Ionthrust

Ionthrust refers to thrust produced by ion-based electric propulsion systems, a family of spacecraft propulsion methods that accelerate ions to generate momentum. Unlike chemical rockets, ionthrust relies on electrical energy to propel propellant, typically yielding very high specific impulse but relatively low thrust. It is suited for long-duration missions where efficiency and delta-v are prioritized over rapid acceleration.

The basic mechanism involves ionizing a propellant (often xenon), then accelerating the ions using electric fields created by grids or magnetic structures. A separate neutralizer emits electrons to prevent charge buildup on the spacecraft. The exhaust plume consists of fast ions and electrons, with the overall thrust depending on the ion current and the voltage applied.

Two major families dominate the field. Gridded electrostatic ion thrusters use a set of fine grids to accelerate positively charged ions, producing precise and steady thrust. Hall-effect thrusters use a combination of magnetic and electric fields to ionize and accelerate propellant within a quasi-neutral plasma, often delivering higher thrust at modest power levels. Both types share the characteristic high specific impulse, typically several thousand seconds, and low thrust that scales with available power.

Applications include deep-space missions, satellite station-keeping, and orbit-raising where long burn times and high efficiency are advantageous. The propulsion systems are powered by onboard solar arrays or nuclear power sources, making them unsuitable for atmospheric launch but effective for sustained propulsion in vacuum.

History and development began in the mid-20th century, with notable demonstrations aboard missions such as Deep Space 1 and the Dawn spacecraft. Ongoing research focuses on higher power systems, propellant alternatives, and increased reliability to expand use in future interplanetary exploration and commercial satellite service.