the gap can never exceed 14.7 PSI. However, I
don't have
comparative data at this point .....
>
> Regards,
> Herr Zapp
>
> --- On Sun, 9/7/08, bartb <bartb@xxxxxxxxxxxxxxxx> wrote:
>
> From: bartb <bartb@xxxxxxxxxxxxxxxx>
> Subject: Re: [TCML] High Power Static Gaps
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Date: Sunday, September 7, 2008, 4:46 PM
>
> The static gap DC Cox has been discussing this last year in various
> postings is just this. It's a simple pressure gap. Nothing special
other
> than the pressure is changed via forced air. A pressure gap changes
the
> air pressure. This increases the breakdown voltage for a given
distance
> and electrode geometry.
>
> With "all things equal", I don't realize longer sparks. All
> things are
> not equal. To equalize the gaps (pressure versus not), increase the
gap
> distance on the non-pressurized gap to equal the breakdown of the
> pressurized gap. At that point, they will perform the same (and
harder
> on transformers because of the higher breakdown voltage).
>
> Regards,
> Bart
>
> futuret@xxxxxxx wrote:
>
>> Another (at least theoretical) advantage of using pressure for
>> the gap is that the gap spark length is shorter in higher pressure
air
>> than in lower pressure air for a given voltage. Short sparks have
>> lower losses so a stronger spark output streamer length should
>> result. I'm not sure how much difference it makes in the
>> real world. I think Gary Lau used this approach when he
>> switched from his vacuum gap to his vortex gap. It's interesting
>> to note that whereas Gary obtained around 63" sparks from his
>> vacuum and vortex static gaps, he obtained around 80" or 90"
>> sparks using a sync rotary spark gap, using the same NST power
supply
>> transformer.
>>
>> I don't think all that much work and research has been done in
>> this area (high powered air blast quenching for Tesla coils), so
it's
>> worth
>> more experimentation.
>>
>> An useful approach might be to add an electronic trigger electrode
>> for stable 120 bps operation. This adds complexity, but not of
>> the mechanical machining type.
>>
>> John
>> ----------
>>
>>
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>>
>>
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