EU-funded researchers developed and demonstrated a plasma propulsion engine that extracts and accelerates negative and positive ions to generate thrust. Applications include deep space propulsion as well as plasma accelerators and ion etching.
The main idea behind the EU-funded project NEPTUNE (New generation of ion sources: From deep space missions to upstream nano-technologies) was to accelerate ions and electrons extracted from a low-temperature plasma using a radio-frequency gridded system. This new concept can provide thrust without the need for additional current or charge neutralisation.
Further details: Plasma propulsion using new concepts