Spatter ejection associated with a SS316L powder layer (a,b) and for a SS316L plate (c,d) for two parameter cases: 150 W, 0.5 m/s and 200 W, 1.5 m/s. The camera frame rate was 100 kfps with an exposure time of 8 μs. Laser scanning is performed from left to right. Both cases are in an Ar environment. (e,f) Particle Image Velocimetry (PIV) was used to quantitatively measure projected velocities. Average velocities of >9 m/s are observed at the center of the plume for the 150 W, 0.5 m/s case and >7 m/s for the 200 W, 1.5 m/s case. Black arrows show actual particle path data and orange arrows are interpolated data. (g,h) Simulations showing regions above boiling in the melt pool depression for a bare plate. The arrows indicate the expected direction of the vapor plume.