Latest Results on Complex Plasmas with the PK-3 Plus Laboratory on Board the International Space Station

Abstract

Complex plasmas are low temperature plasmas 1 that contain microparticles in addition to ions, electrons, and 2 neutral particles. The microparticles acquire high charges, 3 interact with each other and can be considered as model par-4 ticles for effects in classical condensed matter systems, such 5 as crystallization and fluid dynamics. In contrast to atoms in 6 ordinary systems, their movement can be traced on the most 7 basic level, that of individual particles. In order to avoid dis-8 turbances caused by gravity, experiments on complex plas-9 mas are often performed under microgravity conditions. The 10 PK-3 Plus Laboratory was operated on board the Interna-11 tional Space Station from 2006 -2013. Its heart consisted of 12 a capacitively coupled radio-frequency plasma chamber. Mi-13 croparticles were inserted into the low-temperature plasma, 14 forming large, homogeneous complex plasma clouds. Here, 15 we review the results obtained with recent analyses of PK-3 16 Plus data: We study the formation of crystallization fronts, 17 as well as the microparticle motion in, and structure of crys-18 talline complex plasmas. We investigate fluid effects such as 19 wave transmission across an interface, and the development 20 of the energy spectra during the onset of turbulent micropar-ticle movement. We explore how abnormal particles move 22 through, and how macroscopic spheres interact with the mi-23 croparticle cloud. These examples demonstrate the versatil-24 ity of the PK-3 Plus Laboratory. 25 28 53 Weightless complex plasmas show a wealth of interest-1 ing phenomena such as relatively stress-free crystallization 2 [9,14], waves [15, 16], lane formation [17, 18], electrorhe-3 ology and string formation [19-22], cavitation and Mach 4 cones [23-25], etc. Laboratories to study complex plasmas 5 were already used on board the Mir space station [26], and 6 were among the first scientific experiments on board the In-7 ternational Space Station (ISS) [9]. The Russian-German 8 PK-3 Plus Laboratory was operated on the ISS from 2006 9 -2013 [27-29], and the state-of-the-art Russian-European 10 PK-4 Laboratory is currently on board [30, 31]. Data analy-11 sis from PK-3 Plus is still on-going, and here we will review 12 some of the latest results. 13 Fig. 1 shows a sketch of the heart of the PK-3 Plus Lab-14 oratory, the plasma chamber. A plasma was produced in a 15 vacuum chamber filled with argon or neon gas at pressures 16 between 5 and 255 Pa by applying a radio-frequency elec-17 tric field to two parallel electrodes with a distance of 3 cm 18 and a radius of 6 cm. The electrodes were surrounded by 19 1.5 cm wide grounded guard rings in which particle dis-20 pensers were embedded. The dispensers were shaken elec-21 tromagnetically in order to inject monodisperse silica and 22 78

Penetration of a supersonic particle at the interface in a binary complex plasma

“…The simulations were performed with 4000 small particles and 1500 big particles, using LAMMPS in NVE ensemble [46]. The rest of the parameters were set as in Table I [20,41,47]. Note that the simulation was performed in the Cartesian coordinate system, while the analysis was performed in cylindrical coordinates, considering the symmetry of the system.…”

Spontaneous dust pulse formation in the afterglow of complex plasmas under microgravity conditions

“…The experiments presented here were performed in the PK-3 Plus Laboratory [20,[43][44][45] which was a Russian-German laboratory hosted on board the ISS during 2006 -2013. This microgravity laboratory made it possible to explore the interdisciplinary features of complex plasmas with several dedicated experiments on diverse topics such as the heartbeat instability and its effect on the microparticle dynamics [46,47], phase separation [48], lane formation [49], crystallization [48,[50][51][52], electrorheological plasmas [53], and interface effects [54,55].…”

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

“…We have mixed these two channels to a 50 Hz progressive scan video. The cameras and lasers are mounted on a horizontal translation stage allowing a depth scan through and, therefore, a 3D view of the complex plasma [15,22,23].…”