Fig. 14
From: An in-flight plasma diagnostic package for spacecraft with electric propulsion
Configuration for testing of the two versions of the plasma sensor in a chamber with the HEMPT at Thales Deutschland GmbH. The RPAs of both sensors roughly point to the thruster exit (the sensors are labeled “DM” and “EM” for demonstrator and engineering model, respectively). The smaller but longer assembly of the thruster is the neutralizer. The drawings (a) and (b) show the same arrangement from different perspectives