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Capacitor plates and tunneling current

  1. Jan 9, 2005 #1
    If two capacitor plates at a moderate voltage (200-300V) and low capacitance are kept very close to each other would there exist a tunneling current between them.

    If the tunneling current will exist, then it will gradually reduce the energy of the capacitor. Where will the used capacitor energy go?

    BTW, is there a limit to how much energy density a capacitor can have?
  2. jcsd
  3. Jan 9, 2005 #2


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    Yes, a tunneling current will exist -- ain't no infinite barriers around.

    Yes, the tunneling current will deplete the energy, but at something like an erg/century energy flow. The depletion comes from radiation. Note, you might generate more current by waving the capacitor in the air, at a fairly vigorous pace.

    Yes, when the plates begin to melt, or, when hit you dialectric breakdown -- the electric field begins to tear the dipoles apart. You can read about this in most any basic physics text.

    Reilly Atkinson
  4. Jan 10, 2005 #3
    Thank you. :smile:

    And for the breakdown part, I was actually talking about no dielectrics i.e. capacitor in vacuum.
    Under extreme voltages like million or billion volts and low capacitance, without dielectrics, will the electrons be able to break through the vacuum and travel to the positive capacitor plate even when the capacitor plates are sufficiently apart for no tunneling current to take place?
    Last edited: Jan 10, 2005
  5. Jan 10, 2005 #4
    Can anyone please answer my last question?
  6. Jan 10, 2005 #5


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    Just a guess. The tunneling current may be much like a thermally generated current, or, perhaps even more likely, that the tunneling effect produces an osmotic cuurent -- perhaps in both directions, not dissimilar to the ionic currents in neurons.

    I also suspect that it might be possible to build a simple QM model with potential wells to test and examine tunnelling currents in a capacitor.

    Reilly Atkinson
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