Investigation of time-dependent forces on a nano-Newton-second impulse balance

Abstract

A torsional impulse balance has been developed as a new diagnostic tool to study fundamental physical processes in micropropulsion systems and laser–surface interactions. The impulse balance has been designed and tested with a robust calibration system to measure impulsive forces with resolution as low as several nano-Newton-seconds. The behavior of the impulse balance was thoroughly studied and characterized. A simple analytical model of the balance’s motion was developed from the general equation of motion of an underdamped, harmonically oscillating system. Also, two distinct methods of analyzing the experimental data from the nano-impulse balance have been investigated. The first method resolves the total impulse as a function of the balance’s maximum deflection. The second method enables the determination of the impulse and/or force applied as a function of time from the balance’s time-resolved motion. A calibration scheme employing electrostatic actuation techniques is used to experimentally validate the model and impulse measurement techniques.