[TCML] High Power Static Gaps

[bartb]

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 at classictesla.com> wrote:
>
> From: bartb <bartb at classictesla.com>
> Subject: Re: [TCML] High Power Static Gaps
> To: "Tesla Coil Mailing List" <tesla at pupman.com>
> 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 at aol.com 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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