Fig. 7From: An in-flight plasma diagnostic package for spacecraft with electric propulsionRPA measurements at different plasma potentials in the HIBEX test chamber with the gridded ion source. The plasma potential is manipulated by means of the cathode (hot filament) bias voltage, (a) and (c) +10 V and (b) and (d) +35 V. The first row, (a) and (b), displays the raw RPA characteristics, and the second row, (c) and (d) the first derivative, representing the IEDFBack to article page