Plasma globes are
intriguing, and they may surprise anyone who has never
seen one before. This website explains the physics going
on inside a plasma globe that cause it to operate the
way it does.
The Device
A plasma globe is composed of a small Tesla coil (an electrode) surrounded by a large glass globe. This glass globe is sealed off, so the outside air can’t interact with the electrode at all and the pressure is both very low and constant. The air inside the globe also must have particular properties, which are described in the “Pressure and Gas” section.
http://www.physics.gla.ac.uk/~kskeldon/PubSci/exhibits/E6/
Physics 212
4/20/2014