Characterization of a Nanonewton-Sensitivity Counterbalanced Pendulum Thrust Stand for Pulsed Propulsion Systems

In this paper, we present the design, characterization, and calibration of a counterbalanced pendulum thrust stand suitable for ultrasensitive measurements of periodically pulsed thrusters. High thrust sensitivity is obtained by implementing optical heterodyne detection of the thrust stand displacement, which we show achieves sub-nanometer resolution. In addition, we exploit the high quality factor of the thrust stand mechanical resonance to amplify the displacement response by several orders of magnitude. As a test of the thrust stand’s high sensitivity, we perform a thrust calibration using light pressure generated by nine reflections of a continuous-wave laser with a power of less than 10 W. The calibration is performed at a resonant frequency of [Formula: see text] and a quality factor of [Formula: see text], although quality factors as high as 9215 have been measured. Using a modulated square wave forcing with a 50% duty cycle, we measure a sensitivity slope of [Formula: see text] and a detection limit of [Formula: see text]. To the authors’ knowledge, this is the first use of light pressure for counterbalanced pendulum thrust stand calibration and establishes a device sensitivity suitable for measuring modulated thrust levels in a variety of low-thrust applications.