What voltage is needed to ionize oxygen at the centre of this ball and would we hear any noise from thunder?

The outer ball is 10 metres in diameter (its surface is the Earth’s atmosphere) and a vacuum separates the outer ball from a 1 metre ball of atmospheric air which exists at atmospheric pressure. The oxygen should glow blue.
Electrons should flow from the outer ball surface to the inner ball.
This is a model for balls of light. which form quietly in Hessdalen Norway.
https://en.wikipedia.org/wiki/Hessdalen_lights
http://www.hessdalen.org/index_e.shtml