New approach to measurement of the three-dimensional crystallization front propagation velocity in strongly coupled complex plasma

Abstract

The PK-3 Plus laboratory onboard the International Space Station is used to form complex plasma with a liquidlike particle subsystem in a metastable state and to observe the propagation of crystallization fronts corresponding to the surfaces of crystal domains. We propose the ‘axis’ algorithm of solidlike particles identification, which makes it possible to isolate different domains and their surfaces as well. Determination of the three-dimensional front velocity is based on its definition implying that there exists a small area of the domain surface propagating along some line perpendicularly to it. The velocity measured in this way is an important characteristic of the plasma crystallization kinetics. It proves to be almost independent of time and the direction of front propagation and amounts to ca. 60–80 μm s−1.