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Re: materials of electroddes for Neon gas tubes..



Original poster: BunnyKiller <bunikllr@xxxxxxx>

in some of the most demanding enviroments (flashtubes for lasers, photography where insainly amounts of power are dissapaated in less than microseconds) tungsten is preferred...

Scot D



Tesla list wrote:

Original poster: d a <btoc3000@xxxxxxxxxxxx>

hey,

I thought the materials for electrodes used in any gas tubes should be of low sputtering energy materials?

what materials are best suited for the electrodes in a neon gas tubes/ gas discharge tube?

Thanks
sam

Tesla list <tesla@xxxxxxxxxx> wrote:
Original poster: William Beaty

On Sun, 2 Oct 2005, Tesla list wrote:

> Original poster: "Mercurus2000"
>
> I was just wondering, to make a neon light, all you really need is to
> pump a chamber down to several torr and then backfill fully till it's
> full with neon right?

I haven't done it myself, but I know that to make a professional neon sign
that lasts for more than hours, you need a thousands-watts HV transformer.
They're called "bombarders" in the industry. You can probably find info
about doing a home-built bombarder via one of the neon sign forum
archives. They're nasty expensive if bought new from a catalog.

You use the bombarder-transformer to run the neon sign at over 10x normal
output power while it contains low-pressure air, while also running your
pu mps. This heats the glass almost red hot, which drives out the water
vapor and adsorbed air, and which also anneals the glass joints so they
don't spontaneously crack over many days.

If you don't want to buy a bombarder, perhaps you could use a glassmaker's
annealing oven to do the same thing. With such an oven you could also do
all kinds of vacuum tube glassblowing, rather than just making neon signs.
Also, if you make Tesla coil driven neon art, I don't think a bombarder
will work. You'd have to outgass the weird glass shape in an annealing
oven while pumping it down. Or perhaps you can get away without the oven
if a huge "getter" can scavange up all the surface crap that slowly leaks
out into your low pressure environment.

I wonder if Radio Shack used annealing ovens on "Eye of the Storm" plasma
displays? If those displays use 1-atmosphere argon/helium/xenon mixture,
then perhaps the outgassing from the glass has little effect sin ce the
outgas volume is tiny when compared to the gas that's in the globe. That
would be another possibility: use 1-atmosphere nobel gasses in a neon
sign, rather than other types of gasses at millitorr pressure. Argon and
helium are cheap! Normal electrodes might be destroyed. I don't know.
But you could drive it with TC type supply, and wrap external electrodes
around the ends of the glass tube. That's basically how "Eye of the
Storm" is driven: the electrode is steel wool in a chamber open to the
atmosphere.


(((((((((((((((((( ( ( ( ( (O) ) ) ) ) ))))))))))))))))))) William J. Beaty SCIENCE HOBBYIST website billb at amasci com http://amasci.com EE/programmer/sci-exhibits amateur science, hobby projects, sci fair Seattle, WA 206-789-0775 unusual phenomena, tesla coils, weird sci