High-velocity and rarefied plasma flow has found great application in aerospace science and technology. However, it is difficult to characterize such a flow using traditional methods based on the continuous medium flow hypothesis. With principles similar to those of particle imaging velocimetry, a specific signal imaging velocimetry method is proposed to measure the fluid velocity. Instead of using tracing particles, a specific signal was used as a fingerprint, which facilitated better fluid followability and measurement accuracy. As a verification example, the axial velocity distribution of a plasma plume along the flow direction was experimentally measured. The results agreed well with intrusive electrostatic probe measured values, which shows that SSIV has a great potential for fast and two-dimensional velocity measurements in similar flows. Considering the abilities and requirements of the experimental equipment and the signal processing techniques, the applicability of the proposed specific signal imaging velocimetry method was discussed.

中文翻译：

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稀薄等离子体流的特定信号成像测速仪

高速和稀薄的等离子体流在航空航天科学和技术中得到了广泛的应用。然而，使用基于连续介质流动假设的传统方法很难表征这种流动。利用类似于粒子成像测速的原理，提出了一种特定的信号成像测速方法来测量流体速度。不是使用追踪粒子，而是使用特定信号作为指纹，这有助于提高流体的可追踪性和测量精度。作为验证示例，实验测量了等离子体羽流沿流动方向的轴向速度分布。结果与侵入式静电探针测量值非常吻合，这表明SSIV在类似流动中的快速二维速度测量方面具有巨大潜力。