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Re: Thorated vs Pure Tungsten
-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Tuesday, June 15, 1999 5:39 PM
Subject: RE: Thorated vs Pure Tungsten
>Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>
>
> Today I replaced the 2% thorium electrodes with pure tungsten. The gaps
>actually fired much sooner with pure tungsten?? However the firing voltage
>was more stable.
>
> I think the firing voltage depends mostly on the rather sharp edges I left
>on the rods. I will try to really round them out and see if that helps the
>stability. In retrospect, the sharp edges only make high field stress
>points. However, the thorium electrodes do seem to suffer much more from
>ionization caused by the radioactivity and thus like to sporadically fire
>far too early. I may end up using ball bearing electrodes to get a much
>more stable firing voltage for the safety gaps. I assume cobalt drill bits
>will cut through ball bearings to mount the shafts that hold them?...
You can get small solid metal balls with threaded holes in them quite
easily. look for any of the following: solid brass drawer pulls, lamp
finials (the ball on the top of the harp), etc.... They also make threaded
steel balls (and Alum too) for the knob on the end of machine tool handles.
McMaster Carr almost certainly has them, but so should a "machinery" dealer
(a place that sells real tools, like mills, lathes, etc.)
ball bearings are really, really hard, and because they are curved, it is
hard to drill a hole in them.
Any particular reason why you want steel?
>
> I definitely would stay away from thorium and other radioactive
>electrodes. Pure tungsten is supposed to wear faster but the worry of
>radioactive dust getting in one's lungs during the difficult cutting and
>grinding of this gnarly material out weighs that. "Playing" with the pure
>tungsten is far better than worrying about dust particles from the thorium,
>or cesium, or lanthanum... Some claim good wear from non radioactive
>alloys of tungsten too, but this is getting to be too complex as it is...
Cesium? I would expect cerium, a rare earth used in arc electrodes, flints,
etc. Cesium is like sodium, potassium, etc. soft, low melting point, very
very reactive..