Re: [TCML] Large Plsma Tube

[Yurtle Turtle <yurtle_t@xxxxxxxxx>]

I got two 10" globes from some online surplus store. I
don't remember which one.

Adam

--- Tim Meehan <btmeehan@xxxxxxxxx> wrote:

> 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"
> >  _______________________________________________
> > Tesla mailing list
> > Tesla@xxxxxxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
> >
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