TR24-A3b Order phenomena in dusty plasmas

Project objectives

This project is focused on order phenomena in strongly coupled dusty plasmas, in particular the structure, confinement and dynamic properties of 3D-Coulomb balls, which are studied with complementary methods in subproject A3a at Greifswald University and in A3b at Kiel University. The long-term directions of research in A3b aim at understanding the competition of different ordering effects and the influence of magnetic fields.

Project leaders

Dr. D. Block
Prof. Dr. A. Piel

Approach

The investigation of structural and dynamic properties of 3D particle arangements is challenging, since it requires the simultaneous recording of all particle positions with good time resolution. In subproject A3b, the method of Digital Inline Holography (DIH) is applied to 3D Coulomb balls. This complements similar investigations with stereoscopic imaging with 3 cameras performed in A3a.

Experiment

The advanced diagnostic requirements for DIH demanded a complete redesign of the standard experimental setup (parallel plate discharge). The design and construction of a new discharge chamber finished in January 2006. The result is a fully symmetric stainless steel octagon. Inside its central circular drilling of 300mm diameter a heatable rf-electrode is mounted for plasma production. The octagon itself is grounded and acts as reference electrode. The top and bottom lids are equipped with numerous ports for vents, pumps and diagnostics. The full discharge chamber is mounted on a 3D translational stage and is placed in the central drilling of an optical desk, which carries all optical diagnostics.

Diagnostics

The experiment is equipped with two diagnostics to measure the 3D coordinates of particles in a dust cloud. The Scanning Video Microscope (SVM) and Digital Inline Holography (DIH) can be operated in parallel. The SVM is operative since March 2006 and the DIH setup was completed in August 2006.




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