New method to ease n-fusion for energy production
Widely considered as the ultimate goal of nuclear energy, just 250 kg of fusion fuel can match the energy production of 2.7 million tonnes of coal. But getting a fusion reaction going is so difficult that researchers often end up putting in more energy than they get out.
This is likely to change soon as a team of researchers has discovered a new kind of magnetic behaviour that could help make nuclear fusion reactions easier to start.
The team of researchers from University of Michigan and Princeton University in the US took inspiration from space physics behind solar flares and the aurora.
"Essentially, what we found is a completely new magnetic reconnection mechanism," said Alexander Thomas, an assistant professor of nuclear engineering and radiological sciences at University of Michigan.
It takes a lot of power to push the fuel atoms together and start the fusion, but by understanding the newly discovered magnetic phenomenon, ignition of nuclear fusion could be made more efficient, the team suggested.
For the fusion to begin, researchers generally apply two methods for confining the fuel, made of hydrogen atoms with extra neutrons.
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.
"Heating is the biggest concern in terms of achieving inertial confinement fusion," added Archis Joglekar, a doctoral student in nuclear engineering and radiological sciences.
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 study added.
The magnetic field acts as a boundary for the electrons - they can not cross it.
Until now, researchers did not 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 neighbouring 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 is a clear path for the electrons to move into what would otherwise be the cold region," Joglekar noted.
(Posted on 20-03-2014)