Plasma Krystall-4 (PK-4) - 02.18.15
Plasma Krystall-4 (PK-4) is a scientific payload for performing research in the field of 'Complex Plasmas': low temperature gaseous mixtures composed of ionized gas, neutral gas and micron-sized particles. The micro-particles become highly charged in the plasma and interact strongly with each other, which can lead to a self-organized structure of the micro-particles: so-called plasma crystals. Experiments in the facility aim to study Transport Properties, Thermodynamics, Kinetics and Statistical Physics, and Non-linear waves and Instabilities in the plasmas. Science Results for Everyone
Information Pending Experiment Details
Sponsoring Space Agency
European Space Agency (ESA)
ISS Expedition Duration
September 2014 - Ongoing
Previous ISS Missions
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PK-4 is not an apparatus dedicated for specific experiments, but rather a laboratory which shall offer the possibility to perform a large variety of experiments with complex plasmas and to react to new developments in this field in a manner as flexible as possible.
The main interest lies in the investigation of the liquid phase and flow phenomena of complex plasmas.The experiments can be divided into three classes of fundamental questions:
- Microscopic properties of complex plasmas: charging of particles, external forces (e.g. ion drag), fundamental interactions, agglomeration, particle growth;
- Macroscopic properties of complex plasmas: hydrodynamics (e.g. viscosity), thermodynamics, non-equilibriums aspects of complex plasmas;
- Generic properties of classical many-body systems: Dynamic processes can be investigated on the level of single particles, which is not possible in most systems. Typical examples are crystallization and melting, photons in plasma crystals, dust waves, Mach cones, nozzles, turbulence, and nano-fluidics.
PK-4 is an experiment for investigating complex plasmas. Plasmas are ionized gases produced by high temperatures, like in the sun, or by electric fields, i.e., low temperature discharge plasmas like in neon tubes. In the latter case the degree of ionization is small and a large amount of neutral gas is present. Complex or dusty plasmas are plasmas which contain beside electrons, ions, and neutral gas in addition micro-particles, e.g., dust grains. Due to the strong influence of gravity on the micro-particles, most experiments on complex plasmas are strongly distorted or even impossible on earth and therefore require microgravity conditions. The main interest lies in the investigation of the liquid phase and flow phenomena of complex plasmas for which PK-4 is especially suited thanks to a DC-discharge and its geometry(elongated glass tube with a large observational access).
Plasmas are found throughout the universe, from the interstellar medium to the heat shields of spacecraft re-entering Earth's atmosphere. Understanding how plasma crystals form in microgravity could shed light on plasma phenomena in space, which could lead to new research methods or improved spacecraft designs.
PK-4 enables fundamental investigation of flows and related instabilities, by mimicking molecular mechanisms at a scale which allows for real time in-situ optical observations. This requires on-orbit experiments to be undertaken in order to observe the processes at work, which are obviously disturbed by the influence of gravity on Earth. Even though PK-4 is principally a fundamental experiment, understanding the processes at work and understanding how complex plasmas can be influenced by varying research parameters gives a better understanding of how improvements can be made in areas and industries where plasmas are used.
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Ground Based Results Publications
Takahashi K, Tonouchi M, Adachi S, Totsuji H. Study of cylindrical dusty plasmas in PK-4J; experiments. International Journal of Microgravity Science and Application. 2014; 31(2): 62-65.
Khrapak SA, Thoma MH, Chaudhuri M, Morfill GE, Zobnin AV, Usachev AD, Petrov OF, Fortov VE. Particle flows in a dc discharge in laboratory and microgravity conditions. Physical Review E. 2013 June; 87(6): 063109. DOI: 10.1103/PhysRevE.87.063109.
Goree JA, Liu B, Feng Y. Diagnostics for transport phenomena in strongly coupled dusty plasmas. Plasma Physics and Controlled Fusion. 2013; epub: 17 pp.