effect explanation

Ion thrust occuring during corona discharge due to interraction of ions with medium has following steps :

1) Ionization of air molecules near electrode with high field intensity near to it (the small electrode, the wire in the lifter). Lets call it "emitter" for simplicity.
2) Acceleration of ionized molecules by electric field in direction of wide electrode, let's call it "collector".
3) Transmission of momentum from accelerated molecules to outside air
Let's apply all this 3 steps to cases with different polarity. First lets make "emitter" positive.

1) We will have ionization of air to cathion-radicals or cations such as N2+ N2+*.
2) Positive particles will be accelerated in direction of negative electrode (collector)
3) Momentum is transmitted from accelerated positive particles in direction of collector.
Now lets reverse polarity and make "emitter" negative.

1) We will have ionization of air to anion-radicals or anions such as N2- N2-*.
2) Negative particles will be accelerated in direction of positive electrode (collector)
3) Momentum is transmitted from accelerated negative particles in direction of collector.