Pulsed Plasma Thruster (Aerojet Rocketdyne)
The Pulsed Plasma Thruster (PPT) is a self-contained electric thruster system complete with inert solid propellant that provides very small thrust pulses for precise orbital positioning and pointing. The PPT requires only 1-100 watts of power, making it ideally suited to small spacecraft applications and attitude control.
Iridium Thruster : Advanced Systems 