ARTICLES

Ion thrusters for electric propulsion – scientific issues developing a niche technology into a game changer

K.Holste,1, a) P.Dietz,1 S.Scharmann,1 K.Keil,1 T.Henning,1 D.Zschätzsch,1 M.Reitemeyer,1 B.Nauschütt,1 F.Kiefer,1 F.Kunze,1 J.Zorn,1 C.Heiliger,2 N.Joshi,2 U.Probst,3 R.Thüringer,3 C.Volkmar,3 D.Packan,4 S.Peterschmitt,4 K.-T.Brinkmann,5 H.-G.Zaunick,5 M.H.Thoma,1 M.Kretschmer,1 H.J.Leiter,1 S.Schippers,1 K.Hannemann,1, 6 and P.J.Klar1

1) Institute of Experimental Physics I, Justus Liebig University, Heinrich-Buff-Ring 16, 35392 Giessen, Germany

2) Institute of Theoretical Physics, Justus Liebig University, Heinrich-Buff-Ring 16, 35392 Giessen, Germany

3) Department of Electrical Engineering, University of Applied Sciences, Wiesenstr. 14, 35390 Giessen, Germany

4) ONERA, Palaiseau 91120, France

5) Institute of Experimental Physics II, Justus Liebig University, Heinrich-Buff-Ring 16, 35392 Giessen, Germany

6) German Aerospace Center, Institute of Aerodynamics and Flow Technology, Spacecraft Department, Bunsenstrasse 10, 37073 Goettingen, Germany

Abstract:
The transition from OLD SPACE to NEW SPACE along with increasing commercialization has a major impact on space flight in general and on electric propulsion by ion thrusters in particular. Ion thrusters are nowadays used as primary propulsion systems in space. The article describes how these changes related to NEW SPACE affect various aspects that are important for the development of electric propulsion systems. Starting with a historical overview of the development of space flight and of the technology of electric propulsion systems, a number of important missions with EP and the underlying technologies are presented. The focus of our discussion is the technology of the radio frequency ion thruster as a prominent member of the gridded ion engine family. Based on this discussion, we give an overview of important research topics such as the search for alternative propellants, the development of reliable neutralizer concepts based on novel insert materials as well as promising neutralizer-free propulsion concepts. In addition, aspects of thruster modeling and requirements for test facilities are discussed. Furthermore, we address aspects of space electronics with regard to the development of highly efficient electronic components as well as aspects of electromagnetic compatibility and radiation hardness. The article concludes with a resentation of the interaction of electric propulsion systems with the spacecraft.