Hall-effect thrusters (based on the discovery by Edwin Hall) are sometimes referred to as Hall thrusters or Hall-current thrusters. Hall-effect thrusters use a magnetic field to limit the electrons' axial motion and then use them to ionize propellant, efficiently accelerate the ions to produce thrust, and neutralize the ions in the plume.

The basic idea of Hall thrusters consists in generating a large local electric field in a plasma by using a transverse magnetic field to reduce the electron conductivity. This electric field can extract positive ions from the plasma and accelerate them to high velocity without extracting grids, providing the thrust.

How it works Electrons are generated by a hollow cathode (negative electrode) at the downstream end of the thruster. The anode (positive electrode) or "channel" is charged to a high potential by the thruster's power supply. The electrons are attracted to the channel walls and accelerate in the upstream direction.

A combination of electric and magnetic fields (Hall effect thruster) or an electrostatic (gridded ion) field then accelerates the ions and pushes them out of the thruster driving the spacecraft to tremendous speeds over time.

Hall thrusters were believed to be unable to compete because of the way they operate. The propellant, typically a noble gas like xenon, moves through a cylindrical channel where it is accelerated by a powerful electric field. It generates thrust in the forward direction as it departs out the back.