Plasma Krystall-4 (PK-4) - 01.27.16

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Plasma Krystall-4 (PK-4) is a scientific collaboration between the European Space Agency (ESA) and the Russian Federal Space Agency (Roscosmos), 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.
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Experiment Details

OpNom: Plasma Kristall-4

Principal Investigator(s)

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Gregor E. Morfill, Max Planck Institute for Extraterrestrial Physics, Garching, Germany
Vladimir I. Molotkov, Russian Academy of Sciences, Moscow, Russia
Laifa Boufendi, Universite d'Orleans, Orleans, France
Gerrit M. W. Kroesen, Eindhoven University of Technology, Eindhoven, Netherlands
Hubertus M. Thomas, Max Planck Institute for Extraterrestrial Physics, Garching, Germany
Andrey M. Lipaev, Institute for High Energy Densities, Moscow, Russia

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Sponsoring Space Agency
European Space Agency (ESA) and Russian Federal Space Agency (Roscosmos)

Sponsoring Organization
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Research Benefits
Scientific Discovery

ISS Expedition Duration 1
March 2015 - March 2017

Expeditions Assigned

Previous ISS Missions
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Experiment Description

Research Overview
Plasma Krystall-4 (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:

  1. Microscopic properties of complex plasmas: charging of particles, external forces (e.g. ion drag), fundamental interactions, agglomeration, particle growth;
  2. Macroscopic properties of complex plasmas: hydrodynamics (e.g. viscosity), thermodynamics, non-equilibriums aspects of complex plasmas;
  3. 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.


Plasma Krystall (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).

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Space Applications
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.

Earth Applications
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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Operational Requirements
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Operational Protocols
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Decadal Survey Recommendations

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Results/More Information

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Results Publications

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Ground Based Results Publications

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ISS Patents

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Related Publications

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Related Websites

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