Re: Thorated vs Pure Tungsten

Thoriated rods should have a more consistent firing characteristic, because
they are radioactive. Perhaps someone with more welding science background
could tell us why the thorium is added.  Thorium oxides are also refractory
and highly emissive (e.g. lantern mantles and old carbon arc electrodes
have thorium).

> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Thorated vs Pure Tungsten
> Date: Sunday, June 13, 1999 7:13 PM
> Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
> Hi All,
> 	I use 1/8 inch diameter thorated tungsten rods in my new neon protection
> circuit as safety gaps.  However, they tend to sporadically fire at low
> voltages.  The ends are cut pretty square instead of being rounded.  I
> replace the rods with the pure tungsten ones and grind them round on the
> ends.  However, I was just wondering if the thorium was mostly to blame
> the sporadic firing or the square ends?  This happens with nothing else
> connected except the neon running at full normal voltage.
> 	I really think, now, that the pure tungsten is by far the best for Tesla
> coil applications.  The slight radioactivity of the thorated versions is
> unsettling and this sporadic firing thing is a pest.  The tungsten rods
> seem to be far far better than anything else I have used and are
> the way to go for gap electrodes, as so many have found...
> Thanks,
> 	Terry