[dorkbotsea-blabber] tiny neon tube art?

[Bill Beaty]

At 03:52 PM 2/1/2005 -0800, you wrote:
>> but on the same vein, have you looked at making your own nixie tubes? The look
>
>you can -make- nixie tubes? do you have any documentation on this?


I wouldn't be surprised if you can make nixie tubes at one atmosphere (no
pump required.)

After all, you can make "plasma globes" at 1atm.   In 1995 some guy on one
of the Tesla Coil listservers mentioned that he worked for the company which
made the first batch of "eye of the storm" devices for Radio Shack.  He
said that the gas mixture was mostly helium...  and also mentioned that it
worked fine at one atmosphere, although the final product used a lower pressure.
After I ranted about using plastic bags and cardboard boxes with cellophane
windows, Ed Harris took up the challenge and actually tried some Helium at 
760torr with a flyback Tesla coil and found that it worked; it gave a dull
red plasma filament.  Then he found that welders' argon gave a brilliant
white filament discharge.

We played with this effect at several Weird Science meetings.  The argon
is slightly heavier than air (and is cold as it comes from the tank,) so
it pools at the bottom of flasks and aquariums.  Stick a high voltage supply
lead into a pool of argon, and long threads of brilliant white plasma spew
forth.  The plasma display won't penetrate into the air, so the top of the
plasma pool looks a bit like an invisible wall.   Note that even a tiny
bit of nitrogen will poison the effect (although an extremely tiny bit of
nitrogen will give the discharge a violet color.)

See:

Plasma globe at 1 atmosphere
http://amasci.com/tesla/heli1.html

Building plasma globes
http://amasci.com/tesla/plasplan.html


For nixie tubes you'd need neon.   It's a bit pricy at 1atm density.
I haven't experimented, but I would imagine that if you turned the 
drive voltage way down, an electrode would become covered with a 
glow, rather than launching out long plasma filaments.   Or, if your
HV high-freq supply always generates filaments, you can eliminate them
by converting the output into extremely short, extremely HV pulses, 
with 10mS or 20mS of dead time between.




((((((((((((((((((((((( (  (    (o)    )  ) )))))))))))))))))))))))
William J. Beaty              http://staff.washington.edu/wbeaty/
Research Engineer             UW Chem Dept,  Bagley Hall RM74
beaty at chem.washington.edu     Box 351700, Seattle, WA 98195-1700
ph:206-543-6195 fax:206-685-8665