A gridded ion thruster uses electrical energy to create, accelerate and neutralize positively charged ions to generate thrust. The discharge chamber is responsible for the creation of ions when neutral atoms and electrons collide while the magnetic field containing the electrons increases ionization efficiency.
The screen and accelerator electrodes accelerate the ions to extremely high speeds using electric fields. The neutralizer provides additional electrons to balance the overall charge being ejected from the thruster and keep the spacecraft electrically neutral.
Learn more at go.nasa.gov/18IWxYY
NASA animation credit:
Eric S. Mindek (Wyle Information Systems, LLC)