Re: Carbon rod electrodes?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "David Speck by way of Terry Fritz <teslalist-at-qwest-dot-net>" <dave-at-davidspeckmd-dot-org>

Rick
I tried this many years ago.  It gave a spectacular light show in the spark 
gap but torpedoed the TC output.

You want the spark gap to act as a high speed switch, preventing current 
flow until the main cap is fully charged, then releasing the stored charge 
suddenly to make the TC oscillate.

A carbon arc, because of the hot electrodes and residual carbon gas in the 
arc space will turn on at a very low voltage, preventing the tank cap from 
reaching a full charge, and thus limiting the TC output severely.  Previous 
posts have referred to degradation of TC output when the gaps get hot, even 
in gaps that use tungsten, which is not supposed to vaporize to any 
appreciable degree.

Therefor, you want a nice set of cold, well heat-sunk, non-vaporizing 
electrodes that will not break down 'till the cap is fully charged. Carbon 
electrodes won't work in this application.  Tungsten welding rods are 
probably the best readily available material for this purpose. Personally, 
I'd avoid the thoriated ones, as they may release trace amounts of 
radioactive dust in operation.  Plain tungsten or lanthanated tungsten rods 
are readily available, though.

HTH,
Dave

Tesla list wrote:

>Original poster: "Richard W. by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><potluck-at-xmission-dot-com>
>
>Hi list,
>I used to build arc lamps as a kid using the carbon rod salvaged from 
>carbon-zinc size D batteries. They were about the diameter of a pencil and 
>ran the full length of the battery. After some use the tips become conical 
>improving the gap.
>
>Anyway, could something like that be used in TSGs?
>
>Rick W.
>Salt Lake
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