Experimental study of the circular subsonic pipe jet expanding into near vacuum environment

In extreme ultraviolet (EUV) lithography, mitigation of tin (Sn) debris contamination during EUV light generation is an important issue. In practice, the high-speed jet flows are used to transport debris away from the collector mirror, thereby protecting it and improving system performance. Since EUV light is generated in a near-vacuum environment, understanding jet flow behavior in these extreme conditions is crucial for effective contamination control. In this study, we introduce a new facility designed to investigate jet extruded into near-vacuum environments using particle image velocimetry (PIV) and particle tracking velocimetry (PTV). Our results reveal a significantly extended potential core and a “top-hat” velocity profile with an inlet flow rate of 0.28 standard liter per minute (SLPM) and ambient pressure of 13.9 Pa. We also investigate the effects of inlet flow rate, ambient pressure, and jet diameter on the centerline streamwise velocity of the jet flow. These findings aim to guide the design of equipment operating in vacuum conditions.