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1. Liquid Plasma Crystals on the ISS

   https://doi.org/10.2514/6.2023-2615  

   Kostadinova, Evdokiya G.; Gehr, Emerson; Andrew, Bradley; Matthews, Lorin S.; Hyde, Truell W.; Terrell, Abbie (January 2023, American Institute of Aeronautics and Astronautics)

   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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2. ISS-GT/Prefix2Org: Dataset: 2025-04-01

   https://doi.org/10.5281/zenodo.17237945  

   Gouda, Deepak; Dainotti, Alberto; Testart, Cecilia (January 2025, Zenodo)

   No description provided. 

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3. COMPACT—a new complex plasma facility for the ISS

   https://doi.org/10.1088/1361-6587/ac9ff0  

   Knapek, C. A.; Couedel, L.; Dove, A.; Goree, J.; Konopka, U.; Melzer, A.; Ratynskaia, S.; Thoma, M. H.; Thomas, H. M. (November 2022, Plasma Physics and Controlled Fusion)

   Abstract Complex plasma is a state of soft matter where micrometer-sized particles are immersed in a weakly ionized gas. The particles acquire negative charges of the order of several thousand elementary charges in the plasma, and they can form gaseous, liquid and crystalline states. Direct optical observation of individual particles allows to study their dynamics on the kinetic level even in large many-particle systems. Gravity is the dominant force in ground-based experiments, restricting the research to vertically compressed, inhomogeneous clouds, or two-dimensional systems, and masking dynamical processes mediated by weaker forces. An environment with reduced gravity, such as provided on the International Space Station (ISS), is therefore essential to overcome this limitations. We will present the research goals for the next generation complex plasma facility COMPACT to be operated onboard the ISS. COMPACT is envisaged as an international multi-purpose and multi-user facility that gives access to the full three-dimensional kinetic properties of the particles. 

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4. ISS-GT/ru-RPKI-ready: Dataset: 2025-04-01

   https://doi.org/10.5281/zenodo.17237911  

   Gouda, Deepak; Fontugne, Romain; Testart, Cecilia (January 2025, Zenodo)
5. Numerical Modeling of the Plasmakristall-4 Experiment on the ISS

   https://doi.org/10.2514/6.2023-1587  

   Vermillion, Katrina; Terrell, Abbie; Gehr, Emerson; Kostadinova, Evdokiya G.; Hartmann, Peter; Matthews, Lorin S.; Hyde, Truell W. (January 2023, American Institute of Aeronautics and Astronautics)

   The microgravity environment of the Plasmakristall-4 experiment on the International Space Station provides a laboratory for exploring plasma-mediated interactions among charged dust grains in fully three-dimensional space. Away from the strong influence of Earth's gravity, the dust grains can levitate in the bulk of the plasma, where they have been observed to form extended filamentary structures aligned with the discharge tube axis. These structures can be used as a macroscopic analogue for other self-organizing systems, including electrorheological fluids and liquid crystals, and the success of the analogy depends on a thorough understanding of the mechanisms guiding the dust interaction potential. Here we present the results from molecular dynamics simulations of the ion flow past isolated dust chains within the dust cloud and the dust cloud macrostructure. Although dust grains are known to respond on the millisecond timescale, analysis reveals that periodic variations of plasma conditions on the microsecond timescale significantly affect dust structure formation. In addition to the expected formation of filamentary dust chains in the dust cloud macrostructure, dust grains in a large cloud are also observed to organize into ordered positions on the surface of nested cylinders, in agreement with experimental observations. 

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