Energy

New theory could help clear fusion power hurdle

New theory could help clear fu...
Fusion power would allow electricty to be generated using the same processes taking place in the Sun (Photo: NASA)
Fusion power would allow electricty to be generated using the same processes taking place in the Sun (Photo: NASA)
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Fusion power would allow electricty to be generated using the same processes taking place in the Sun (Photo: NASA)
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Fusion power would allow electricty to be generated using the same processes taking place in the Sun (Photo: NASA)
Physicists Luis Delgado-Aparicio and David Gates who have developed a theory that could, if proven, help fusion power become a reality (Photo: Elle Starkman, PPPL Office of Communications)
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Physicists Luis Delgado-Aparicio and David Gates who have developed a theory that could, if proven, help fusion power become a reality (Photo: Elle Starkman, PPPL Office of Communications)

While solar power harnesses energy produced by the Sun, fusion power seeks to harness the very process used by the Sun to generate a practically limitless supply of clean electricity. Despite decades of research and numerous breakthroughs, “net-gain” nuclear fusion is yet to appear. One of the hurdles is the so-called density, or Greenwald, limit that sees the plasmas within experimental fusion reactors (called tokamaks) spiraling apart and disrupting the fusion process. Now scientists have come up with a new theory as to why this occurs that, if proven, could provide a way to clear the density limit hurdle.

In fusion power, energy is generated through the combining of atomic nuclei in plasmas of sufficient heat and density. However, in experiments, minute, bubble-like islands appear in the plasma and collect impurities kicked up from the tokamak wall that cool the plasma. Since tokamak plasma densities are much lower than the Sun’s, tokamak plasma temperatures need to be even hotter than those in the Sun, so any cooling of the plasma can disrupt the process. But surprisingly, simply pumping up the heat doesn’t solve the problem.

Physicists Luis Delgado-Aparicio and David Gates who have developed a theory that could, if proven, help fusion power become a reality (Photo: Elle Starkman, PPPL Office of Communications)
Physicists Luis Delgado-Aparicio and David Gates who have developed a theory that could, if proven, help fusion power become a reality (Photo: Elle Starkman, PPPL Office of Communications)

“The big mystery is why adding more heating power to the plasma doesn’t get you to higher density,” said David A. Gates, a principal research physicist at the U.S. Department of Energy’s (DoE) Princeton Plasma Physics Laboratory (PPPL) and co-author of a proposed solution with Luis Delgado-Aparicio, a post-doctoral fellow at PPPL and a visiting scientist at MIT’s Plasma Science Fusion Center. “This is critical because density is the key parameter in reaching fusion and people have been puzzling about this for 30 or 40 years.”

The scientists believe that the islands’ detrimental effect on the fusion process is actually twofold. While the impurities cool the plasma, they believe that they also act as shields that block out added power. When the islands grow large enough, more power escapes from the islands than can be pumped into the plasma using ohmic - or joule - heating, causing the electric current that helps to heat and confine the plasma to collapse. This allows the plasma to fly apart in a flash of light.

Using a tokamak called Alcator C-Mod located at MIT, and the DIII-D tokamak at General Atomics in San Diego, Gates and Delgado-Aparicio hope to put their theory to the test in a number of experiments. One of these will involve injecting power directly into the islands to see if that leads to higher density. If it does, it could allow future tokamaks to attain the extreme density and temperatures that fusion requires.

