Autowaves in a dc complex plasma confined behind a de Laval nozzle

TL;DR

This study investigates autowaves in a dense microparticle cloud within a dc plasma confined by a de Laval nozzle, revealing stable confinement, collective behaviors, and localized pulsed accelerations in the cloud.

Contribution

It demonstrates stable particle confinement behind a de Laval nozzle in a dc plasma and characterizes autowave patterns and collective interactions within the cloud.

Findings

Particles form a stable, confined cloud behind the nozzle.

The cloud exhibits inhomogeneous, tube-like convection structure.

Localized pulsed accelerations and wave patterns are observed.

Abstract

Experiments to explore stability conditions and topology of a dense microparticle cloud supported against gravity by a gas flow were carried out. By using a nozzle shaped glass insert within the glass tube of a dc discharge plasma chamber a weakly ionized gas flow through a de Laval nozzle was produced. The experiments were performed using neon gas at a pressure of 100 Pa and melamine-formaldehyde particles with a diameter of 3.43 {\mu}m. The capturing and stable global confining of the particles behind the nozzle in the plasma were demonstrated. The particles inside the cloud behaved as a single convection cell inhomogeneously structured along the nozzle axis in a tube-like manner. The pulsed acceleration localized in the very head of the cloud mediated by collective plasma-particle interactions and the resulting wave pattern were studied in detail.