Department of Science and Technology, University of Tsukuba, Tennodai, 305-0047 Tsukuba, Ibaraki, Japan.
Rev Sci Instrum. 2023 Mar 1;94(3):034501. doi: 10.1063/5.0087076.
Pendulum thrust stands are used to measure the thrust of electric propulsion systems for spacecraft. A thruster is mounted on a pendulum and operated, and the pendulum displacement due to thrust is measured. In this type of measurement, the pendulum is also affected by nonlinear tensions due to wiring and piping that deteriorate the accuracy of the measurement. This influence cannot be ignored in high power electric propulsion systems because complicated piping and thick wirings are required. Therefore, to reduce the influence of tension due to wires and tubes, we developed an inverted pendulum-type thrust stand with pipes and wirings as springs. In this paper, we first derive the design guidelines for spring-shaped wires; the necessary conditions for sensitivity, responsivity, spring shape, and electric wire were formulated. Next, a thrust stand was designed and fabricated based on these guidelines, and the performance of the stand was evaluated through calibration and thrust measurements using a 1 kW-class magneto-plasma-dynamics thruster. The sensitivity of the thrust stand was 17 mN/V, the normalized standard deviation of the variation of the measured values owing to the structure of the thrust stand was 1.8 × 10, and the thermal drift during the long-time operation was ∼4.5 × 10 mN/s.
摆式推力台用于测量航天器电推进系统的推力。将推进器安装在摆上进行操作，并测量由于推力引起的摆位移。在这种类型的测量中，由于布线和管道引起的非线性张力也会影响测量的准确性。在高功率电推进系统中，由于需要复杂的管道和粗电线，因此这种影响不容忽视。因此，为了减少电线和管子张力的影响，我们开发了一种带有管道和电线作为弹簧的倒摆式推力台。本文首先推导了弹簧状电线的设计准则；制定了灵敏度、响应度、弹簧形状和电线的必要条件。接下来，根据这些准则设计并制造了一个推力台，并通过使用 1kW 级磁等离子体动力学推进器进行校准和推力测量来评估该台的性能。推力台的灵敏度为 17mN/V，由于推力台结构引起的测量值变化的归一化标准偏差为 1.8×10，长时间运行期间的热漂移约为 4.5×10mN/s。
