RE: [TCML] gaps

["Jim Mora" <wavetuner@xxxxxxxxx>]

Hi Bart,

No, I'm sorry I never scoped the gap. Consider the fresh vacuum cool air
flow created on the dowels created behind the air blast that is focused on
blowing out the hot ions at about 45 degrees up and back.

Jim

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of bartb
Sent: Tuesday, July 29, 2008 6:38 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] gaps

Hi Jim,

I have a question about your gap. The tapered air blast is focused 
directly into the gap between electrodes, but is there any airflow over 
the brass dowels themselves? It's interesting to me as it appears the 
air is being used to force quench the gap as opposed to just cooling it. 
I suppose the gap tips are being cooled, but if I'm understanding this 
gap air blast setup correctly, it appears the electrodes are staying 
cool due to quenching and not by "convection".

Have you scoped the gap to look at energy transfer waveforms 
(quenching)? I suspect it is quenching at the 1st primary notch. There 
are of course other aspects to consider such as actual power delivered 
to the gap, but your gap seems to give a ray of hope for solid stock 
electrodes. In my case, I attempted to cool solid brass round stock 
(1/2" x 3", several in a multi gap setup). They got hot quickly and 
performance dropped fast. The difference is that I was attempting to 
cool the brass stock itself. Due to the poor thermal cooling ability of 
solid stock, I failed even with a high air flow. I then tried larger 
brass stock (5/8" diameter). It took a little longer before sparks 
diminished, but I realized it was simply due to the fact that larger 
solid stock took a little longer to heat up at the same power level, but 
it eventually did, and air just would not balance out the heat at my 
power level. Then I decided to design for large surface area and fast 
heat up (which also cools fast, so balance and control is easier to 
obtain). Thus, large copper cylinders. The difference was amazing and 
confirmed with a 30 minute run! I was running probably higher power at 
180mA in all these attempts.

But, your gap is different in that it is blowing directly on the gap 
itself and "maybe" this is affecting quench times?

Regards,
Bart




> Jim Mora wrote:
>> Hi Bert,
>>
>> Please define big and power. My 15/120 used two 1" brass dowels 2" 
>> long each
>> spaced about .5" if I recall (end to end). They were threaded and 
>> therefore
>> easily adjustable. They would run 5-10 minutes and not get hot and 
>> cleaning
>> off the Zink oxide we have talked about was occasionally needed for best
>> performance. The faces were polished. And the air blast was very 
>> focused on
>> the gap and velocity enhanced by the fire hose like tapered nozzle 
>> which had
>> 2.5" input to .5" out tapered over 12" and set very close to the gap.
>
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