Charged plasma and ion grid in interaction in ion thrusters

A good high power ion thruster uses a lot of energy to accelerate ions to high energies.

The image does not include any power source, which is a serious problem if a person looking at the image wants to understand how ion thrusters work.

A simple ion thruster woks like this:

A small amount of energy is used to ionize a bunch of atoms, then a much larger amount of energy is used to move some of the electrons away from the plasma. Now the plasma is a positively charged plasma, from which positive ions tend to fly off. If there's some negative object nearby, it accelerates the approaching positive charges and decelerates the positive charges that are moving away, so the negative object does not really do anything to the ions that move past it, but it may prevent ions flying off into the opposite direction.