Complex plasma research on the ISS-Results from laboratories PK-3 Plus and PK-4

Kurzfassung

Complex plasmas are plasmas containing small solid particles, typically in the micrometer range, which are charged through the collection of plasma electrons and ions. These plasmas are specially prepared to study fundamental processes in the strong coupling regime on the most fundamental (kinetic) level, through the observation of individual microparticles and their interactions. Complex plasma research under microgravity conditions complements the research in the laboratory. Due to reduction of the main force on microparticles in the lab – gravity - it is possible to form complex plasmas in the bulk region of plasmas in homogeneous large 3D systems and to investigate other phenomena than those accessible on Earth in detail. Therefore, the PK-3 Plus lab was operated as a long-term microgravity facility from 2006 to 2013 on the Russian segment of the International Space Station ISS. Those experiments with three-dimensional complex plasmas showed the variety and interdisciplinarity of the field. Exemplarily the formation and melting of plasma crystals, phase separation in binary mixtures and electrorheological effects will be presented. Although the operation of the PK-3 Plus laboratory stopped in 2013, the promising research of large three-dimensional complex plasmas will be continued with the next microgravity laboratory, PK-4. This was launched in October 2014 and installed into the European Physiological Module in the Columbus Module. It is operational now and available for the next generation of experiments with complex plasmas under microgravity conditions onboard the ISS.