Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Taming thermonuclear plasma with a snowflake

08.11.2010
News from the 52nd annual meeting of the APS Division of Plasma Physics

Physicists working on the National Spherical Torus Experiment (NSTX) at the Princeton Plasma Physics Laboratory are now one step closer to solving one of the grand challenges of magnetic fusion research—how to reduce the effect that the hot plasma has on fusion machine walls (or how to tame the plasma-material interface).

Some heat from the hot plasma core of a fusion energy device escapes the plasma and can interact with reactor vessel walls. This not only erodes the walls and other components, but also contaminates the plasma—all challenges for practical fusion. One method to protect machine walls involves divertors, chambers outside the plasma into which the plasma heat exhaust (and impurities) flow. A new divertor concept, called the "snowflake," has been shown to significantly reduce the interaction between hot plasma and the cold walls surrounding it.

Strong magnetic fields shape the hot plasma in the form of a donut in a magnetic fusion plasma reactor called a tokamak. As confined plasma particles move along magnetic field lines inside the tokamak, some particles and heat escape because of instabilities in the plasma. Surrounding the hot plasma is a colder plasma layer, the scrape-off layer, which forms the plasma-material interface. In this layer, escaped particles and heat flow along an "open" magnetic field line to a separate part of the vessel and enter a "divertor chamber." If the

plasma striking the divertor surface is too hot, melting of the plasma-facing components and loss of coolant can occur. Under such undesirable conditions, the plasma-facing component lifetime would also be an issue, as they would tend to wear off too quickly.

While the conventional magnetic X-point divertor concept has existed for three decades, a very recent theoretical idea and supporting calculations by Dr. D.D. Ryutov from Lawrence Livermore National Laboratory have indicated that a novel magnetic divertor—the "snowflake divertor"—would have much improved heat handling characteristics for the plasma-material interface. The name is derived from the appearance of magnetic field lines forming this novel magnetic interface.

This magnetic configuration was recently realized in NSTX and fully confirmed the theoretical predictions. The snowflake divertor configuration was created by using only two or three existing magnetic coils. This achievement is an important result for future tokamak reactors that will operate with few magnetic coils. Because the snowflake divertor configuration flares the scrape-off layer at the divertor surface, the peak heat load is considerably reduced, as was confirmed by the divertor heat flux on NSTX. The plasma in the snowflake divertor, instead of heating the divertor surface on impact, radiated the heat away, cooled down and did not erode the plasma-facing components as much, thus extending their lifetime. Plasma TV images show more divertor radiation in the snowflake divertor plasmas in comparison with the standard plasmas. Importantly, the snowflake divertor did not have an impact on the high performance and confinement of the high-temperature core plasma, and even reduced the impurity contamination level of the main plasma.

These highly encouraging results provide further support for the snowflake divertor as a viable plasma-material interface for future tokamak devices and for fusion development applications.

Saralyn Stewart | EurekAlert!
Further information:
http://www.utexas.edu

Further reports about: Laboratory NSTX Physic Plasma technology hot plasma magnetic coil magnetic field

More articles from Physics and Astronomy:

nachricht From rocks in Colorado, evidence of a 'chaotic solar system'
23.02.2017 | University of Wisconsin-Madison

nachricht Prediction: More gas-giants will be found orbiting Sun-like stars
22.02.2017 | Carnegie Institution for Science

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: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>