# Momentum when slow ion collides with fast electron?

Imagine high voltage alternating frequency glow discharge plasma between two plate electrodes with gas atoms inside.

There will be free electrons and positive ions.During first half of the sinewave one electrode is positive a the other one negative,then it reverses during second half of the sinewave cycle.

The result is that the positive ions and electrons are accelerated to one side,slowed down and accelerated to other side during each cycle of the sinewave,they bounce up and down.

My question is,what happens in terms of momentum when the positive ion collides with electron? Becose the electron is negatively charged,and the positive ion is positively charged,they will always be accelerated in opposite directions.

Positive ions are heavy and slow and electrons are light and fast,correct me if I am wrong but I assume that they will both acquire equal amount of energy from the electric field,its just that the positive ion is going to be moving much slower becose he have more mass,but their kinetic energy should be same if the electric field is equaly strong at both locations.

What happens when the positive ion collides head on with the electron if they are accelerated from stationary position by field of same strenght for same amount of time? Will they both stop? Or will the heavy slow ion continue with its speed and direction largely unchanged as if fly is splattered on the windshield of car moving on freeway?

Will they loose momentum at all? Will it be elastic or innelastic collision,or mix of both?

• Why wouldn't the ion absorb the electron? – A. C. A. C. Sep 8 '17 at 23:06
• I dont know,I am noob.I was thinking three things can happen,they collide and the electron enters the ion,the electron knocks even more electrons of the possitive ion,they collide but the electron wont get absorbed into the ion ( dont know if thats is possible ) but even if the electron gets united with the ion,will the new atom loose all its momentum? Will it stop in place? – wav scientist Sep 9 '17 at 0:32