It seems that I don't understand ionization as well as I should. I had thought
that all the ions between electrodes would feel the same electric field and
would be ionized simultaneously, much as all the electrons in a conductor
move together. Why don't they all ionize together? Ignoring end effects,
don't they all experience the same field? Am I overidealizing the problem.
On a new plug the end of the center electrode has sharp edges so I presume
the fields are strongest here and ionization occurs here first and propagates
across the gap. Am I getting close?
What about preferences for forming positive or negative ions? I had expected
that an electrostatic precipitator (used to remove dust from power plant
exhaust) would strip electrons from the dust forming positive ions, which would
then drift to negative plates. Instead, I am told it is the other way around.
Any body know why one way should be any better than the other.