Development of a circumferential-scanning tomography system for the measurement of 3-D plume distribution of the spacecraft plasma thrusters

Plasma thruster—currently used on many spacecraft—is intensively developing to meet the new demands of space propulsion. The spatial distribution of the thruster plume is essential for thruster study. However, it is difficult to construct plume distribution due to the traditionally-used probe method's time-consuming point-by-point scanning procedure. In this work, a circumferential-scanning tomography (CST) system is developed as a powerful tool to characterize the plume distribution. The CST system is installed inside the vacuum chamber, rotates around the thruster, and takes plume images from different circumferential angles. The 3-D plume distribution is reconstructed using a filtered back-projection method from these images. The CST system is demonstrated on a plasma thruster. The thruster plume—twisting in three-dimensional space—is successfully reconstructed by the CST system. The reconstructed ion density of the plume is compared with a Faraday probe. The overall root mean square difference is ∼11 % along the trajectory.