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 nanoimpulse 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. Report Documentation PageForm Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.

Comparison of electrostatic fins with piezoelectric impact hammer techniques to extend impulse calibration range of a torsional thrust stand

“…As the impulse time approaches 1/10 th the period of the stand, the error rapidly increases as discovered earlier by D'Souza and Ketsdever. 9 A similar error trend for the PIH is displayed in Figure 14. At low impulses, the zero location and numerical integration error of the instantaneous force profile decreases accuracy.…”

Dynamic Measurements of Impulses Generated by the Separation of Adhered Bodies under Near-Zero Gravity Conditions

“…Precise measurement of small impulses performed by other authors [8][9][10][11] resulted critical, mainly for two reasons. Firstly, the force impulse needs to be entirely converted into momentum; therefore, any other force acting in the same direction on the body subjected to the impulse must be minimized.…”

“…The conversion of impulse into momentum may be guaranteed by a suspension system that minimizes the risk of any impulsive constraining force in the direction of the impulse to be measured. Suspension systems based on simple pendulum, linear rail and torsion pendulum [10,11] have been adopted to provide a weakly constrained axis. The presence of a single weakly constrained degree of freedom does not limit the measurement, as long as the impulsive force is a non-contact force and it is reasonably aligned with the "soft" axis.…”

“…The measurement accuracy is therefore limited by the superimposed noise to the swing-mode signal, mainly due to the ground micro-seismic activity and the readout system. Different techniques have been used in the literature to extract the applied impulse from the measured free oscillation of the suspended system [11]. In this paper, we adopted the standard Wiener-Kolmogorov Filter (WKF) theory of optimal estimation [7,12] to assess the momentum transferred by an impulsive force to a harmonic oscillator.…”

Electrokinetic pumping of liquid propellants for small satellite microthruster applications

“…10 shows the thrust measurement apparatus and exhaust plume visualization setup used to evaluate microthruster performance. While a variety of custom thrust measurement schemes have been employed to study small thrusters [34][35][36][37][38], we chose instead to adapt a precision laboratory balance (XP-205, MettlerToledo, Columbus, OH) to this purpose. This platform enabled thrust force measurements with a resolution of 0.1 N and an average data sampling rate of 8.6 Hz.…”