  Electrical space thrusters show important advantages for applications in
outer space compared to chemical thrusters, as they allow a longer mission
lifetime with lower weight and propellant consumption. Mature technologies on
the market today accelerate positive ions to generate thrust. The ion beam is
neutralized by electrons downstream, and this need for an additional
neutralization system has some drawbacks related to stability, lifetime and
total weight and power consumption. Many new concepts, to get rid of the
neutralizer, have been proposed, and the PEGASES ion-ion thruster is one of
them. This new thruster concept aims at accelerating both positive and negative
ions to generate thrust, such that additional neutralization is redundant. This
chapter gives an overview of the concept of electric propulsion and the state
of the development of this new ion-ion thruster.

Accelerator Physics;Plasma Physics