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Electrical Efficiency of Ionized Air?

  1. May 24, 2017 #1
    Alright It's been over a year since I've posted and received amazing help the last time I did. Now I've a question I cannot seem to find an answer to. Say you have an electrical charge and use a transformer to step up the voltage high enough to where it arcs in air. Then you have a conductive rod close enough to take that arc and then use a step down transformer to convert it to a usable voltage how efficient would this be? I've been racking my head about this and no matter where I look I can't find the answer and hope to find it here.
  2. jcsd
  3. May 24, 2017 #2
    Several manufacturers sell high-voltage anti-static gear that operates somewhat similarly. Simco comes to mind, but there are others.

    Efficient in what terms? Electrically, energy transfer through the arc is likely to be significantly inefficient.
    As opposed to other ways of creating free ions? I've no idea.

    3M once marketed a static eliminator consisting of small cylinder machined with 1/4" NPT female fittings on both sides with a sealed Polonium-210 source inside. Low volume compressed air was fed into one side, and ionized air came out the other. Ion-for-ion, I doubt they were cheaper to operate (compressed air is costly).
  4. May 24, 2017 #3


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    cbrown92 - I suggest you start by sketching a circuit diagram for us.
  5. May 24, 2017 #4
    If talking about an Arc that is generated by the electrical current, then all of the energy needed to create and maintain the arc ( heating and ionizing the air) will be "lost" and therefore in efficient, if you are talking about energy transfer to the 2nd transformer. Since most of the devices used to make an Arc are not made to transfer energy, their efficiency would me measured differently. Like a fluorescent light(an arc-plasma device - Efficiency would be electrical energy in vs light (energy) out.

    You can not transfer an electrical "charge" through a transformer - so som of you understanding on this may be a little off.
  6. May 24, 2017 #5


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    Perhaps consider a typical Neon discharge lamp? I think they strike at around 90V and require 70-80V to maintain the arc. Typical current is around 0.5 to 3mA.

    So the loss in the arc of the neon is about 75V * 2mA = 150mW
  7. May 24, 2017 #6
    Alright so from what everyone here has told me, transferring electrical energy through an arc is just a waste? I thought that might be different because when air is charged enough it's said to behave similar to metals. If that's the case wouldn't it behave similarly to something like aluminium in regards to its capability to carry an electrical charge? Like a wire, without the wire. Or does it not work like that?
  8. May 25, 2017 #7
    When searching for "resistance of electric arc" I found this pdf. It shows that strong, short sparks (with an energy of several tens of J) will cause you to loose less than 10% of the energy.
  9. May 25, 2017 #8
    So basically high energy arcs with very little distance in between does what I was thinking they would? Awesome! Reading the pdf as I type this. Im not sure if I'd have to post another question I have elsewhere but I will give it a shot here first.

    When building a unipolar dynamo from what I've read it generates really high amps/low volts.I also know that if you spin it counter clockwise the charge flows towards the center instead of outwards towards the edges of the disk. Even though this will generate a negative voltage I'm not too concerned about that.

    My next question is, what if I were to have a disk shaped coil winding around an iron or steel shaft? Being that the charge flows towards the center, would it step up the voltage automatically? If so, you could you get it high enough to arc that arc then transfers the charge to the component you want to power next to the spinning shaft?

    My thinking is if it generates enough voltage, it will arc, if it does this, AND i can direct it to the component I wish to power? I could transfer this energy without brushes, and save me on replacing them. That AND I wouldn't have to contend with frictional losses to the dynamo from the brushes touching them in the first place.

    Would this work?

    P.S. Thanks to everyone replying, you guys are damn well awesome.
  10. May 25, 2017 #9
    Wait - you want to send direct current through a transformer? You would need to pulse it or use a semiconductor based approach like e.g. a switching mode power supply.
    But you can't use a coil in a unipolar generator. Why not use a brushless AC generator, also known as an alternator?
    Or maybe tell us what exactly you need this for? There is probably a simpler solution.
  11. May 25, 2017 #10
    Why cant you use a coil-disk in a unipolar dynamo? I guess Im trying to think of a way to combine this concept with a tesla turbine. Where you have a magnets on either side on the outer casing of the turbine, and the copper disks inside and attached to a steel shaft. Tesla turbines are notorious for not having any torque. I know this sort of idea might generate a ton of eddy currents, but I also think it could work.
  12. May 27, 2017 #11


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    Actually, there is an 'arc' in a mercury arc rectifier and they are used for transferring vast amounts of power efficiently. So don't write them off. It just depends on what you actually want to do with your arc. (What is the purposed of your voyage Mr Noah? :-p)
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