Self-organisation in currents: complex plasmas vs. humans

Complex plasmas ‐ low temperature plasmas with micron sized particles ‐ exhibit various effects of self-organisation. This can be used to simulate the behaviour of matter in nearly any state from solid (crystalline) to liquid ‐ even super-critical states have been realised so far ‐ on the kinetic level of individual particles (‘atoms’). To avoid gravitational effects experiments have been performed under microgravity conditions on parabolic flights and onboard the International Space Station ISS. [1] The ‘Plasmakristall (PK-) 4’ setup uses a HV DC discharge in a glass tube to create a complex plasma for studying mainly fluids on the particle level [2,3]. During parabolic flights we observed another self-organisation effect, so-called ‘lane formation’. This effect occurs under certain conditions [4] when two types of particles pass through each other. It is known from two-component fluids, granular media and even people moving in a crowd [5]. A comparison of these cases with the PK-4 experiment (fig. 1a, b) is given here.