Helium Atomic Structure: Ionization Speed Compared to Air

[Sciencekid]

Would helium take less time to ionize than air, because it expand faster when heated up?

 

[Simon Bridge]

I'd expect some of the air to start to ionize before helium does but that Heluim will become a plasma sooner.
Look at the composition of air compared with helium gas, and the ionization energies.