Nonlinear Wave Experiments in Dusty Plasmas

University Of Iowa, Iowa City IA

Investigators

Abstract

This project will utilize a facility called Plasma Krystal-4 (PK-4) on the International Space Station to conduct experiments in microgravity investigating the underlying physics of large amplitude waves. Waves are moving oscillations, which can propagate in many substances. In some substances waves are easily visible, in some they are easily manipulated, and in some the waves attain a large displacement so that they take on a different character called nonlinearity. Attaining all three of these characteristics at the same time is possible in a substance called a dusty plasma, which is a mixture of highly charged micron-size solid particles immersed in a partially ionized gas consisting of electrons, ions, and neutral molecules. In this project, large amplitude waves will be observed using video microscopy and manipulated using an experimental instrument on the International Space Station. An undergraduate student will carry out the analysis. The topic has an overlap with other fields of research including nonlinear dynamics as well as other plasma physics areas outside of dusty plasmas. The data to be analyzed are mainly from the PK-4 instrument, which is a European-Russian apparatus now on the International Space Station. Data returned to Earth are distributed to scientists at other locations including The University of Iowa. A scientific video camera images a cross-section of a cloud of polymer microspheres, which are electrically charged due to their immersion in a weakly ionized plasma. This so-called dust cloud sustains waves such as dust acoustic wave and ionization striations; these waves grow naturally, by an instability, to attain nonlinear amplitudes. The use of data from PK-4 is valuable because under microgravitiy conditions, the dust cloud fills a three-dimensional volume of greater size than is possible in laboratory experiments on Earth. To support this effort the investigators will collaborate with theorists in describing the nonlinear motion. This award to support an undergraduate student is made under a "NASA/NSF Partnership on Science of Dusty Plasmas: Utilizing the PK-4 Facility on board the International Space Station" and is complementary to a NASA award made under the joint program.