A compound pendulum for thrust measurement of micro-Newton thruster

Area of Science:

• Aerospace Engineering
• Mechanical Engineering
• Physics

Background:

• Accurate measurement of micro-Newton level forces is critical for the development of advanced micropropulsion systems.
• Existing ground-based testing facilities often lack the sensitivity and precision required for micro-Newton thruster characterization.

Purpose of the Study:

• To develop and validate a novel thrust stand capable of measuring micro-Newton level forces with high precision.
• To characterize the performance of a micro-Newton colloid thruster using the developed thrust stand.

Main Methods:

• A compound pendulum thrust stand suspended by beryllium copper strips, calibrated by gravity, with adjustable stiffness.
• Utilized electrostatic actuation for calibrating the stand's resolution and determining equivalent thrust.
• Tested a micro-Newton colloid thruster, measuring thrust output variation with applied voltage.

Main Results:

• The thrust stand demonstrates a measurement range up to 1000 μN with noise below 0.1 μN/Hz (1 mHz-1 Hz).
• Achieved a calibrated resolution of 0.09 μN with a standard uncertainty of 0.02 μN.
• The micro-Newton colloid thruster exhibited a thrust output of 0.015(1) μN/V, with a 50 V change yielding 0.7 μN thrust (0.1 μN uncertainty).

Conclusions:

• The developed thrust stand is a precise and sensitive instrument for ground-based testing of micro-Newton thrusters.
• The stand's performance characteristics, including adjustable stiffness and low noise, are suitable for micropropulsion research.
• Validated the capability of the thrust stand by successfully characterizing a micro-Newton colloid thruster's performance.