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Energy required to keep air in a plasma state

  1. May 20, 2005 #1
    Say that you are continuously creating plasma with some sort of sparking device. How strong of an electrical field is required to keep this air in its ionized state, compared to the field needed to ionize it initially?
     
    Last edited: May 20, 2005
  2. jcsd
  3. May 20, 2005 #2

    Astronuc

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    Staff: Mentor

    In creating the plasma in the first place, in the discharge (current of electrons), the electrons strike the atomic electrons knocking them out of the atom, if I may put it so crudely. However, the free electrons will slow by collision and will recombine with an ion.

    In order to maintain a plasma, one usually needs to maintain the discharge, or heat the plasma to the point where the collisions maintain a certain level of ionization. One the achieves a balance between ionization and recombination, which is a function of the discharge current or plasma temperature.

    As for using a static electric field, the electrons would drift to the positive electrode and ions to the negative electrode. The ions would then neutralize on the negative electrode.

    Now theoretically, one could put the air in a chamber, and ionize it in the presence of a static electric field. Presambly one would end up with + and - ions, e.g. O2+ and O2- or N2+ and N2-, however I am not sure about the stability of diatomic ions. Perhaps there is a some monatomic ions as well, and I believe triatomic O3, aka ozone, is possible. However, the presence of + and - ions is not the same as + ions and free electrons, which is the conventional meaning of a plasma.
     
  4. May 21, 2005 #3
    What if the electrodes had a non conductive sheild? You have one set of electrodes to create a spark to ionize the air, and a second set with the insulating coating that dont create current but just create a static electric field. Would the insulated electrodes hold the ions and electrons apart?
     
  5. May 21, 2005 #4
    You can make a type of plasma called ball lightning in your own microwave how ever they have not managed to keep it controled long enough to study it, if you wish to find out how exactly go to google and type in ball lightning, it is well worth doing
     
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