The PK-4 or (Plasmakristall-4) laboratory is a joint Russian-European laboratory for the investigation of dusty/complex plasmas on board the International Space Station (ISS), with the principal investigators at the Institute of Materials Science at the German Aerospace Center (DLR) and the Russian Institute for High Energy Densities of the Russian Academy of Sciences.
[1] It is the third laboratory on board the ISS to study complex plasmas, after the PKE Nefedov and PK-3 Plus experiments.
In contrast to the previous setups, the geometry was significantly changed and is more suited to study flowing complex plasmas.
Microparticles are then injected into the plasma and move through the tube into the working area where their motion is recorded with two cameras, the images of which are joined for analysis.
The polarity of this electric field can be switched at a high frequency, so that the microparticles can be trapped in the working area.