Greifswald 2024 – scientific programme

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P: Fachverband Plasmaphysik

P 6: Poster I

P 6.30: Poster

Monday, February 26, 2024, 16:30–18:30, ELP 6: Foyer

Oxygen dependent size evolution of PMMA particles in the plasma sheath — Franziska Reiser, •Sören Wohlfahrt, and Dietmar Block — Kiel University, Kiel, Germany

Microparticles are the essential component of complex (dusty) plasmas. The forces affecting the particles, as well as their accumulated charge, depend prominently on their size. However, dependent on the particle material, the size and surface morphology of the particle will change when exposed to the plasma. Polymethymethacrylat (PMMA) particles show a strong plasma-particle interaction, resulting in a significant size reduction, or etching of the particle. In addition, a heavily modified surface structure with crests and trenches that has a reduced mass density of up to 50 % was reported. Compared to melamine formaldehyde (MF) particles, which show only a moderate response to the surrounding plasma, PMMA particles are an excellent research object to investigate the material dependent plasma-particle interaction itself, as well as the possible influence of the surface morphology on charging processes. An enhanced light scattering diagnostic based on Lorentz-Mie-theory is used to determine and track size and optical properties of the particle and thus the evolution of the plasma-particle interaction. The time resolved evolution of size and the optical properties of single PMMA particles for a systematic variation of oxygen admixture to the argon plasma are presented in this contribution. The results are compared to MF particles and complimented with levitation height measurements, which act as an indicator for particle charge.

Keywords: plasma-particle interaction; mie-scattering; PMMA-particles; levitation height