Force probes for development and testing of different electric propulsion systems Alexander Spethmann, Thomas Trottenberg, Holger Kersten, Franz Georg Hey, Lou Grimaud, Stéphane Mazouffre, Daniel Bock and Martin Tajmar EPJ Techn Instrum, 9 1 (2022) 4 Published online: 07 June 2022 DOI: 10.1140/epjti/s40485-022-00079-w