Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Magnetic Behavior Discovery Could Advance Nuclear Fusion

21.03.2014

Inspired by the space physics behind solar flares and the aurora, a team of researchers from the University of Michigan and Princeton has uncovered a new kind of magnetic behavior that could help make nuclear fusion reactions easier to start.

Fusion is widely considered the ultimate goal of nuclear energy. While fission leaves behind radioactive waste that must be stored safely, fusion generates helium, a harmless element that is becoming scarce. Just 250 kilograms of fusion fuel can match the energy production of 2.7 million tons of coal.

Unfortunately, it is very difficult to get a fusion reaction going.

"We have to compress the fuel to a temperature and density similar to the core of a star," said Alexander Thomas, assistant professor of nuclear engineering and radiological sciences.

Once those conditions are reached, the hydrogen fuel begins to fuse into helium. This is how young stars burn, compressed by their own gravity.

On Earth, it takes so much power to push the fuel atoms together that researchers end up putting in more energy than they get out. But by understanding a newly discovered magnetic phenomenon, the team suggests that the ignition of nuclear fusion could be made more efficient.

Two methods dominate for confining the fuel, made of hydrogen atoms with extra neutrons, so that fusion can begin. Magnetic confinement fusion uses magnetic fields to trap the fuel in a magnetic 'bottle,' and inertial confinement fusion heats the surface of the fuel pellet until it blows off in a way that causes the remaining pellet to implode. The team explored an aspect of the latter method through computer simulations.

"One of the concerns with nuclear fusion is to squeeze this very spherical fuel pellet perfectly into a very small spherical pellet," said Archis Joglekar, a doctoral student in nuclear engineering and radiological sciences.

To avoid pushing the ball of fuel into an irregular shape that won't ignite, the fuel must be exposed to uniform heat that will cause its surface layer to evaporate all at once. As this layer pushes off at high speed, it applies equal pressure to all sides of the pellet and causes it to shrink to one thousandth of its original volume. When that happens, the fuel begins to fuse.

Joglekar calls even heating "the biggest concern in terms of achieving inertial confinement fusion."

The heat comes from about 200 laser beams hitting the inside of a hollow metal cylinder with the fuel pellet sitting at its heart. The trouble is that the light energy from the laser is converted to heat in the metal by way of electrons, and the electrons can get trapped in magnetic fields created by the laser spots.

When the laser light hits the metal, it turns some of the surface metal into plasma, or a soup of electrons and free atomic nuclei. The laser and the heat drive the electrons to move in a way that sets up a magnetic field circling the laser spot.

The magnetic field acts as a boundary for the electrons—they can't cross it. But until now, researchers didn't know that the hot electrons, in an effort to get to cooler areas, are able to push the magnetic fence outward.

The team showed that the flow of hot electrons could drive the magnetic fields around neighboring laser spots together, causing them to join up. Instead of forming a barrier between the laser spots, the joined fields open a channel between them.

"Now there's a clear path for the electrons to move into what would otherwise be the cold region," Joglekar said.

Designers of inertial fusion ignition systems may be able to use this newly discovered feature to place the laser spots so that they heat the cylinder more quickly and efficiently.

"Essentially, what we found is a completely new magnetic reconnection mechanism," Thomas said. "Though we're studying it in an inertial confinement fusion process, it might be relevant to the surface of the sun and magnetic confinement fusion."

For instance, knowing that the flow of hot, charged particles on the sun can push magnetic fields around could inspire new theories about how solar flares occur.

A paper on this work, titled "Magnetic reconnection in plasma under inertial confinement fusion conditions driven by heat flux effects in Ohm's law," is published in Physical Review Letters. It was carried out in collaboration with Amativa Bhattacharjee and William Fox of the Princeton Plasma Physics Laboratory.

Alexander Thomas: www.engin.umich.edu/ners/people/faculty/alexander-thomas
Abstract: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.112.105004

Kate McAlpine | newswise
Further information:
http://www.umich.edu

Further reports about: Advance Magnetic Nuclear Physical Physics Princeton conditions cylinder electrons fuse gravity heat small

More articles from Physics and Astronomy:

nachricht Tune your radio: galaxies sing while forming stars
21.02.2017 | Max-Planck-Institut für Radioastronomie

nachricht Breakthrough with a chain of gold atoms
17.02.2017 | Universität Konstanz

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

Impacts of mass coral die-off on Indian Ocean reefs revealed

21.02.2017 | Earth Sciences

Novel breast tomosynthesis technique reduces screening recall rate

21.02.2017 | Medical Engineering

Use your Voice – and Smart Homes will “LISTEN”

21.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>