Active vibration suppression in a suspended Fabry-Pérot cavity.

Area of Science:

• Precision Measurement
• Optical Interferometry
• Mechanical Engineering

Background:

• The Nanobalance thrust stand utilizes in-vacuum Fabry-Pérot interferometers for high-sensitivity displacement measurements.
• Accurate measurement of microthruster (<1 mN) thrust and noise requires sub-nanometric displacement sensitivity.
• Beat motion in the suspended pendulum system, excited by ground noise, can compromise measurement accuracy.

Purpose of the Study:

• To implement active vibration suppression for a suspended Fabry-Pérot cavity within the Nanobalance thrust stand.
• To mitigate beat motion centered around the pendulum's natural frequency (10-14 Hz).
• To ensure vibration suppression does not interfere with the 2 Hz measurement bandwidth required for thrust determination.

Main Methods:

• Development and application of digital control strategies for active vibration suppression.
• Utilizing a dual-pendulum system (active and passive) with the Fabry-Pérot cavity.
• Experimental validation of the control system's effectiveness.

Main Results:

• Successful suppression of beat motion in the suspended Fabry-Pérot cavity.
• Demonstration of micronewton accuracy in microthruster thrust and noise measurements.
• Preservation of the measurement bandwidth essential for thrust evaluation.

Conclusions:

• Active vibration suppression is effective in enhancing the performance of the Nanobalance thrust stand.
• The developed control strategies enable precise measurement of space microthruster performance.
• The Nanobalance system shows promise for advanced space propulsion testing.