Re: thoriated tungsten electrodes

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

I've been running pure tungsten for a few years now. They still look good.
I run over 10kva at
times, but infrequently. Most of the time it's in the garage at low power
levels. In any event,
the pure tungsten has been a winner in my book. Thanks to the Ed Wingate
for discussing his
experience with pure tungsten so long ago. I've never used the thoriated,
but others have used
it with success - but to what power levels I don't know. If power is high
enough, any material
will wear down. Thus, big coils use big electrodes. The gap gets very
expensive and changes in
complexity as power goes up.

Take care,
Bart

Tesla list wrote:

> Original poster: "Dave Leddon by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<leddon-at-attbi-dot-com>
>
> Interesting observation.  Thorium oxide is added to tungsten welding rods
> to improve arc initiation and to increase the arc stability, both
> undesirable conditions when trying to minimize the duration of the arc. So
> maybe plain tungsten might be the better choice for a rotary gap.  As to
> the hazards of thoriated tungsten rod, almost no release of radioactive
> material occurs during arcing, but real hazards exist during grinding as
> inhaled dust can cause long term damage.
>
> Dave
>
> At 11:33 AM 5/25/02 -0600, you wrote:
> >Original poster: "Mr Gregory Peters by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <s371034-at-student.uq.edu.au>
> >
> >Hello all,
> >
> >Regarding tungsten spark gap electrodes: Do thoriated electrodes work
> >noticeably better than regular tungsten? I'm just curious because my
> >11kV pig powered system chews up 4mm thoriated tungsten welding rod for
> >breakfast (no kidding). I don't need that radioactive dust floating
> >around. I think the reason my rods are eaten so quickly is because they
> >are quite long and can't conduct the heat away to the electrode supports
> >fast enough. I don't fancy rebuilding my RSG again however. I have been
> >reading some TIG welding brochures. Apparently, thoriated rods are best
> >for DC work and zirconiated rods are better for AC work. Wouldn't
> >zirconiated rods therefore be better for tesla coil work?
> >
> >Cheers,
> >
> >Greg Peters
> >Department of Earth Sciences,
> >University of Queensland, Australia
> >Phone: 0402 841 677
> >http://www.geocities-dot-com/gregjpeters
> >