Specific signal imaging velocimetry for rarefied plasma flows

Abstract

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.