Wachs Benjamin N, Jorns Benjamin A
Department of Aerospace Engineering, University of Michigan, Ann Arbor, Michigan 49109, USA.
Rev Sci Instrum. 2022 Aug 1;93(8):083507. doi: 10.1063/5.0088831.
The design and performance of a thrust stand for characterizing low-power electric propulsion thrusters are presented. The thrust stand is capable of sub-millinewton resolution for devices on the order of 1 kg. The architecture is based on a counter-weighted hanging pendulum design, a variant of the standard hanging pendulum that employs a counterweight to increase force resolution. Thrust is measured in a displacement mode using the change in position of the pendulum arm as measured by an optical displacement sensor. Passive eddy-current damping is used to offset oscillations and decrease setting time. An in situ calibration rig using known masses is used to calculate thrust. The thrust stand features an adjustable counterweight for in-vacuum sensitivity adjustment. In addition, the design of a broadband (600-2490 MHz) wireless microwave power coupler is presented. The device eliminates stiffness and thermal drift introduced by coaxial cables-typically the leading source of error in testing low-power microwave and radio frequency-powered thrusters. The thrust stand and coupler were tested using an electron cyclotron resonance magnetic nozzle thruster operating with xenon at flow rates from 1 to 10 sccm and powers ranging from zero (cold gas thrust) to 40 W. The resulting measurements showed a force resolution of ∼10μN over a range of thrusts from ∼14 to 600 µN.
介绍了一种用于表征低功率电动推进器的推力台的设计与性能。该推力台能够对约1千克的装置实现亚毫牛顿分辨率。其架构基于配重悬挂摆设计，这是标准悬挂摆的一种变体，采用配重以提高力分辨率。推力通过位移模式测量，利用光学位移传感器测量摆臂位置的变化。采用无源涡流阻尼来抵消振荡并减少稳定时间。使用已知质量的原位校准装置来计算推力。该推力台具有可调节配重，用于真空环境下的灵敏度调整。此外，还介绍了一种宽带（600 - 2490 MHz）无线微波功率耦合器的设计。该装置消除了同轴电缆引入的刚度和热漂移，而同轴电缆通常是测试低功率微波和射频驱动推进器时误差的主要来源。使用电子回旋共振磁喷嘴推进器对推力台和耦合器进行了测试，该推进器以氙气为工作气体，流量范围为1至10 sccm，功率范围从零（冷气体推力）到40 W。所得测量结果表明，在约14至600 µN的推力范围内，力分辨率约为10μN。
