Resonant operation of a micro-newton thrust stand

A computer automated technique suitable for evaluating micro pulsed plasma thruster (uPPT) performance has been constructed and validated in the micro-Newton (micro N) force range. A swinging gate pendulum architecture oscillates with an 3 second period. Force is applied resonantly with oscillation each half period. The calibration method utilizes an electromagnet to pick up and drop masses to apply a known force in the same resonant fashion as thruster operation. The resulting equilibrium amplitudes are linearly proportional to the applied force with an intercept near zero. Thrust measurements are insensitive to short term random vibrational noise because of the resonant operation and are insensitive to long term drift because the amplitude measurements are relative, rather than absolute.