Dust in plasmas - fiend or friend

A survey of research in the field of low-pressure dusty plasmas is given. Formation of macroscopic dust particles from nanometer to micrometer size in low-pressure gas discharges has been recognized as a complex and rich in consequences phenomenon. Here various particle-related aspects are treated. The presented fundamental issues are the behaviour of a dust particle in the plasma, its charging and the gas-dynamical and electric forces acting on a particle. The interactions between the plasma and the particles are discussed and typical examples are given. Also the origin of particles in the plasma is discussed, and the formation mechanisms are classified. Furthermore the main experimental methods in the investigation of dusty plasmas are described and illustrated. Finally, the industrial relevance is sketched. From the historical point of view, dust particles are dangerous contaminants in surface processing plasmas. The research effort in the area of dusty plasmas initially aimed at avoiding particle formation and controlling the contamination level in industrial reactors. Nowadays dusty plasmas have grown into a vast field, where the most fascinating research lines are concentrated on the active use of particles. Many situations in which one can profit from the presence of particles have been found. In the near future, the investigators will be challenged both to satisfy the increasing needs for plasma-produced particles and to uncover new applications.