Pulsed Complex Plasma in Microgravity

TL;DR

This paper introduces a pulsed plasma operation method that effectively eliminates voids in complex plasmas under microgravity, enabling the creation of large, homogeneous 3D dust clouds for fundamental research.

Contribution

The study presents a novel pulsed operation technique for plasma sustainment that achieves void closure in complex plasmas under microgravity, without altering particle behavior.

Findings

Void is completely closed with pulsed operation.

Particle cloud shape and density are unaffected by pulse period.

Method enables stable, large 3D complex plasma systems in microgravity.

Abstract

A new experimental method for creating void-free complex (``dusty'') plasmas under microgravity conditions is presented. The method is based on a pulsed operation mode of a four-channel radio-frequency generator for plasma sustainment. A dust cloud of micrometer-sized particles can be immersed in the bulk of a low temperature plasma under microgravity conditions. It typically contains a central volume depleted of particles - the void - that prevents the generation of large, continuous clouds. Experiments performed at different neutral gas pressures and discharge volumes during the microgravity phase of a parabolic flight show that the central void is closed completely once the pulsed operation mode is applied. The particle cloud shape, and the density distribution within the cloud, are practically independent on the pulse period within the investigated parameter range, and mainly depend on the overall discharge parameters neutral gas pressure and discharge volume. This indicates that the pulsed operation of the plasma source does not introduce new physical effects on the particles aside from the void closure. The proposed method has great potential for future application in experimental facilities dedicated to fundamental studies of large three-dimensional, homogeneous complex plasma systems in microgravity.