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Re: Spark gap metals

Original poster: "Steven Steele" <sbsteele@xxxxxxxxxxxxx>

I was mainly asking a question.
Wouldn't it be good simply to have a large surface area and a good fan as opposed to a small surface area?
that's all.

               Steven Steele
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, April 11, 2005 9:54 AM
Subject: Re: Spark gap metals

Original poster: "Harold Weiss" <hweiss@xxxxxxxxxx>

Hi Steven,

Malcolm's right there! On my newest 6" coil, just a few minutes of runtime started doing some damage to brand new thoriated tungsten points. (1/8") And that's only at the 12/120 power level. My older 6" coil has barely dented them at the same power.

David E Weiss

Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>

On 10 Apr 2005, at 15:17, Tesla list wrote:

> Original poster: "Steven Steele" <sbsteele@xxxxxxxxxxxxx>
> Why are ya'll so concerned about the metal your spark gaps are made
> of? As long as your the metal has enough surface area( to radiate
> heat) and you keep blowig air on it(like with a muffin man... I mean
> fan), it won't melt and it would be fine. You could even make a fine
> spark gap by replacing the copper pipes or tungsten rods with old heat
> sinks from scrap computers.Besides, isn't tungsten expensive? Trust
> me, I may be new at this, but I can tell you that fan cooled heat
> sinks or at least copper pipe(the longer the better) will do just as
> good, if not better, than tungsten rods. Also, the tungsten rods have
> less surface area than a copper pipe and therefore more likely to get
> really hot, and even though tungsten cand stand more heat, it doesn't
> need to as long as you cool it right. Tungsten rods are just a waste
> of money and tungsten.
>                     Steven Steele

        A word of advice: before you go telling others what's good
and bad it would be as well for you to know what you are talking
about. A gap works at the boiling point of the metal. Soft, low
melting point metals ablate and erode quickly. Who wants to be
rebuilding gaps after every coiling session? Some metals will produce
poisonous fumes when they evaporate (as they will with arc currents
of hundreds of Amps). I am not saying that copper is bad: simply that
your advice on the use of tungsten is not good. Tugsten electrodes
have been used in multi-kVA coils many times by some of the most
experienced coilers in the world.

      Cooling is not a simple matter of running a small fan or even a
large one. The gap material will spot heat far more quickly than a
fan can get rid of the heat. A number of people have suggested you go
and read information from various sources. With respect to Tesla
Coils, this list's archives contain an enormous amount of information
on every aspect of coiling and you would do well to start right there.