Principle of a positive corona discharge?

[Milchy]

Homework Statement

So as I understand, a negative Corona discharge happens between an electrode/pin/rod and a plane electrode. When the sharper electrode is connected to the negative (DC) plug, electrons concentrate on the tip, when sufficient breakthrough voltage is achieved a discharge happens and arcs to the plate electrode which is connected to the + DC outlet. - This scenario is perfectly understandable and imaginable.

Now... an article [1] tells me that there is a positive discharge when the sharper electrode is connected to the + and the plate el. to the -. It's visually showing me that the arc starts at the sharper(+) electrode, what I fail to understand is how its creating the arc? Positive ions shooting towards the negative plate? That can't be right can it? Is it gathering the charges from the atmosphere, attracting them, and once there's enough to fill the gap the ions use it as a bridge? But that can't possibly be true, the e- would just go down the electrode. So what is it I'm failing to understand here?

[1] CHANG, J-S. et al. Corona Discharge Processes. In IEE Transactions on Plasma science.1991. Vol 19, no. 6, p. 1152–1166

 

[andrevdh]

Corona discharge is a much more complicated mechanism in which the natural ions in the air are involved and increased by the electric field generated by the charge on the point. Look for instance on Wikipedia for more info.