RF Helicon-based Plasma Thruster (IPT): Design, Set-up, and First Ignition.

To extend missions lifetime at very low altitudes, an efficient propulsion system is required to compensate for aerodynamic drag. One solution is Atmosphere-Breathing Electric Propulsion (ABEP). It collects atmospheric particles to be used as propellant for an electric thruster. The system ideally nullifies the requirement of onboard propellant storage. An ABEP system can be applied to any celestial body with atmosphere (Mars, Venus, Titan, etc.), enabling new mission at low altitude ranges for longer times. Challenging is operation of the thruster on reactive chemical species, such as atomic oxygen (AO), that is highly present in low Earth orbit, as they cause erosion of (not only) propulsion system components, i.e. acceleration grids, electrodes, neutralizers, and discharge channels of conventional EP systems. For this reason, a contactless plasma thruster is developed: the RF helicon-based plasma thruster (IPT). The paper describes the thruster design, implementation, and first ignition tests. The thruster presents a novel antenna called the birdcage antenna that is implemented for decades in magnetic resonance imaging (MRI) machines. The design is supported by the simulation tool XFdtd®. The IPT is aided by an externally applied static magnetic field that provides the boundary condition for the helicon wave formation within the plasma discharge. The antenna working principle allows to minimize losses in the electric circuit and provides, together with the applied magnetic field, acceleration of a quasi-neutral plasma plume.