Dual-stream gas targets for a point source of vacuum and extreme ultraviolet radiation supported by focused electromagnetic radiation.

The article focuses on the visualization and analysis of continuous two-stream gas targets designed for point sources of vacuum ultraviolet (VUV) and extreme ultraviolet (EUV) radiation, relevant to advanced lithography technologies. Using a Michelson interferometer, the spatial distribution of gas concentration in jets formed by injecting heavy inert gas (argon) through a central channel and lighter gas (helium) through a peripheral channel was measured, demonstrating that helium injection compresses and extends the argon jet, effectively moving the plasma breakdown region away from the nozzle. This approach aims to reduce nozzle erosion and improve plasma conditions for EUV generation, particularly at wavelengths around 11.2 nm using xenon plasma, which may offer higher radiation intensity and reduced optical contamination compared to traditional tin plasma sources. The study provides detailed experimental methods and phase shift analyses to quantify gas densities, supporting the potential for optimizing gas targets in EUV lithography and plasma generation with implications for future radiation sources including terahertz-frequency plasma excitation.