Nuclear Fusion Edge Instability Problem Tackled

A possible way to prevent super-hot gases in fusion reactors from damaging the containment vessel has been discovered, which could make fusion a more viable energy solution.  Fusion reactors generate power by heating hydrogen plasma to 100 million degrees Celsius. This causes hydrogen isotopes to fuse together and release energy. But the blistering plasma has to be contained within a vessel using a donut-shaped magnetic field, created using several powerful superconducting magnets. Over time, the reactor's plasma-containing vessel will inevitably be damaged by instabilities known as "edge-localized modes" (ELMs)¹ that occur when hot plasma bursts out of the magnetic field.

Unless these ELMs can be controlled, expensive components need to be replaced regularly. Researchers at General Atomics discovered that by using a separate magnetic coil to induce small perturbations in the reactor's main magnetic field, they found that they could bleed off enough of the plasma particles to prevent the ELMs from bursting out.

The potential solution, tested at  an experimental reactor run by General Atomics, could make the next generation of fusion reactors more efficient, saving hundreds of millions of dollars a year. The method could be incorporated into the latest prototype fusion test reactor – the International Tokamak Experimental Reactor (ITER).  Uncontrolled ELMs could be expected to damage a part of the ITER reactor called the diverter, which collects and removes helium (a by-product of the fusion reaction). This could have to be replaced every six months to a year says Todd Evans, a plasma physicist with General Atomics. "

Any changes to the ITER must go before an advisory group, notes Bill Spears, a spokesman for the project in Garching, Germany. He adds that there is no consensus on the amount of damage ELMs will cause. Currently, the plan is to only replace the reactor's diverter every two-to-three years, he says.

1.  ELMs are MHD (Magnetohydrodynamic) instabilities driven by the steep temperature and density gradients, occurring at the edge of H-Mode plasmas. They are basically short bursts of particles and energy at the edge.

Resources:

Nuclear fusion plasma problem tackled, NewScientistTech, May 22, 2006
ESOL simulation illustration from European Fusion Development Agreement-JET Bulletin, March 2006

Comments

[amazingdrx]

This is marginally encouraging Jim, but I think the superconducting technology used in this project ought to be the focus for the present.

That could store the vast amounts of electricity needed to smooth the supply/demand mismatch from renewable sources.

Then when room temp superconductors, superconducting solar PV cells, and transmission lines come into production someday we may never again need to mess with the danger of nuclear power. Even fusion produces dangerous waste and has the potential for leaks.

Tritium in groundwater is now becoming a devestating problem from present reactors. There is no practical way to ever filter it out of groundwater.

[atrazine]

amazingdrx: Doesn't tritium have a half life of only a few years? As long as we can prevent new tritium from leaking into the water, the problem will resolve itself.

[amazingdrx]

That would be comforting atrazine (!?!), I hope you are right.

A lot of extra cancer cases are being atributed to it in Florida and Mass. I dount the government/industry nuclear cabal will even plug the leaks, it went on for decades and was covered up.

Are they inspecting other plants that have yet to be doscovered leaking, there too, very doubtful.

With these guys it's out of sight out of mind, (im)plausible deniability and coverup is the rule. Honesty, safety, and efficiency is almost nonexistent.

Operating behind a patina of faux security and top secrecy will tend to do that to any sector.

[Engineer-Poet]

If you think he's not right, you obviously think the laws of physics (nuclear decay) are subject to equivocation or debate.

That would make you mighty stupid.

[amazingdrx]

"Tritium has a half-life of 12.3 years and emits a very weak beta particle."

http://www.epa.gov/radiation/radionuclides/tritium.htm

"That would make you mighty stupid."

Or it might make me too stupid to use google before calling others stupid. Or even stupid enough to claim to be a poet, with no evidence of any poetry?

Amazing isn't it. Hehehey.

[Engineer-Poet]

You may not realize that:

1. 12.3 years is just a short time (if you are not much older, I guess you wouldn't).
2. That's more than 8 half-lives per century.
3. The half-life of tritium in the body is roughly 3-10 days.

For all intents and purposes, the only places tritium will conceivably be a problem is in the immediate vicinity of its release point, we can easily treat exposed people by giving them water from elsewhere to drink, and the problem will disappear by itself over barely more than a human lifetime.  You will find few toxic hazards which are so benign, easily treated and self-healing.

[amazingdrx]

Yeah riiight. No problem. Chug a big glass full.

Make it rhyme.

And of course ciggs don't cause cancer either.

[Whitehall]

This sounds like a bit of puffery to me.

Is not the critical issue energy loss from the plasma to the container? Internal parts life improvements are fine and dandy but if the process doesn't return substantial net energy, part life doesn't matter.

I could be wrong - if so please educate me.

As to tritium, I calculated that the releases of tritium in Illinois is a dozen wristwatches at year or so. BFD.

[amazingdrx]

Tritium pollution:

http://amazngdrx.blogharbor.com/blog/_archives/2006/3/17/1825975.html

It's real!

[sara]

I have two questions. Does anyone know who are the top academics in nuclear fusion today? also does anyone know who is the leader in nuclear fusion apparatus development? thanks

[M. Simon]

Sara,

Bussard Fusion Reactor
Easy Low Cost No Radiation Fusion
IEC Fusion Newsgroup
IEC Fusion Technology blog

[S.Ikegami]

google clik "MHz θ　pinch"
Long plasma confinement should be given up.
MHz inertia confinement can be possible by MHz strong magnetic field coil.

[S.Ikegami]

google clik "MHz θ　pinch"
Long plasma confinement should be given up.
MHz inertia confinement can be possible by MHz strong magnetic field coil.

[S.Ikegami]

google clik "MHz θ　pinch"
Long plasma confinement should be given up.
MHz inertia confinement can be possible by new MHz strong magnetic field coil.