Crystal-liquid phase transitions in three-dimensional complex plasma under microgravity conditions

Abstract

Complex (dusty) plasmas are composed of weakly ionized gas and charged micro-particles and represent the plasma state of soft matter. Due to the "heavy" component, microparticles, and the low density of the surrounding medium, the rarefied gas and plasma, it is necessary to perform experiments under microgravity conditions to cover a broad range of experimental parameters which are not available on ground. The investigations have been performed onboard the International Space Station with the help of the PK-3 Plus laboratory. This laboratory was mainly built to investigate the crystalline state of complex plasma, the so-called plasma crystal, its phase transitions and processes in multi-particle mixtures. Due to the manipulation of the interaction potential between the microparticles it is possible to initiate a phase transition from isotropic plasma into electrorheological plasma. The crystal-liquid phase transition was obtained in large three-dimensional isotropic dusty plasma system. First observations of a transition of the dusty plasma system state due to variations of the plasma component density are presented.