Plasma crystals are a new kind of matter, rediscovered in 1994. They form under certain conditions in a complex (dusty) plasma. There, the electrically charged dust particles arrange in a regular macroscopic crystal lattice. This structure allows for an investigation of the properties of condensed matter on the kinetic level. This means that basic processes, such as melting, can be followed by observing the motion of individual particles. PK-3 will give investigators a better understanding of plasma in space and will determine the critical points for the plasma.Principal Investigator(s)
Max Planck Institute for Extraterrestrial Physics, Garching, , Germany
Kayser Threde, Munich, , Germany
European Space Agency (ESA)Sponsoring Organization
Information PendingISS Expedition Duration:
April 2006 - April 2007
13,14Previous ISS Missions
The PKE Nefedov mission was a less sophisticated version of this mission, studying complex plasmas in space from 2001 to 2005. The PK-3 mission has a new and improved design, based on drawbacks noted in the first experiment.
PK-3 Plus is a symmetrical driven radio-frequency plasma discharge with special features for the investigation of complex plasmas under microgravity conditions. As a second generation laboratory, PK-3 Plus provides major new possibilities for these investigations due to its design improvements relative to the first long-term experiment PKE-Nefedov. The PK-3 Plus apparatus allows investigations at neutral gas pressures between 0.05 - 2.5 millibar and radio frequency (rf) power of 0.01 - 1 W. The complex plasma can consist of monodisperse particles in a size range from 1 - 20 micrometers. Up to six particle sizes can be added to the experimental volume. It is possible to change the number of particles, the composition of particles, the plasma conditions and the neutral gas pressure during one experiment. The particle cloud can be excited by an electrical low frequency signal on the electrodes (0.1 - 100 Hz at a maximum amplitude of 50 V) or by a low frequency modulation of the rf-amplitude in different wave forms (sinusoidal, square, pulse, etc.).
The PK-3 investigation has two major pieces of equipment: the experimental block or plasma chamber, and the telescience system (TS). The research will be performed on the ISS inside the plasma chamber. The chamber is attached via a tube to the space environment to produce the vacuum conditions needed. The chamber can produce pressures less than 10-5 millibar.
The TS is the computer in which the chamber conditions can be altered and the storage unit for the data collected. This chamber will have state of the art hardware and software, and will provide better diagnostics than previous hardware. The chamber has an automatic mode, which will be run twice, measuring such parameters as particle size, gases present, pressures, densities, and plasma power. The third and final time the equipment is run will be an attempt to find different critical points. In this run, the plasma will be manually controlled by the cosmonaut to first be homogeneously distributed, then to be in a liquid phase, and then to have different particle densities predetermined by the investigators.
Learning more about the space environment will help us to better explore it. We can work safer, understand better, and ultimately travel further if we know more about the plasmas of space.Earth Applications
Plasma studies in outer space could provide answers to our questions about terrestrial plasmas such as lightning.
The experiment will have 3 or more runs (sessions) to meet the requirements of the investigator. There are two modes, automatic and manual, for this investigation. During the manual mode, crew time will be required to complete the investigation. The chamber records the parameters necessary to achieve the critical points, which will be sent back to Earth. Also to be returned are the videos of the chamber from its cameras, and the data recorded onto the TS hard disks.Operational Protocols
On three consecutive days, the experiment will be run. The first two days will be on automatic, as mentioned above, and the last day will be manual operations. On automatic days, the machine can be left alone to run, passively taking measurements of the plasma behaviors in microspace. On the manual day, there will be a cosmonaut present, adjusting settings to achieve the required states of the plasma. The experiment is expected to take approximately 90 minutes each day.
Thomas HM., Morfill GE. The Physics of Complex Plasmas and the Microgravity Programme on Plasma Crystal (PK) Research. 55th International Astronautical Congress, Vancouver, Canada; 2004
Samsonov D, Zhdanov SK, Quinn RA, Popel SI, Morfill GE. Shock Melting of a Two-Dimensional Complex (Dusty) Plasma. Physical Review Letters. 2004; 92: 255004.