New radio-frequency setup for studying large 2D complex plasma crystals

V Nosenko,S K Zhdanov,H M Thomas,J Meyer

doi:10.1063/1.5064457

Abstract

Complex plasma crystals are popular model systems where various plasma-specific or generic phenomena can be studied at the level of individual particles. Addressing the growing need for larger two-dimensional (2D) plasma crystals, a new plasma setup was built at the DLR Institute of Materials Physics in Space. The setup allows obtaining larger than before, highly ordered 2D plasma crystals and exploring new parameter ranges. It is based on a relatively large (90 cm in diameter) vacuum chamber where a capacitively coupled radio-frequency discharge is used to levitate polymer microparticles. The discharge is created between the lower rf electrode and the grounded chamber walls, the particles levitate in the plasma (pre)sheath above the electrode and are observed by video microscopy through the large top glass window and through the side windows. The first observations of plasma crystals in the new setup are reported.

Highlights

Complex, or dusty plasmas are suspensions of fine solid particles in a weakly ionized gas.[1]
We report on the new radio-frequency setup that has been built and is operational at the Deutsches Zentrum fur Luft- und Raumfahrt (DLR) Institute of Materials Physics in Space
Compared to the Gaseous Electronics Conference (GEC) rf reference cell,[25] the present setup is characterized by relatively high rf current and relatively low rf voltage. The latter may present an advantage in complex plasma experiments, since less sputtering of the particles and internal surfaces of the plasma chamber is expected for low discharge voltages

Summary

INTRODUCTION

Dusty plasmas are suspensions of fine solid particles in a weakly ionized gas.[1]. There is a growing body of evidence that many properties of complex plasmas, such as thermal conductivity and diffusion coefficient may be system-size dependent. We report on the new radio-frequency setup that has been built and is operational at the DLR Institute of Materials Physics in Space. It is based on a relatively large vacuum chamber (with the external diameter of 90 cm) and allows obtaining larger than before 2D complex plasma crystals.

Hardware solutions and data analysis method

Experimental parameters and plasma diagnostics

LARGE 2D COMPLEX PLASMA CRYSTALS

Wave modes of the plasma crystal

Mixed polarization without mode crossing

CONCLUSIONS AND OUTLOOK