The sound in Saturn's rings: Physicists explain nonlinear dust acoustic waves in dusty plasmas

Oct 16, 2012

Dusty plasmas can be found in many places both in space and in the laboratory. Due to their special properties, dust acoustic waves can propagate inside these plasmas like sound waves in air, and can be studied with the naked eye or with standard video cameras. The Ruhr-Universitaet-Bochum physicists Prof. Dr. Dr. h.c. Padma Kant Shukla and Dr. Bengt Eliasson from the Faculty of Physics and Astronomy have published a model with which they describe how large amplitude dust acoustic waves in dusty plasmas behave.

The researchers report their new findings in the journal Physical Review E.

Dusty plasmas are composed of electrons, positive ions, , and dust grains that are negatively or positively charged. Only in plasmas containing electrically charged , dust emerge – the so called dust . These waves are supported by the inertia of the massive charged dust particles. The restoring force – causing the particles to oscillate and the wave to propagate – comes from the pressure of the hot electrons and ions. Recently, several revealed nonlinear dust acoustic waves with extremely large amplitudes in the form of dust acoustic solitary pulses and , propagating in the plasma with speeds of a few centimeters per second. Padma Shukla and Bengt Elisasson have developed a unified theory explaining under which circumstances nonlinear dust acoustic shocks as well as dust acoustic solitary pulses occur in dusty plasmas.

Dust acoustic waves with large amplitudes interact among themselves thereby generating new waves with frequencies and wavelengths different from the ones of the original dust acoustic waves. Due to the generation of harmonics (i.e., waves with frequencies that are a multiple integer of the original frequency) and due to constructive interference between dust acoustic waves of different wavelengths, the waves develop into solitary, spiky pulses, or into shock waves. The solitary pulses arise from a balance between the harmonic generation nonlinearities and the dust acoustic wave dispersion. Shock waves, on the other hand, form when the dust fluid viscosity dominates over dispersion. This happens at high dust densities when the dust particles are close enough to interact and collide with neighboring .

The new Shukla-Eliasson nonlinear theory and numerical simulations of the dynamics of nonlinear dust acoustic waves successfully explain observations from laboratory experiments of three different groups world-wide, in the USA (Robert Merlino), Taiwan (Lin I), and India (Predhiman Kaw). These three international groups described the existence of large dust acoustic solitary pulses and dust acoustic shocks in their low-temperature dusty plasmas. Applying the new nonlinear dust acoustic wave theory, one can infer the dust fluid viscosity from the width of the dust acoustic shock wave. "Our results may also be important as a possible mechanism for understanding the cause of dust grain clustering and dust structuring in planets and in star forming regions," suggests Prof. Padma Kant Shukla.

More than two decades ago, Prof. Padma Kant Shukla theoretically predicted the existence of linear and nonlinear dust acoustic waves in dusty plasmas, which since then have been observed in many laboratory experiments. His discovery has transformed the field of plasma physics, and has opened up a new interdisciplinary research field at the crossroad between condensed matter physics and astrophysics.

Explore further: A new, tunable device for spintronics

More information: P. K. Shukla, B. Eliasson (2012): Nonlinear dynamics of large-amplitude dust acoustic shocks and solitary pulses in dusty plasmas, doi: 10.1103/PhysRevE.86.046402

add to favorites email to friend print save as pdf

Related Stories

Acoustic levitation could be used on Mars

Jan 25, 2010

(PhysOrg.com) -- The presence of fine dust on the Moon and Mars may present problems for explorers, such as coating solar panels, penetrating seals and interfering with machinery. Human explorers would also ...

Quantum microphone captures extremely weak sound

Feb 06, 2012

(PhysOrg.com) -- Scientists from Chalmers have demonstrated a new kind of detector for sound at the level of quietness of quantum mechanics. The result offers prospects of a new class of quantum hybrid circuits ...

What makes the giant freak wave 'stable'

Jun 18, 2010

The dreaded giant freak wave that can appear on the open sea out of nowhere, can now for the first time be theoretically calculated and modelled. Researchers at Umea University and the Ruhr-Universitat Bochum in Germany have ...

Dust Devils Whip By Spirit

Apr 13, 2007

On sol 1120 (February 26, 2007), the navigation camera aboard NASA’s Mars Exploration Rover Spirit captured one of the best dust devils it’s seen in its three-plus year mission. The series of navigation ...

Recommended for you

A new, tunable device for spintronics

13 hours ago

Recently, the research group of Professor Jairo Sinova from the Institute of Physics at Johannes Gutenberg University Mainz in collaboration with researchers from the UK, Prague, and Japan, has for the first time realised ...

Watching the structure of glass under pressure

13 hours ago

Glass has many applications that call for different properties, such as resistance to thermal shock or to chemically harsh environments. Glassmakers commonly use additives such as boron oxide to tweak these ...

Inter-dependent networks stress test

16 hours ago

Energy production systems are good examples of complex systems. Their infrastructure equipment requires ancillary sub-systems structured like a network—including water for cooling, transport to supply fuel, and ICT systems ...

Explainer: How does our sun shine?

17 hours ago

What makes our sun shine has been a mystery for most of human history. Given our sun is a star and stars are suns, explaining the source of the sun's energy would help us understand why stars shine. ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

rubberman
not rated yet Oct 17, 2012
MMM Closer to the truth are we.
Steadfast standard theorists can c'mon down to club Z-pinch for a drink to celebrate the grand re-unveiling of a massive variable in planet formation. Next up, isolating the moment where charge gives way to gravity...followed by a revision to the following article:

http://phys.org/n...lar.html

If they were acoustic waves in dusty plasma, the conclusion by the writer in the article I linked make sense. Otherwise, see the comments section for why it doesn't work as a "stellar shockwave".