Mie-Scattering Ellipsometry System for Analysis of Dust Formation Process in Large Plasma Device

We developed a new Mie-scattering ellipsometry system for the analysis of the generation and transport of dusts in large plasma devices, such as nuclear fusion experiment devices. The system is a rotating-compensator type and consists of polarizer and analyzer modules and a 2-D image sensor. A preliminary experiment was carried out using a small dust plasma cubic chamber. Spherical divinylbenzene polymer particles of 2.25 ± 0.05 μm in diameter with a dispersion degree of 0.1 μm were injected and suspended in an argon plasma. Light intensity data for 1600 pixels on each image taken 30 times per second were summed as a function of compensator azimuth angle, and then, ellipsometric parameters ψ and ψ were determined through Fourier analysis and relational equations. By the comparison of the determined ψ and Δ values with the calculated ones based on the Mie theory, it can be stated that they agree fairly well with each other and the measurement method is reliable.