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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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