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An ion thruster is a type of electric propulsion that accelerates ions to produce thrust. It works by ionizing a propellant, typically a noble gas like xenon or krypton, and then using an electric field to accelerate these ions out of the thruster at high speeds. This expulsion of charged particles generates a force that propels the spacecraft in the opposite direction, according to Newton's third law of motion.

The core components of an ion thruster include a propellant source, an ionization chamber, and an accelerator system. In the ionization chamber, the propellant atoms are stripped of electrons, becoming positively charged ions. These ions are then drawn towards a set of charged grids or electrodes, which create a strong electric field. This field accelerates the ions to velocities significantly higher than those achievable with chemical rockets. As the ions are ejected, a separate source, often called a neutralizer, injects electrons into the ion beam. This neutralizes the charge of the exhaust plume, preventing the spacecraft from accumulating a negative charge that would otherwise attract the ions back and reduce thrust.

Ion thrusters are characterized by their very high specific impulse, meaning they are extremely fuel-efficient. While they produce very low thrust, which makes them unsuitable for rapid acceleration from rest or orbital maneuvers requiring high power, they can operate continuously for extended periods. This efficiency makes them ideal for long-duration missions, such as deep space exploration, satellite station-keeping, and orbit raising. The low thrust allows for precise control over spacecraft trajectory over time.