@sebosfato:
Thank you, quite good explained, this is what I meant. Much better explained than I did...
@All:
I think this is a nice theory you got there about the +-. But I think there's one major flaw in it, which actually IMHO shatters this theory: The WFC was made as a tubular array!
And as I said before, due to the "Faraday-cup"-effect this changes quite thoroughly what is happening in relation to a WFC which would just have 2 plates.
Explanation:
If you have a metal tube, then the water inside will always remain neutral no matter how you change the potential (voltage) of the tube in relation to this water. The water itself would always see a neutral tube from the inside. This is the "Faraday-cup"-effect.
An example for better understanding this effect:
You have a glass bowl, filled with water. Now you put an electrode in it. Up til now, everything is neutral (uncharged, equal pos and minus). Now you put, say a few thousand volts plus on the electrode. The water will immediately get charged (ionized) by this. Chemically, you will get an anode reaction: 3H20 - 2e -> 2H3O+ + O2 and if some OH- ions happen to be near the electrode 4OH- -4e -> 2H2O + O2
So now, you have more H3O+ ions in the water, than OH- ions. The water is not electrically neutral anymore.
Now you take instead of a glass bowl a metal bowl. And you directly use the metal of the bowl as an electrode. If you now put a few thousand volts plus on the electrode (bowl). Absolutely nothing will happen with the water. No reaction at all. For from the water point of view, the bowl always remains neutral, no matter what charge it has. It could have 100 million volts on it, from the water point of view it would look as if it's neutral. That's the "faraday-cup"-effect.
So from an electrostatic point of view, on which this theory relies, the outer tube is always seen as neutral by the water. At least from the inside of the tube. But as Stan heavily isolated the outside of the outer tube, the outer tube is not able to get any outside contact with the water. So with this information you can easily say, that any water in contact with the outer tube only sees this tube as electrostatically neutral (uncharged).