[NewCandle] Vacuum, outgassing, etc.

[Nick Reiter]

Hi Kyle,

Quick reply here, since I am on a creaky laptop in former GDR at the moment:)

If you are not up for experimenting with graded glass to metal seals, you could do a couple of things - you could get some ready made lectrode seals at a neon sign shop, or you could use Torr-Seal which is a vacuum epoxy.  You can get that from Kurt J. Lesker Co.  KJL is the Radio Shack of vacuum - a bit pricier than some places but always there in a pinch.  Been using them for 25 years.

Tungsten, stainless steel, brass, aluminum, zirconium, molybdenum - good.  Zinc, cadmium, tin, lead - bad.  Copper is meh.

good luck with your Geisslers and Crookes!

nr
> All,
> 
> Anyone here with experience working with vacuum?
> 
> Questions:
> 
> 1. Anything good to seal (semi-permanently, should hold 0.1
> torr for at least a few months) metal to glass? I am no
> glassblower, so I'd prefer not to go down that route.
> 
> 2. What metals outgas the LEAST in this moderate vacuum
> environment?
> 
> I am capable of pulling a decent vacuum for making homebrew
> Crookes tubes, and have built quite a few. But I'd like
> to be able to seal it off from the pump, and have it
> standalone. I did this a short time ago (read: 1 hour) and
> the tube still works. Seal off was made by heating a glass
> tube epoxied to the side of the bottle where a hole was
> drilled. The tube softened and collapsed, at which point I
> used the flame end to narrow the dimple further, so I could
> snap it off. The tube, so far, holds vacuum and makes a nice
> electron beam.
> 
> Are there epoxies or other substances (what did they used
> back in Crookes' time??) to seal a 0.1 torr vacuum in?
> 
> The cathode is brass, the anode copper. I seem to remember
> reading that they were bad choices. Oops. What's good to
> use?
> 
> --Kyle
> 
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