An electrostatic ion thruster generates propulsive thrust by ionizing a noble propellant gas (such as xenon) inside a discharge chamber and accelerating the resulting positive ions through electrostatic extraction grids. The screen grid and negative accelerator grid establish an intense electrostatic potential gradient that ejects ions at tens of kilometers per second. An external hollow cathode neutralizer injects electrons into the exiting exhaust plume to prevent spacecraft electrostatic charging.