A miniature force probe for cold gas thrust measurements

Area of Science:

• Aerospace Engineering
• Materials Science

Background:

• The growing space industry demands advanced electric propulsion systems.
• Conventional plume diagnostic tools lack versatility and cannot detect neutral species.
• Existing methods struggle with micro-Newton (μN) thrust range measurements.

Purpose of the Study:

• To develop and validate a miniature MEMS-based force probe for direct momentum flux measurement.
• To enable accurate thrust reconstruction in electric propulsion systems.
• To overcome limitations of conventional diagnostic tools, especially for cold gas thrusters.

Main Methods:

• Development of a miniature Micro-Electro-Mechanical System (MEMS) force probe.
• Calibration and validation of the force probe using a cold gas thruster.
• Direct measurement of total momentum flux and reconstruction of thrust.

Main Results:

• The MEMS force probe accurately measured thrust in the 200-950 μN range.
• Measurements showed good agreement (±5%) with a conventional thrust balance in the far field.
• Near-field measurements exhibited discrepancies up to ≈30%, attributed to pressure distribution and flow effects.

Conclusions:

• The MEMS force probe is a valid and versatile instrument for thrust measurements and plume diagnostics.
• It provides spatially resolved momentum flux data crucial for characterizing electric propulsion.
• The probe offers a significant advancement for testing next-generation spacecraft propulsion systems.