Direct thrust and plume divergence measurements of the IFM Nano Thruster

Abstract The IFM Nano Thruster, which consists of a porous tungsten crown ion-emitter to provide thrust in the range of 10 µN to 1 mN at 2000–5000 s ISP, has been tested on a µN thrust balance that has previously been verified at the ESA Propulsion Laboratories. A comprehensive assessment of the thrust performance has been complemented by measurements of the plume divergence using a novel segmented collector setup that allows to assess the ion current distribution within a 2D-section of the plume in a high time resolution. From the plasma probe measurements, an upper bound of 0.93 for the thrust coefficient has been derived, while direct thrust measurements have shown a thrust coefficient between 0.8 and 0.9 over the entire thrust range. From the test results, a complete thruster performance map could be established linking emitter current and voltage with thrust and Isp.