Indium Liquid-Metal Ion Sources as Micronewton Thrusters

The Austrian Research Centre Seibersdorf has been engaged in the development of indium liquid metal ion sources for scientific space applications like spacecraft potential control and mass spectrometry for more than ten years. It holds the unique record of more than 900 hours of operations of this type of ion emitters in space borne instruments. Two operational instruments carrying indium emitters are currently in space and three more are being prepared for launch in the near future. During the last three years the focus of research activities has been targeted onto the development of a micronewton thruster using the already space proven indium emitters. Under a contract with ESA the basic physics of the indium ion sources as they are relevant for thrust generation and characterization have been studied and an engineering thruster model is currently being built. This paper aims at introducing the indium - FEEPs to the worldwide LISA community for the first time and to give an overview of recent activities and advances.