Recently, an increasing number of small satellites have chosen electric propulsion (EP) as the propulsion system for motion control in space flights. Research on the ejected high energy plasma plumes from EP thrusters has attracted significant interest due to their interactions with the components of satellites. This work demonstrates a probe array diagnostic platform (with 67 Faraday probes on the array) that enables the acquisition of the full three-dimensional morphology of the plume current density from the near-field to the far-field of EP stationary thrusters. The plume parameters of an ion thruster including the 3-D plume morphology, divergence angle, and thrust vector angle are measured using this diagnostic platform. From 250 to 700 mm from the thruster exit, the plume field exhibits a stable divergence angle of 43.6°. By fitting circles to the contours of each cut plane, the average thrust vector angle is calculated to be 1.3°, and the repeatability error for the circle center fitting is approximately 2.2%. The current density profiles on exit cut planes demonstrate an “elliptical distortion” phenomenon in the plume shape. Using the ellipse fitting method, it is found that an elliptical shape was formed in the near-field of the plume. As the plume propagates to the far-field, the distortion of the ellipse becomes more apparent (the aspect ratio is 1:1.14). Some possible causes may be the geo-magnetic field, background vacuum environment distribution, or thruster manufacturing error. The thrust vector data can provide a basis for the control strategy of the satellites. In addition, the 3-D plume current density data can give us a comprehensive understanding of the plume plasma physics. These results may also provide an accurate and rich database for parameters for future plume simulations.

近来，越来越多的小型卫星选择了电推进（EP）作为太空飞行运动控制的推进系统。由于EP推进器喷射的高能等离子体羽与卫星组件相互作用，因此引起了人们极大的兴趣。这项工作展示了一个探针阵列诊断平台（阵列上有67个法拉第探针），该平台能够获取从EP固定式推进器近场到远场的羽流密度的完整三维形态。使用此诊断平台可测量离子推进器的羽流参数，包括3-D羽流形态，发散角和推力矢量角。距推进器出口250至700 mm，羽流场表现出43.6°的稳定发散角。通过将圆拟合到每个切割平面的轮廓，平均推力矢量角计算为1.3°，圆心拟合的重复性误差约为2.2％。出口切割平面上的电流密度分布显示出羽状形状中的“椭圆形变形”现象。使用椭圆拟合法，发现在烟羽的近场中形成了椭圆形。当羽流传播到远场时，椭圆的扭曲变得更加明显（长宽比为1：1.14）。一些可能的原因可能是地磁场，背景真空环境分布或推进器制造错误。推力矢量数据可以为卫星的控制策略提供依据。此外，3-D羽流密度数据可以使我们对羽流等离子体物理学有一个全面的了解。这些结果还可以为将来的羽流模拟提供准确而丰富的参数数据库。