Fusion reactors inch toward commercialization

[M.D. Holloway]

Fusion reactors inch toward commercialization

R. Colin Johnson
EE Times
12/05/2008 12:32 AM


PORTLAND, Ore. — MIT researchers said they have succeeded in using radio waves to mix the 50 million degree C plasma at its Alcator C-Mod fusion reactor.

While a host of obstacles remain for bringing commercial fusion reactors online, the ability to use radio waves to quell plasma turbulence has been a stumbling block to further progress.

"Ours is the first definitive result showing that high-power radio waves can significantly affect the flow of the plasma," said physicist Earl Marmar, division head of the Alcator Project at MIT's Plasma Science and Fusion Center.


"We launched several million watts of radio waves into the plasma using a dipole antenna at frequencies ranging between 50 and 80 megahertz," Marmar added. "In the process, we are breaking up the turbulent eddies--making them smaller--which will ultimately determine how well the magnetic bottle is confining the plasma."

A doughnut-shaped magnetic bottle is required to confine plasma heated to temperatures that no solid container could withstand. The Alcator C-Mod, which has the highest plasma pressure of any facility, contains plasma using the highest magnetic field of any fusion reactor. Thus, MIT's demonstration of RF "mix and stir" also be used in other fusion reactors, such as International Thermonuclear Experimental Reactor now under construction in France.

Radio frequencies were first proposed to control plasma flow 20 years ago. MIT researchers claim their technique is the first to experimentally confirm that the technique works in a fusion reactor. The RF mix-and-stir method was perfected by MIT physicist Yijun Lin and principal researcher John Rice.

Next, the MIT researchers plan to optimize their process by adjusting the frequency of the radio waves, the strength of the magnetic field and the mix of ions in the plasma.

Nevertheless, several hurdles still must be overcome before fusion reactors can be commercialized, including engineering materials to capture and neutralize the high-energy neutron flux, a by-product of the fusion reaction. Neutrons are not radioactive, but current methods of capturing them in a blanket surrounding the reactor produce radioactive by-products.

Marmar noted that neutron flux is not part of the radioactive waste created when they are captured in a "blanket" surrounding the reactor.

Compared to fusion reactors, current commercial fission reactors produce many times more radioactive waste, with half-lives in the tens of thousands of years. Proponents of nuclear fusion reactors argue that radioactive by-products from the fusing of atoms has a half-life shorter than 100 years.

Fusion critics say confinement and storage of radioactive by-products must still be solved before fusion reactors can be commercialized.

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[onewhippedpuppy]

Nuclear power = the only real answer to our energy crisis. Too bad Washington hasn't realized it.

[Superman]

For now, our best bet is nuclear. But in the future, it will be fusion. It has been predicted that it will take humans until perhaps 2050 to harness the heat of fusion reaction. Fifty million degrees centigrade......they're gonna need a Carrera cooler, with fan.

[onewhippedpuppy]

Originally Posted by Superman

For now, our best bet is nuclear. But in the future, it will be fusion. It has been predicted that it will take humans until perhaps 2050 to harness the heat of fusion reaction. Fifty million degrees centigrade......they're gonna need a Carrera cooler, with fan.

Cool collar baby!

[IROC]

Scaling this RF method to something the size of ITER has not been demonstrated, but it's noteworthy. Too bad the federal government slashed ITER funding in FY08. We are currently running the risk of the rest of the world leaving us (the US) standing at the station as the fusion train pulls out.

Incidentally, my facility is the home of the US ITER project office...

[Pazuzu]

Old news, they've had this working (but SECRETLY) since 1996.

[kach22i]

We already have all the fusion power we can use from our sun. We just need to make more solar panels, tide generators and wind generators to capture some more of it.

[gtc]

Originally Posted by kach22i

We already have all the fusion power we can use from our sun. We just need to make more solar panels, tide generators and wind generators to capture some more of it.

And all we have to do is blanket the four corners in solar arrays!

[equality72521]

Originally Posted by gtc

And all we have to do is blanket the four corners in solar arrays!

Think of all the shade we'll have.

[kach22i]

Originally Posted by gtc

And all we have to do is blanket the four corners in solar arrays!

I think we just need to tap into a few percent of the total energy which reaches us each day from the sun. Something we have been able to do for 30 years.

[red-beard]

Originally Posted by gtc

And all we have to do is blanket the four corners in solar arrays!

Nah. We need Mickey Mouse ears for the planet!

[scottmandue]

I think you guys are underestimating harvesting power from the ocean. Think of all those tides and waves cranking away 24/7.

Although I think we should be developing fusion too.

[Hugh R]

Cool, I worked on one of the first Alcator Tokamak doughnut fusion reactors in 1976/77 at MIT. They had a 210 ton flywheel they got from the NY subway system and they'd spin that sucker up to about 360 RPM, throw in the fieild winding and dump all the juice into dozens of garbage can-sized capacitors. All the copper buss bar was silver soldered at the connections. Just about everything would jump when they pulsed it.

[RWebb]

you can figure that the max. insolation at the Earth's surface is ~~ 1kW/m2
- the real problem is in getting [1] efficiency, and [2] low cost

- think about all the flat-roofed buildings in LA....


Fusion would be nice - if for no other reason you can use it to destroy toxic metals, nuclear waste, etc. - stuff that cann be gotten rid of at all now.

[Esel Mann]

Are we talking about the sort of fusion which always seems to be 20 years away?

[M.D. Holloway]

ya, the big oil companies keep buying up the patents for it and killing off the inventors. Now where did I put that tin foil hat...

[competentone]

Originally Posted by kach22i

We already have all the fusion power we can use from our sun. We just need to make more solar panels, tide generators and wind generators to capture some more of it.

It's much more efficient to just pull the stored fusion power from nature's stores of it in oil, coal and natural gas.

[M.D. Holloway]

Why not just live underground?

[Porsche-O-Phile]

Originally Posted by red-beard

Nah. We need Mickey Mouse ears for the planet!

I'm sure Disney would pony up handsomely to sponsor that!

[RWebb]

Originally Posted by competentone

It's much more efficient to just pull the stored fusion power from nature's stores of it in oil, coal and natural gas.

that releases CO2


oh - I forgot - you have a religious aversion to science...