Aboard the ISS, researchers investigate complex dust behavior in plasmas

August 7, 2018, American Institute of Physics
This image shows a self-excited dust density wave. Credit: Jaiswal et al.

400 kilometers above Earth, researchers examined waves in complex plasma under microgravity conditions and found that the microparticles behaved in nonuniform ways in the presence of varying electrical fields. They report some of the first findings from the Plasma-Kristall 4 (PK-4) experiment in Physics of Plasmas.

PK-4 is a collaboration between the European Space Agency and the Russian State Space Corporation "Roscosmos" to investigate complex plasmas. Complex or dusty plasmas contain electrons, ions and neutral gas, as well as microparticles such as dust grains. The microparticles become highly charged in the and interact strongly with each other, which can lead to liquid or even crystalline behavior within the complex plasma. The most important property of such a system is that investigations of physical phenomena can be performed on the individual (micro-) particle level allowing new insights into fluid and solid-state physics.

Gravity distorts most complex plasmas experiments on Earth, so the microgravity environment on the International Space Station enables otherwise impossible research. In February 2017, researchers from the DLR-Institute of Materials Physics in Space at the German Aerospace Center (DLR) and Joint Institute for High Temperatures of the Russian Academy of Sciences observed dust density waves or visible sound waves as they moved through the complex plasma.

In the experiment, a microparticle cloud drifted in a plasma with a constant direct current and formed self-excited wave patterns. After that, the discharge polarity was reversed. Although the field strength was nearly identical for both discharge polarities, the exhibited bifurcations: A new wave crest formed between the two old crests in the head of the microparticle cloud.

"The most interesting finding was the velocity of these waves strongly depends on the electric field, which is exciting the waves," said Mikhail Pustylnik, an author on the paper. "We expect to encounter these types of waves in astrophysical situations where you might have dust—in a cometary tail, for example."

"Many plasma processes are also used in the ," Pustylnik said. Dust poses big challenges for the semiconductor industry because particles may damage a silicon wafer during manufacturing. Starting this fall, the researchers are planning additional experiments that will vary the range of electric fields by switching the polarity of the discharge.

Explore further: ESA image: The ESA-Roscosmos Plasma Kristall-4 (PK-4) experiment

More information: "Dust density waves in a dc flowing complex plasma with discharge polarity reversal," Physics of Plasmas (2018). DOI: 10.1063/1.5040417

Related Stories

Fusion scientists find inspiration in atmospheric whistles

May 3, 2018

The challenge of fusion energy is often equated to capturing—and holding—lightning in a bottle. The analogy is apt. Lightning and a fusion energy plasma have a lot in common. Similarities include very high temperatures, ...

Recommended for you

How heavy elements come about in the universe

March 19, 2019

Heavy elements are produced during stellar explosion or on the surfaces of neutron stars through the capture of hydrogen nuclei (protons). This occurs at extremely high temperatures, but at relatively low energies. An international ...

Trembling aspen leaves could save future Mars rovers

March 18, 2019

Researchers at the University of Warwick have been inspired by the unique movement of trembling aspen leaves, to devise an energy harvesting mechanism that could power weather sensors in hostile environments and could even ...

Quantum sensing method measures minuscule magnetic fields

March 15, 2019

A new way of measuring atomic-scale magnetic fields with great precision, not only up and down but sideways as well, has been developed by researchers at MIT. The new tool could be useful in applications as diverse as mapping ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.