【作者】 杨元侠；

【导师】 罗俊； 涂良成；

【作者基本信息】 华中科技大学 ， 精密测量物理， 2012， 博士

【摘要】 随着人们对空间科学任务和实验的兴趣不断增加,现代空间任务对航天器的姿态和轨道控制、拖曳补偿以及变轨飞行等方面提出了更高的要求。作为提供飞行器动力的推进器,要求其提供的推力能够小到微牛顿量级。目前,科学家们研发了许多种类的微推进器以满足空间任务的需求。推力测量装置被广泛应用于推进器的推力性能地面测试,包括对推进器产生的单脉冲冲量和推力进行精确测量。因此,推力测量装置在推进器的研发过程中扮演了一个至关重要的作用。为了满足我国未来的空间科学任务需求,并结合实验室在精密扭秤上的丰富经验,我们发展了一种基于扭秤的推力测量技术用于测试微牛顿量级推进器的推力性能。通过特殊悬挂设计以及精密的扭秤结构组装,我们的测量装置不仅能够支持数公斤的推进器,而且在达到亚微牛顿的测量精度的同时,能够对推进器的单脉冲冲量进行开环测量,以及对平均推力进行开环和闭环测量。我们对测量系统的固有灵敏度和静态推力噪声分别进行了测量,固有灵敏度为6.3nN；在10-4到0.1Hz的频率范围内,推力噪声小于0.1μN/(?)Hz。为了确保我们测量结果的可信度,我们系统分析了各种误差源的影响,例如：真空环境的温度和气压波动、推进剂消耗、推进器导线引入的额外力矩,并对系统参数进行了修正。最终测量系统的单脉冲冲量测量范围可以达到1350μNs,分辨率为0.47μNs,平均推力测量范围可以达到264μN,分辨率为0.09μN,其测量精度只受到角度测量精度的限制。我们利用推力测量装置对中国科学院-空间科学与应用研究中心研发的脉冲等离子体推进器的原型样机进行了推力性能测试。单脉冲冲量的测量结果为(58.4±2.9)μNs,重复性为5%,在0.5Hz的工作频率下,平均推力的测量结果为(36.0±2.1)μN,稳定性6%；在1Hz频率下,平均推力为(62.6±2.3)μN,稳定性4%；在2Hz时,平均推力为(95.3±1.3)μN,稳定性1%。测量结果的误差比测量系统的精度要差一个量级,主要是由推进器的脉冲重复性不佳所造成的。另外,在我们核对了推进器的脉冲频率后,发现在高频部分,脉冲频率和平均推力不满足线性关系,原因是推进器在工作频率2Hz下的充电不够充分。根据对测量结果的分析,我们对推进器的进一步研究提出了一些改进意见。本工作得到了国家高技术研究发展计划(批准号：2008AA12A215)的资助。更多还原

【Abstract】 The increasing interests in space science missions and fundamental experiments re-quire the miscellaneous thrusters to provide extremely accurate thrust down to theμN-level for the attitude and position control, drag compensation, and de-orbit maneuver of the space-crafts. Recently, different types of the micro thrusters are being developed to meet the re-quirements of the space missions. In order to evaluate the performance of the thrusters in the ground test, the thrust stand is a universal and direct solution to measure the impulse bit per pulse and the thrust with the required precision, which plays a significant role in the development of the thrusters.In order to satisfy the requirements of further space science missions in our country, we develop a torsion-type thrust stand suitable for studies of micro-Newton thrusters, which is combined with the rich experience within the torsion-type tools in our laboratory. By virtue of specially suspending design and precise assembly of torsion balance configuration, the thrust stand not only has a load capacity up to several kilograms, but also is able to mea-sure the impulse bit in open loop mode and the average thrust in both open and close loop mode with a sub-micro-Newton accuracy. The inherent resolution of the thrust stand tested by gravitational source method is better than 6.3nN, and the sensitivity of static for-noise measurement is better than 0.1μN/(?) from 10-4 to 0.1Hz. We consider many possible systematic error sources to correct the parameters of the thrust stand to make sure our mea-surement results are convincing, such as the fluctuation of the vacuum temperature and the pressure, the propellant decrease, and the external torque provided by the thruster wires. The final thrust stand is capable of measuring the impulse bit up to 1350μNs with a resolu-tion of 0.47μNs, and the average thrust up to 264μN with a resolution of 0.09μN, which is limited by the accuracy of angular measurement.A pulsed plasma thruster, the preliminary prototype developed by Center for Space Science and Applied Research, Chinese Academy of Sciences, is tested by the thrust stand, and the results reveal that the average impulse bit per pulse is measured to be (58.4±2.9)μNs with a repeatability of about 5%, the average thrusts were (36.0±2.1)μN with a stability of 6% at 0.5Hz, (62.6±2.3)μN with a stability of 4% at 1Hz, and (95.3±1.3)μN with a stability of 1% at 2Hz, respectively. The accuracy of the measured results is about one order worse than the systematic uncertainty of the thrust stand, which is shows that the repeatability of the continual pulses is not well and dominant in the total error of the results, Besides, after checking the continual pulses frequencies of the thruster, we find the relation between the pulse frequency and the average thrust is not linearity at higher frequency, which indicates the discharge voltage is inadequate while the PPT working at the frequency of 2Hz. According to the analysis of the test results, we propose some improvement scheme for further thruster research.This work is supported by the National High Technology Research and Development Program of China under Grant No.2008AA12A215.更多还原