Re: [RE]Quenching Theory Question (fwd)

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Original poster: List moderator <mod1@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Fri, 18 May 2007 19:16:50 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: [RE]Quenching Theory Question (fwd)

Hi Matt,

Yes, voltage is "not" the only the determining factor. Bert and Jim gave 
"beautiful" reply's to this inquiry as they always do. Save those posts 
for reference in the future (I save every post I determine is gold). 
Everything the gap is made of, the geometry, the gas around the gap, the 
supply current and voltage at the gap all determine arc events. Material 
the electrodes are made from influence the arc. Material is blasted into 
the ionizing air and influences the arc channel. The current effects the 
gap resistance and the heated area of the arc channel.

The voltage is a good determination for a cold start as long as the 
material and electrode geometry is considered. But once the arc is 
formed, the gap air ionizes, it heats, it has a neutral to ionized 
recovery time depending on all those factors and external influence 
(such as fans). The barometric pressure that particular day even 
influences the breakdown voltage. Many things affect the gap initially 
firing as well as the time required before conduction across the gap 
stops. And then the electrode temperature, air temperature, gas 
ionization, and temperature effect the next breakout situation. Bert 
wisely mentioned the load. That in itself is a large factor for gap 
quenching.

Almost any info you find on spark gaps is always an empirical number 
meaning an experiment or/scientist has measured one particular number 
against another (voltage, electrode size, gap spacing are regular 
measurements for dielectric breakdown).

When considering spark gaps and list questions about them, I often refer 
to heat dissipation more than anything else because it is something we 
can control. For say a static gap, I refer to large surface area to 
dissipate heat. Granted, if there was enough moving air for say a 2 
electrode gap, fine, but there must be enough moving air to cool and 
stabilize the heat of a 2 gap setup. So, to deal with the air flow 
capability (the norm), adding surface area (electrodes) is needed and is 
why multigap spark gaps have been used for so long. All electrodes of 
course will have hot spots as determined by their geometry and position 
to each other. But the temperature of those hot spots can be greatly 
reduced simply by the number of gaps which increase the surface area and 
in turn, thermal dissipation. The biggest problem with several electrode 
cylinders is the air across them. If uneven, the gap will start out good 
but diminish quickly because a few of those electrodes are not being 
cooled like some of the others. Their re-arc voltage lowers, and it as 
if you decreased the gap spacing. If you can keep all the cylinders 
cooling concentrically, then you are on your way to a good gap. This is 
why the TCBOR/RQ gap is so endeared as probably the best static gap 
developed. It does give the ability to cool all cylinder electrodes 
evenly. But even with that, how you manage the air flow across those 
electrodes can also make a bad or good gap.

I probably shouldn't say this, but often I'll set my gap spacing a 
little larger to make up for the re-ignittion voltage rather than the 
initial breakdown voltage. Not a lot, just a wee bit more. I know that 
the reoccurring breakdowns will be at a slightly lower voltage, so I 
compensate a little. Ok, just to you let you know how much? When the 
tranny just does not fire with the gap (I set the gap and tranny alone 
by themselves, and increase the spacing until it just doesn't fire). 
Oops, there's one of my personal secrets. Some may see that as going too 
far. I think of it as an intervention due to physics.

Take care,
Bart

Tesla list wrote:

>Original poster: List moderator <mod1@xxxxxxxxxx>
>
>---------- Forwarded message ----------
>Date: Fri, 18 May 2007 18:42:39 -0400 (EDT)
>From: M G <gt4awd@xxxxxxxxx>
>To: Tesla list <tesla@xxxxxxxxxx>
>Subject: [RE]Quenching Theory Question (fwd)
>
>p {margin-top:0px;margin-bottom:0px;}
>I'm not an expert at any of this but I can say I looked at one of this
>list members websites. It showed one volt at one thousand amps jumping a
>large air gap just as one thousand volts at one amp would. So, I do not
>think the potential difference (voltage) is the only determining factor
>to spark length.
>Matt G.
>
>By the way, if the person with this website can link to that
>image/article that would be great.
>
>
>  
>