The Traceable Calibration of Thrust Stand by Electrostatic Force

Summary

Traceability calibration of mechanical characteristics of thrust stand is an essential prerequisite to ensure traceability measurement of thrust. Here, we describe how to calibrate the thrust stand by the electrostatic force generated by the parallel plate capacitor.

Abstract

Micro thrusters have important applications in low-frequency gravitational wave detection, satellite formation, and inter-satellite laser communication, so it is necessary to accurately measure the thrust of micro thrusters with traceability. A thrust stand is a widely used micro thrust measuring device with the advantages of high resolution and large load. Traceability calibration of mechanical characteristics of thrust stand is an essential prerequisite to ensure traceability measurement of thrust. In this study, a parallel plate capacitor was used to calibrate the thrust stand by generating a micronewton electrostatic force, which could be traced to the International System of Units (SI). The constant capacitance gradient range was obtained through simulation and theoretical calculation. Moreover, the electrostatic force could be changed by standard voltage with the advantages of simple principle, instantaneous trigger, and traceability. The device could be used for traceability calibration of micro newton thrust stand due to simple assembly and short traceability path.

Introduction

The micro thruster is indispensable for the ultra-static and ultra-stable space experimental platform to provide micro thrust to offset the non-conservative force on the spacecraft in real-time in low-frequency gravitational wave detection. Reliable measurement of the thrust of the micro thruster in the complex noise environment is the premise to achieve drag-free control. Therefore, it is essential to calibrate the thrust stand with high precision to establish the mechanical response model. The calibration methods of thrust stand mainly include two types, contact and non-contact calibration methods.

Contact calibration methods mainly inclu....

Protocol

1. Experimental realization

1. Gather all system components, including the circular parallel plate capacitor, the motorized linear stage, the thrust stand, the capacitance bridge, the SMU instrument, the laser interferometer, and other components, shown in Figure 1.
2. Fix Plate A on the motorized linear stage and fix Plate B on the arm of the thrust stand, making plates A and B parallel to each other.
   NOTE: The plates are processed by high precision grinding of aluminum alloy. The diameter of plate A is 6 cm, and the diameter of plate B is 4 cm so the alignment error can be ignored.
3. Contr....

Results

Following the protocol, the capacitance gradient and the stiffness of the thrust stand are calibrated. The principle of electrostatic force should be introduced. There will be relative motion D_ab between two charged plates under the action of external force F. Moreover, the work W by external force will be converted into electric energy E stored in the capacitor. The potential difference U, the charge of both plates Q and capacitance C can be obtai.......

Discussion

In this protocol, a parallel plate capacitor was used to calibrate the thrust stand by generating a micro-newton electrostatic force, which could be traced to SI. It is critical for all steps to calibrate the capacitance gradient precisely. The motorized linear stage made the initial plate spacing of this parallel plate capacitor equal to 1 mm and moved the plate A at a step of 0.02 mm. The capacitance bridge was used to measure the capacitance for accurately calibrating the capacitance gradient. The electrostatic force .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Motorized linear stage	Zolix	TSA50-C	Resolution 0.625 μm
Capacitance bridge	Andeen-Hagerling	AH2550A	Resolution 0.8 aF, Accuracy ±5 PPM
High voltage source measure unit (SMU) instrument	Keithley	2410	Precision 0.012%, ±5 μV– ±1100 V
Laser interferometer	Renishaw	RLE10	Resolution 10 nm
Circular parallel plate capacitor	Processed by high precision grinding		The plates are processed by high precision grinding of aluminum alloy. The diameter of plate A is 6 cm, and the diameter of plate B is 4 cm.
Thrust stand	Processed by high precision grinding		Pendulum type thrust stand