Electrodeless electric propulsion is an advanced electric propulsion concept currently in the early stages of development. Some key advantages over conventional electric propulsion systems are the ability to scale to high power levels, and the separation of electrical components from the highly-energetic propellant flow. This separation increases longevity and enables the use of reactive propellants, permitting In-Situ Resource Utilisation (ISRU) and Air Breathing Electric Propulsion (ABEP), both of which constitute new capabilities for space flight. One electrodeless electric propulsion technology currently under active development from several groups worldwide is the inductive plasma generator (IPG). An IPG deposits power into a propellant flow via an induced azimuthal current and primarily produces thrust through gas-dynamic expansion.

IPG7 is an experimental IPG developed at the Institute of Space Systems in Stuttgart, Germany. IPG7 has demonstrated stable operation with non-conventional propellants such as O2 and CO2; however, its performance is difficult to characterise due to the complex interaction between the inductive coil and the plasma flow, and the intrusive nature of conventional experimental techniques. The work presented here aims to bridge the gap between the ‘microscopic’ behaviour (e.g. transient current and light emission measurements) and the ‘macroscopic’ behaviour (e.g. thrust and thrust efficiency) with the goal of understanding the different operating modes of the device and leading to optimised designs and controllability.