MICRO IMPULSE MEASUREMENT METHOD AND EXPERIMENTAL RESEARCH BASED ON TORSION PENDULUM

Satellite platforms with ultra-high microgravity levels play an important role in space gravitational wave detection and Earth’s gravitational field measurement. Pulsed micro-thrusters can help microgravity satellites achieve posture adjustment and control. The magnitude of the micro impulse is one of the important indicators to evaluate the propulsion performance of the pulsed micro thruster. There are two commonly used methods for measuring micro impulse based on torsion pendulum. The first method is to calculate the impulse based on the maximum angular displacement of the torsion pendulum after a single impulse element acts on the undamped torsion pendulum momentarily. The second method is to calculate the impulse based on the average angular displacement of the torsion pendulum rotation after the same high fixed frequency pulse is applied to the damped torsion pendulum. In order to realize the micro-impulse measurement of the pulse micro-thruster on the ground, the existing sub-micron-level thrust measurement system based on the torsion pendulum was used to conduct experimental research. We use the standard electrostatic force generated by the electrostatic comb to calibrate the existing torsion pendulum thrust measurement system, measure the torsion angular displacement through the capacitive displacement sensor, and obtain the relationship between thrust and angular displacement, as well as other torsion pendulum system parameters; Then, according to the two impulse measurement methods, the electromagnetic solenoid and the permanent magnet are used to generate the instantaneous magnetic force and the fixed frequency magnetic force to act on the torsion pendulum to study the micro impulse measurement capability of the thrust measurement system. The experimental results show that the impulse measurement range of the thrust measurement system is from 0.05 μN·s to 220 μN·s, and the impulse measurement resolution can reach 0.02 μN·s; Compared with method 1, using method 2 to measure micro-impulse can expand the impulse measurement range and improve the impulse resolution ability.