Mission horizons - experiment at a glance

PK-4 - Ex­plor­ing plas­mas in mi­cro­grav­i­ty - un­der­stand­ing atom­ic pro­cess­es

In the PK-4 facility cold plasmas containing particles are analysed
In the PK-4 fa­cil­i­ty cold plas­mas con­tain­ing par­ti­cles are anal­ysed
Credit: MPE.

In the PK-4 facility cold plasmas containing particles are analysed

In the plas­ma crys­tals ex­per­i­ment PK-4, cold plas­mas con­tain­ing par­ti­cles are anal­ysed. This ex­per­i­ment al­lows for pro­cess­es that ac­tu­al­ly take place at the atom­ic lev­el to be­come vis­i­ble to the hu­man eye. PK-4 serves as a ver­sa­tile tool, en­abling sci­en­tists to il­lu­mi­nate el­e­men­tary phys­i­cal pro­cess­es and with that to fa­cil­i­tate new tech­no­log­i­cal de­vel­op­ments.

Plasma crystal experiments are a flagship European-Russian project as they are among the most successful research efforts having taken place on the International Space Station (ISS). The PKE Nefedov plasma crystal facility was one of the first scientific research laboratories on the ISS. More than 70 scientific publications have documented the findings from the experiments carried out over the last 15 years. Its successor, PK-4, has been operating in the Columbus module since 2014. Thanks to these ISS facilities, researchers are gaining fundamental insights – particularly in solid-state and fluid physics. In addition, applications in space physics, plasma physics and technology as well as technological fluids benefit from this work.

Plasma is an ionised and thus electrically conductive gas that is used in semiconductor and chip technology as well as recently in applications in the field of medicine, to kill multidrug-resistant bacteria in wound treatment and disinfection. If dust particles or other microparticles are also contained in the plasma, they become highly charged, resulting in a ‘complex plasma’. Under microgravity conditions, the particles can spread out freely in space and form ordered, three-dimensional crystal structures. The particles behave in a way similar to atoms in a solid or a liquid, with the advantage that in the plasma each microparticle can be observed individually, as though in slow motion.

Researchers can use this to track at an ‘atomic’ level how a solid melts, a glass forms or flows in liquids change. The results will broaden the understanding of complex plasmas and will play a role in condensed matter physics. Business applications are expected in the fields of semiconductor production (microchips) and electronically controlled liquids, which are used in modern motor drives, valves and shock absorber systems.

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