Complex/Dusty Plasma Physics – from Laboratory to Space

Abstract

A dusty plasma is a plasma containing small solid particles in the range from nanometers to millimeters. Historically, dust in plasma was first observed by Langmuir in his pioneering work on plasma discharges in the 20ies of the last century. Nevertheless, dusty plasma research was concentrated on theoretical aspects of dust in space plasmas, like in cometary tails, Saturn rings, interstellar matter or star and planet forming clouds for a long time. Only in the late 1980ies laboratory research started since the plasma processing industry found the growth of dust particles in their production devices – a growth which diminished the efficiency of their processes. However, the biggest step in the dusty plasma research happened 25 years ago when in 1994 the Coulomb crystallisation of particles, charged in the plasma – the so-called plasma crystal – was discovered. Starting with this, the research broadened from plasma physical aspects to classical condensed matter physics relying on the special properties of investigation of phenomena like melting or crystallisation, defect motion, or wave propagation in solids and liquids on the most fundamental - the individual particle level. Soon, it was recognized that strongly coupled dusty plasma is a new form of soft matter with many similarities to complex fluids. This was the reason to create the new field of “complex plasmas” to distinguish natural or by chance occurring dusty plasmas from plasmas were dust particles – in most cases monodisperse and spherical microparticles – were introduced on purpose. Due to the large mass of the microparticles gravity becomes the dominating force in the laboratory. To overcome this complementary research under microgravity conditions has been performed right from the beginning of the research, starting with parabolic flights and a sounding rocket in 1996, experiments on the Russian MIR Space Station in 1998 and followed by the long-term program on the International Space Station ISS from 2001 until now. The presentation will overview and highlight the research on complex plasmas from the laboratory to space over the last 25 years.