Measurement of Plasma Formed by High-Speed Impact to Estimate Temperature at Impact Point

Structures in space are at the risk of collision with space debris, motivating the study of high-speed impact phenomena. In high-speed impacts, the temperature increases rapidly at the impact point, possibly causing destruction at the impact point in addition to impact pressure. However, the influence of high temperature has not been elucidated because existing thermometers do not have sufficient time resolution to measure the increasing temperature at the impact point. In this study, plasma formed by high-speed impact was measured and observed to estimate the temperature at the impact point. High-speed impact experiments were performed using a gas gun to form plasma. A projectile impactor and target were made of aluminum alloy, and the projectile velocity was approximately 650 m/s. High-speed images and high-speed optical visualization images of the state of plasma diffusion were acquired using a high-speed camera. In the experiments, the electron temperature of the plasma was measured by employing the triple probe method, and it was confirmed that high-speed optical visualization images are useful for observing plasma diffusion behavior.