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How do I build a Glow Discharge Tube?

  1. Jun 22, 2011 #1
    Hello,

    I'm an undergraduate student, doing an independent research project under a professor this summer. So the experiment I am working on involves using a glow discharge tube, with electrodes at two ends, to create and contain a plasma column. The purpose is to measure and analyze "wave modes" of plasma oscillations (a type of MHD wave) coming from the plasma. Unfortunately, my physics department does not have a glow discharge tube for me to use, so I have to either build it or order it. I have had no experience with glow discharge tubes, so I'm not sure what the best way (the fastest way) to obtain it is. Any ideas would be greatly appreciated.. need to at least finish experimenting before fall term. The specifications (roughly) of the tube should be:

    38 cm long
    5.5 cm outer diameter
    5.15 cm inner diameter

    with:
    vacuum tubing (i guess for evacuating the tube) is: 3.8 cm diameter

    also:
    metal plate (allows the gas to flow thru, but defined the plane of the anode, instead of the vacuum tubing acting as the anode) is: 7.7 cm in diameter

    How would I go about making this in the shop (with the help with shop technicians)? Or should I order it from an equipment maker (if so, how much)?

    THANKS
     
  2. jcsd
  3. Jun 22, 2011 #2

    Drakkith

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    Have you tried google? I typed in glow discharge tube suppliers and saw several links on the first page that looked promising.
     
  4. Jun 23, 2011 #3
    Hello,

    So it turns out the Glow Discharge was not the problem. The problem is that my department won't allow me to use their vacuum system this summer, because of liabilities. I was wondering is there any way I can order one of these systems for less than $5000? that would be awesome if I can get a "clearance deal" on one of these babies

    THANKS
     
  5. Jun 23, 2011 #4

    jim hardy

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    2016 Award

    i get tired of insurance companies telling me what i can do.


    how much vacuum do you need? More correctly what absolute pressure?

    are you a tinkerer?

    refrigeration vacuum pumps will pull a fairly decent vacuum like 0.1 inch mercury absolute.. Places like harbor freight sell them cheap. Or you can jury rig the compressor from one of those little dorm fridges you see in dumpsters.

    if you need to make millitorr tell the professor he'll have to get more serious about helping you do the experiment.
     
  6. Jun 24, 2011 #5

    Drakkith

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    Are you wanting a vacuum system for under 5k, or the whole thing vacuum and discharge tube and all for under 5k?
     
  7. Jun 24, 2011 #6
    well, realistically I could pay for a vacuum system for under 2.5k, the department (shop) can provide the glow discharge tube

    otherwise, I will have to finish this experiment as part of my 4th year thesis project, early next school year
     
    Last edited: Jun 24, 2011
  8. Jun 24, 2011 #7

    Drakkith

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    So you want a vacuum system only then?
     
  9. Jun 24, 2011 #8
    yes, is that obtainable?
     
  10. Jun 24, 2011 #9

    Drakkith

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    I'm not sure. I guess it depends on how much of a vacuum you want. Do you know the required pressures you need to obtain?
     
  11. Jun 24, 2011 #10
    roughly 1 milli to 1 micro Torrs
     
  12. Jun 24, 2011 #11

    Drakkith

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    Alright. So you need just the pumps and connecting equipment? (Hoses, fittings, adapters, ETC?)
     
  13. Jun 24, 2011 #12
  14. Jun 24, 2011 #13

    Drakkith

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    I'm actually not anywhere close to an expert on vacuum systems, so forgive me if these questions seem a little dumb lol.

    What exactly is the "steel vacuum/pump system"?
    I'm assuming you need the foreline and turbo pump at minimum. I've been trying to build a Fusor for about 9 months now, so I had to look into this stuff a little bit. I purchased a used turbo pump and controller from ebay, but I have no idea if any of it works yet. You can get a foreline pump for a few hundred dollars, more or less depending on the flow rate you need. A new turbo pump is REALLY expensive though, and you probably don't need a turbo pump exactly, but any type of pump that will reach your required pressure. I think there are a few types of pumps other than turbo's that will work

    Since I don't know too much, all I can say is go to www.fusor.net, then go to the forums, to the Vacuum subforum, and look for some FAQ's on the vacuum systems. A search for "FAQ" in the vacuum forum would probably show them. A word of warning though, the forums over there REALLY suck with the layout and way it works lol.
     
  15. Jun 24, 2011 #14
    thanks, I will keep you up to date on any new developements
     
  16. Jun 25, 2011 #15
  17. Jun 25, 2011 #16

    Drakkith

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    I would think so, but you'd have to look at the numbers for everything. Sorry, I've bought a few items but I haven't even put them together yet lol
     
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