Re: [TCML] Large Plsma Tube

[Scott Bogard <teslas-intern@xxxxxxxxxxx>]

David
     I don't know too much about gas conductivities, but I think the 
other two cents I have may be of use to you.  Neon has the lowest 
conductivity of any pure gas, and produces a red color discharge.  I 
believe Argon is next, and that makes a purple or even orangish or blue 
discharge dependent on pressure.  You are going to need a pretty hefty 
power supply for a tube of that size, I would not recommend DC, as it 
may slowly damage the tube walls because of ion migration, and depending 
on your setup, I may not make much light.  I think for a tube so large a 
fly back transformer just won't cut it, I am sure your TC would do the 
job quite nicely, but the display will be loud and very frantic (and 
probably painful to touch).  Some problems you may run into involve 
evacuating the tube, filling with gas, and then sealing it.  You should 
not use any plastic as it may allow air molecules to leak through, only 
metal or glass.  Most epoxies will outgas and spoil the discharge, but 
after searching the net for a few years I've found one that doesn't, it 
is supposed to be good to 10^-6 torr, and the table top fusor people use 
it, so it should be good but I have not yet tested it (I cannot remember 
what it is called, only that it is made by Loctite, and it is sold as a 
general purpose epoxy.  I will check the box when I go home tomorrow and 
send the information to you).  Do not bother with silicone, except for 
short term testing.  My webpage for plasma colors should be very useful 
to you, it shows lots of pictures of whats out there as far as gas 
combos and what they look like. 
http://bogard.110mb.com/Plasmaglobecolors.htm
My other Plasma globe pages should be useful to you as well.  Mark Dunn 
can tell you where to get gases.  Best of luck, let us know how it goes.

Scott Bogard.

David N. Van Doren wrote:
> Hello All
>
> I have a large glass tube 6" o.d. with .25" walls and 5 feet long. ( from and old blueprint machine) And it's just begging to be made in to a large Plasma tube. Somewhere I saw a list of gasses and their conductivities and can't seem to find it. Does any body know where it might be? If any of you have any experience or info that might help with this project I'd greatly appreciate the boost in the learning curve. 
> I have several HV sources that I hope will be usable for this project such as an 85KV x-ray transformer or an 50 KVDC power supply and of course my Tesla coil ( an OBIT powered magnifier)
> This has the potential (sic) to be a very beautiful display.
>
> Thanks
> Dave 
> _______________________________________________
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>
>   


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