Development of a counterbalanced pendulum thrust stand for electric propulsion

We have designed and tested a thrust stand for RF plasma thrusters characterization. The balance is employed in the development of small and medium size RF plasma thrusters; it allows for a high number of tests per day with an accuracy in the order of 10%. The balance relies on the counterbalanced-type pendulum concept, which allows adjusting the instrument sensibility without changing the overall pendulum size. The range of thrust which can be evaluated depends on the mass of the prototype under test; e.g. for a 0.5 kg prototype the thrust can vary from 20 μN up to 50 mN. The system can be calibrated with both a calibration mass, and an electric calibrator. We have developed an algorithm which corrects the thermal drifts generated during thruster operation. We have compared the stand results against Faraday cup measurements, finding an agreement within 20%.