RE: [TCML] Large Plsma Tube

[Scott Bogard <teslas-intern@xxxxxxxxxxx>]

I order 12-in lighting globes from renovators supply warehouse for $9, 
http://www.rensup.com/globes/40004.htm
but depending on your patience level, it may not be worth the effort to build a sealing/discharge system.  I have been told you can order complete globes up to 36-in from corning glass, but you will pay a little more than $9!  And I can't find them on their website.  But if you did get one, all you would need to do is apply vacuum, add gas and seal.  Good luck, I'm sure others will provide useful insights as well.

Scott Bogard.

> Date: Sun, 2 Dec 2007 11:36:48 -0800
> From: btmeehan@xxxxxxxxx
> To: tesla@xxxxxxxxxx
> Subject: Re: [TCML] Large Plsma Tube
> CC: 
> 
> Where do you guys get the big globes from?  (or even medium or small sized
> globes)  Do you have to have a glass-blowing setup in order to really play
> with these things or do you just order pyrex chemistry glassware?
> 
> On Dec 1, 2007 7:35 AM, Bill Lemieux <gomezaddams@xxxxxxxxx> wrote:
> 
> > PS: I forgot to mention the end-seals.  Because the ends will probably
> > have to be flat, you should consider using 1/2" thick plate to span a
> > 6" distance.  This is a bit on the overkill side for 15PSI of
> > pressure, but better safe than sorry!  Make sure you don't introduce
> > any small cracks when you drill the plates for your electrodes, and
> > polish all edges to eliminate sharp edges or pits from drilling or
> > cutting.  Use fine emery paper for this.
> >
> > Forget about using plastics for your end plates, it won't last.  Among
> > other things, atmospheric helium and hydrogen will leak in (through
> > the material) over the passing years... possibly changing the
> > appearance of your discharge significantly. You're going to have
> > problems with that using epoxy seals anyway, but if the exposed area
> > of the epoxy seal is tiny and the thickness great (ie; .25") they
> > ought to be good for many years.
> > The higher pressure you can operate at, (approaching atmospheric) the
> > slower this leak problem will be.
> >
> > This is why old epoxy-sealed HeNe lasers died after about ten years -
> > the helium would diffuse out through the seals.  Amazingly, because
> > there was still a low pressure inside the tube, you could rejuvenate
> > those old tubes by sticking them in a bag of cheap balloon helium, and
> > operating the tube - you'd check it every few days and eventually it
> > would be working as good as new.  Take it out of the bag, and it would
> > once again be good for years.  Of course, with modern diode lasers and
> > even cheap hard-seall HeN lasers being so plentiful, that isn't worth
> > the effort.  Epoxy-sealed HeNe lasers are worthless now.
> >
> >  - "Gomez"
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