The ejecta dynamics during plume-surface interaction

This study is aimed at understanding the physics of plume-surface interaction (PSI), a process in which a high-speed gas impinges on a bed of regolith, causing significant soil erosion and particle dispersal. The dispersed particles, often referred to as ejecta, can be accelerated to high speeds and expelled in all directions near the plume-impingement site. The expelled ejecta can also be entrained in the main flow field, changing the dynamics of the supersonic plume. To better understand the ejecta behavior, an experiment was conducted to track the velocity and acceleration of ejecta generated by a downward-facing jet impinging on a bed soil. A window on the soil bin allows for capturing both cratering and ejecta dynamics during the PSI process. Ultra-high-speed imaging systems on the order of 10 kHz to 1,000 kHz are used to capture ejecta motion. Ejecta statistics will be presented for both sea-level and vacuum conditions, various nozzle heights, and different particle material and size distribution.