Source: PPPL

18 comments
Todd Dunning
This illustrates the damage that Eco-Greenies have done to the environment as well as science. Ignoring (or just ignorant of) the science of the sun - nuclear energy - they've lined their pockets with billions wasted on wind and other greenwashed boondoggles. Money diverted from real science (nuclear power) and into the feelgood pseudoscience that brought us 'global warming'. When fusion kicks in a few years from now, billions more will have to be spent to remove windmills and their ilk from the land and seabeds. The pedal-powered cars will be tucked into the closet. With power as unlimited and plentiful as the sun, Green Luddites will have to endure prosperity across the world instead of their self-hating prison of trickle-up poverty.
Paul Smith
No, this illustrates your complete lack of knowledge. IF this theory pans out, and IF in the next twenty years they manage to build one and IF they find a way to contain it and IF they have a solution for the waste, and IF the sites can be secured from terrorist threat, and IF they can be built cheaply enough, then we can relax and enjoy the benefits. Until then the Eco-Greenie scientists can continue to offer clean renewable power that is scalable and is beginning to compete financially with the fossil fuels and to employ tens of thousands of people. :>)
Derek Howe
Your both right (Todd & Paul), hopefully nuclear fusion is the future, but it is at least a decade away...more likely 2 decades. We need to have power until that time, so we need to continue investing in other forms of energy capturing/creating methods.
Slowburn
Fusion is a will-o'-the-wisp that helps keep us from using technology that works.
Geometeer
Can we quit repeating the nonsense that "fusion power seeks to harness the very process used by the Sun"? The proton-proton fusion event is very low probability, so that even at the density of the solar core, it produces about as much heat per second per cubic inch as the metabolism of a resting human. The sun is very very big, so that's a lot of heat: but run that process in a power station, and you would not "generate a practically limitless supply" of electricity, clean or otherwise. Earthbound fusion power efforts don't start with protons (hydrogen nuclei). They use deuterium (proton with an added neutron) or tritium (with two), using much higher tempertaures and muchlower densities. They may succeed something good, or they may not, but the sun is not a proof of possibility.
johnqp
I wonder why people think this will be any safer or less polluting than Fission? Yes, the energy gains would be great but what about waste etc. Our Sun gives off some pretty nasty energies - using the same process even at a reduced scale would give off the same energies wouldn't it? Just spit balling here.
Phillip Noe
Does Todd Dunning prefer trickle down prosperity for the few at the expense of the many? Or does he think that the general "greenie" efforts are just self-serving and not for the benefit of the earth's long-term habitability? Can we afford nuclear now or maybe just wait for the fusion fantasy to arrive? Looks like his focus is nuclear without regard to many other more realistic and immediate solutions. Is he just another closed minded republicon? Probably.
Adrian Akau
Practical fusion is probably decades away. Meanwhile, we should look into LENR heat producing reactions such as the one used by Rossi's E-Cat. He is supposed to have a 1 Mw plant completed in the US this year that will be open to public inspection. LENR type reactions in the E-Cat produce low temperature steam (higher temperatures cause instability) but Siemens has taken an interest and is designing a turbine that could be used. If practical LENR devices could be made safe for home use in 5-10 years, then I would like to purchase one.
StWils
Solar PV, Wind, and increasingly, the emerging wave or ocean generated power is already very cost effective at almost any scale. Once the hardware is built these systems have long lives and typically few environmental downsides. Earlier attempts sometimes have some issues but the industry has evolved very fast over the last ten years and will continue to improve. The sun gives us more energy in an hour than we consume in ALL forms in a year so it is entirely possible to derive ALL of our energy needs and also a lot of material needs from manipulating solar energy. Batteries are getting better, slowly, but it is happening, there are other energy storage methods, hydrogen, water impoundment, compressed air, bio-mass, etc, all of which will have a useful niche. Collectively these opportunities can reshape industry, our economies, and societies. Unlike Slowburn's clear desire to have everyone using the same coffee can for dinnerware, a personal shower and can-to-take-a-dump-in, mankind can live well and nondestructively at the same time.
MasterG
I really would like to have a mr.Fusion of my own but they are right the nasty byproducts are quite nasty. We dont even need fusion we already got it (the sun) we havent even been able to properly crack the efficiency/power problem from our only example what makes you think we are capable of earth based fusion that wont kill us all? Read a scifi story when i was a kid about how the first successful attempt at fusion turned earth into a selfconsuming black hole because we didnt know how to handle or use all that power.