An interesting aspect of complex plasma is its ability to self-organize into a variety of structural configurations and undergo transitions between these states. A striking phenomenon is the isotropic-to-string transition observed in electrorheological complex plasma under the influence of a symmetric ion wake field. Such transitions have been investigated using the Plasma Kristall-4 (PK-4) microgravity laboratory on the International Space Station. Recent experiments and numerical simulations have shown that, under PK-4-relevant discharge conditions, the seemingly homogeneous direct current discharge column is highly inhomogeneous, with large axial electric field oscillations associated with ionization waves occurring on microsecond time scales. A multi-scale numerical model of the dust–plasma interactions is employed to investigate the role of the electric field in the charge of individual dust grains, the ion wake field and the order of string-like structures. Results are compared with those for dust strings formed in similar conditions in the PK-4 experiment.
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Liquid Plasma Crystals on the ISS
This study examines the structure and stability of filamentary dusty plasmas using data
from the Plasmakristall-4 (PK-4) facility on board the International Space Station. Under the
action of a polarity-switched DC electric field, the dust particles in the PK-4 discharge have
been found to organize into field-aligned extended filaments, which has been compared to the
filamentary state in electrorheological (ER) fluids. Here we discuss how, in addition to an
ER-type structural transition, the PK-4 dusty plasmas exhibit structural states reminiscent of
those observed in liquid crystals (LCs) with rod-shaped molecules. We find that dust particles
within the filaments are strongly coupled in a crystalline-like structure, while the coupling of
particles across filaments is liquid-like. In addition to a common orientation along a director
axis (nematic behavior), the dust filaments also appear to align in large-scale nested structures,
or shells (smectic behavior). Finally, these filaments are found to further arrange in hexagonal
patterns within the plane orthogonal to the director axis, suggesting the possibility for smectic-B
and smectic-C structural states. As the observed ER and LC features of the filamentary
dusty plasma states are sensitive to variations in the PK-4 discharge conditions, we argue that
these dusty plasmas can provide a controlled analogous system for the study of fundamental
phenomena in soft matter, such as the origins of pattern formation and universality of phase
transitions.
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- Award ID(s):
- 1903450
- PAR ID:
- 10469446
- Publisher / Repository:
- American Institute of Aeronautics and Astronautics
- Date Published:
- ISBN:
- 978-1-62410-699-6
- Subject(s) / Keyword(s):
- dusty plasma complex plasma self-organization liquid crystals
- Format(s):
- Medium: X
- Location:
- National Harbor, MD & Online
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.2514/6.2023-2615
