A Low‐Noise Thrust Stand for Microthrusters with 25nN Resolution Available to Purchase

Accurate measurement of thrust from microthrusters is a significant technical challenge. We report significantly improved performance from our microthruster thrust stand which has now demonstrated 25nN thrust resolution and can carry a fully operational microthruster and power supply with up to 15kg total mass. Thrust capacity is 500μN with 0.5% accuracy and minimum response with 25% accuracy is 100nN. Because it is a critically‐damped torsion balance with tens‐of‐seconds response time, thrust readout noise is essentially absent for frequencies above 0.1 Hz. Other reported measurement techniques require careful leveling of the apparatus, or have higher readout noise, lower sensitivity and greater sensitivity to ambient mechanical vibrations. A key ingredient for the performance of our system design is an optical readout that responds only to rotation of the torsion bar, but not to ambient vibration. This feature eliminates sensitivity to footsteps, nearby vacuum pumps, etc. We will describe the design, calibration and testing of the optical readout.