Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Magnetic fields get reconnected in turbulent plasma too, Cluster reveals

28.03.2007
Using measurements of the four ESA's Cluster satellites, a study published this week in Nature Physics shows pioneering experimental evidence of magnetic reconnection also in turbulent 'plasma' around Earth.

Magnetic reconnection – a phenomenon by which magnetic fields lines get interconnected and reconfigure themselves - is a universal process in space that plays a key role in various astrophysical phenomena such as star formation, solar explosions or the entry of solar material within the Earth's environment. Reconnection has been observed at large-scale boundaries between different plasma environments such as the boundary between Earth and interplanetary space. Plasma is a gas composed of charged particles.

An irregular behaviour of particle flows and magnetic fields causes plasma turbulence within which many small-scale boundaries can form, where reconnection has been predicted via modelling. However, thanks to Cluster this was the first time that this could be directly observed, opening up new perspectives to help us better understand the behaviour of turbulent plasma.

Our first line of defence against the incessant flow of solar particles, the Earth's magnetic field deflects most of this material around the Earth's magnetosphere. This is marked by a boundary layer called the magnetopause. As for any other planet which has a planetary magnetic field (for example Jupiter and Saturn), solar wind is decelerated from supersonic to subsonic speeds by a shock wave (called the 'bow shock') located in front of the magnetopause. The region between the bow shock and the magnetopause is called the magnetosheath.

One of the most turbulent environments in the near-Earth space, the terrestrial magnetosheath is an accessible laboratory to study in-situ turbulence, unlike the solar atmosphere or accretion disks. Characterising the properties of the magnetic turbulence in this region is of prime importance to understand its role in fundamental processes such as energy dissipation and particle acceleration.

Observing reconnection at small-scale boundaries in space requires simultaneous measurements by at least four spacecraft flying in close formation. With an inter-spacecraft distance of only 100 kilometres, on 27 March 2002 the four Cluster satellites observed reconnection within a very thin current 'sheet' embedded in the turbulent plasma with a typical size of about 100 kilometres.

A challenge for the instruments onboard, the observations show that the turbulent plasma is accelerated and heated during the reconnection process. This newly observed type of small-scale reconnection seems also to be associated with the acceleration of particles to energies much higher than their average which could explain, in part, the creation of high energy particles by the Sun.

To quote Alessandro Retinò, lead author of this study and PhD student at the Swedish Institute of Space Physics, Uppsala, Sweden, "we found reconnection in one single current sheet, so that in such an environment of irregular magnetic fields one may think that reconnection is sporadic, but this is not the case. For this particular magnetosheath crossing, a very large number of other thin current sheets was found where reconnection is very likely to occur, a subject currently under investigation by our team."

This discovery of reconnection in turbulent plasma has significant implications for the study of laboratory and astrophysical plasmas, where both turbulence and reconnection develop and thus where turbulent reconnection is very likely to occur. Possible applications range from the dissipation of magnetic energy in fusion devices on Earth to the understanding of the acceleration of high energy particles in solar explosions called solar flares.

"Magnetic reconnection, turbulence and shocks are three fundamental ingredients of the plasma Universe," says Philippe Escoubet Cluster and Double Star project scientist at ESA. "The detailed understanding of these key processes and their associated multi-scale physics is a challenge for the future of space physics. One of the lessons learned from Cluster is the need for new space missions equipped with instruments of higher sensitivity and better time resolution together with a larger number of satellites."

Philippe Escoubet | alfa
Further information:
http://www.esa.int/esaSC/SEMDI3T4LZE_index_0.html

More articles from Physics and Astronomy:

nachricht Physics boosts artificial intelligence methods
19.10.2017 | California Institute of Technology

nachricht NASA team finds noxious ice cloud on saturn's moon titan
19.10.2017 | NASA/Goddard Space Flight Center

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Electrode materials from the microwave oven

19.10.2017 | Materials Sciences

New material for digital memories of the future

19.10.2017 | Materials Sciences

Physics boosts artificial intelligence methods

19.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>