Putting the brakes on runaway electrons brings fusion power a step closer
A functional fusion reactor may still be a dream, but it's a dream that is slowly becoming a reality with numerous research efforts and experiments aiming to unlock the nearunlimited supply of clean energy that such a reactor would provide. The challenges scientists face in gettingnuclear fusion to work are undeniably difficult, but not insurmountable, and twoyoung physicists have recently solved one of the major problemsengineers have been grappling with for almost half a century.
Nuclear fusion is the process thatpowers our sun. Deep inside our home star, hydrogen atoms aresquashed together to form helium. This fusion process releases huge amountsof energy, but requires extremely high pressures and temperatures and has been challenging to recreate in acontrolled way here on Earth.
Last year, researchers at MIT brought us closer to a fusion future by placing plasma under what they say is the most pressure ever created in a fusion device. Now,two researchers from the Chalmers University of Technologyhave unlocked another piece of the puzzle.
One of the problems engineers havefaced as they develop modern experimental tokamak type fusion reactors is that ofrunaway electrons. These are electrons with extremely high energy that can suddenly, and unexpectedly, accelerate to incredibly highspeeds that can destroy the reactor wall without warning.
|Mia Halleröd Palmgren/Chalmers CC-BY 3.0|
Doctoral students Linnea Hesslow andOla Embréus have devised a new technique to effectively deceleratethese runaway electrons by injecting "heavy ions", such as neon orargon, into the reactor. As the electrons collide with the highcharge in the nuclei of these ions, they slow down and become much morecontrollable.
"When we can effectively deceleraterunaway electrons, we are one step closer to a functional fusionreactor," says Linnea Hesslow.
Hesslow and Embréus have created a model that can effectively predict the electrons' energy and behavior. Using mathmatical descriptions and plasma simulations the physicists are now able to effectively control the speed of the runaway electrons without interrupting the fusion process.
The nuclear fusion challenge is not asimple or easy task to overcome, but each little development such asthis one brings us closer to the clean energy through fusion dream. The Chalmers team isincredibly optimistic that a fusion-powered future is possible.
"Many believe it will work, but it'seasier to travel to Mars than it is to achieve fusion," says Linnea Hesslow. "You could saythat we are trying to harvest stars here on earth, and that can taketime. It takes incredibly high temperatures, hotter than the centerof the sun, for us to successfully achieve fusion here on earth.That's why I hope research is given the resources needed to solve theenergy issue in time."
The discovery was recently published in the journal Physical Review Letters.