MIT: LDX fusion advances...

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http://web.mit.edu/newsoffice/2010/fusion-ldx-0125.html

Levitating magnet brings space physics to fusion

Tests on an experimental machine that mimics a planet’s magnetic field show that it may offer an ‘alternative path’ to taming nuclear fusion for power generation.


January 25, 2010

A new experiment that reproduces the magnetic fields of the Earth and other planets has yielded its first significant results. The findings confirm that its unique approach has some potential to be developed as a new way of creating a power-producing plant based on nuclear fusion — the process that generates the sun’s prodigious output of energy.
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The new results come from an experimental device on the MIT campus, inspired by observations from space made by satellites. Called the Levitated Dipole Experiment, or LDX, a joint project of MIT and Columbia University, it uses a half-ton donut-shaped magnet about the size and shape of a large truck tire, made of superconducting wire coiled inside a stainless steel vessel. This magnet is suspended by a powerful electromagnetic field, and is used to control the motion of the 10-million-degree-hot electrically charged gas, or plasma, contained within its 16-foot-diameter outer chamber.

The results, published this week in the journal Nature Physics, confirm the counter-intuitive prediction that inside the device’s magnetic chamber, random turbulence causes the plasma to become more densely concentrated — a crucial step to getting atoms to fuse together — instead of becoming more spread out, as usually happens with turbulence. This “turbulent pinching” of the plasma has been observed in the way plasmas in space interact with the Earth’s and Jupiter’s magnetic fields, but has never before been recreated in the laboratory.
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When operating, the huge LDX magnet is supported by the magnetic field from an electromagnet overhead, which is controlled continuously by a computer based on precision monitoring of its position using eight laser beams and detectors. The position of the half-ton magnet, which carries a current of one million amperes (compared to a typical home’s total capacity of 200 amperes) can be maintained this way to within half a millimeter. A cone-shaped support with springs is positioned under the magnet to catch it safely if anything goes wrong with the control system.

Levitation is crucial because the magnetic field used to confine the plasma would be disturbed by any objects in its way, such as any supports used to hold the magnet in place. In the experimental runs, they recreated the same conditions with and without the support system in place, and confirmed that the confinement of the plasma was dramatically increased in the levitated mode, with the supports removed. With the magnet levitated, the central peak of plasma density developed within a few hundredths of a second, and closely resembled those observed in planetary magnetospheres (such as the magnetic fields surrounding Earth and Jupiter).

Summarizing the difference between the two approaches, Kesner explains that in a tokamak, the hot plasma is confined inside a huge magnet, but in the LDX the magnet is inside the plasma. The whole concept, he says, was inspired by observations of planetary magnetospheres made by interplanetary spacecraft. In turn, he says, for planetary research the experiments in LDX can yield “a lot more subtle detail than you can get by launching satellites, and more cheaply.”
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Shpaget

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Can't wait to see some constructive fusion happening on Earth and a new approach is certainly going to make a sort of a race between different designs.
 
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nimbus

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MSimon isn't that kinda fanboy. Does his assessment not fly?
 
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docm

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Levitation - plasma - controlled catch
[youtube]http://www.youtube.com/watch?v=4BVt2gKHNBA[/youtube]
 
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kelvinzero

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nimbus":37xke6si said:
MSimon isn't that kinda fanboy. Does his assessment not fly?
I really have no idea who MSimon is.

The internet is full of so much bollocks you really have to reject 99.9% of opinions based on pretty superficial grounds so you can concentrate on the rest.

In this case I just saw someone I dont know, on a site called talk-polywell, slagging off thermally based fusion.

It is true that hundreds of millions have probably gone into thermally based fusion and so far it has not payed of, but this does not necessarily mean it is less promising than other methods that have not been investigated. What it absolutely must mean is that a large proportion of scientists, who know way more than you or I, have considered it the most promising approach.

His opinion may be correct but it must be non-representative.
 
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nimbus

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Concentrate on the rest - like someone who might have an air-tight case against thermal fusion.
You're arguing trends instead of this particular case. So we're arguing past each other. I don't know and don't care whether this one approach to fusion (or any other science project) is more or less popular on the internet, only whether it makes sense (and how cool it is, personally). I don't take someone's word for it, that's blind faith.

How are e.g. MSimon's arguments, in that T-P thread, off-base? They're in that thread. It's not a long thread, there's no difficulty to find them.
What it absolutely must mean is that a large proportion of scientists, who know way more than you or I, have considered it the most promising approach.
Are you saying there's no such thing as substantial proportions of scientists that get caught in politicized science, or who would defend one pet project or other because it fills their pocket?
His opinion may be correct but it must be non-representative.
Who cares? Whether it makes sense and is significant is what matters. It would be significant if LDX were as much a dead end for useful fusion as ITER is. As is the assertion in said thread. Same with LDX being as old a dead horse as hinted at in same thread.
 
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Shpaget

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nimbus":19amr71b said:
It would be significant if LDX were as much a dead end for useful fusion as ITER is.
Why would you say ITER is a dead end?
 
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nimbus

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Everything considered together. The ever-delayed commercial phase. It's a money pit. There's no solid refutal that it's not just another jobs program like some other major govt projects (e.g. a lot of NASA), and lots of little clues that favoritism is an established trend WRT to chasing practical fusion (clinging to one particular project instead of dispassionate and impartial ethos). So many other fusion programs all with a timeline roughly on par with ITER, mostly cheaper and/or simpler than ITER.

And like hinted above, some physicists inside ITER not making any bones about it effectively being a science project more than a lean & mean path to commercial phase.
 
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Shpaget

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Well, the entire project is expected to cost €10 billion which is not really that much considering that it spans over 50 years and the number of people living in the participating countries.
It's less than €0.06 per capita per year.

I'd gladly give them my cents.
 
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kelvinzero

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nimbus":qlnvxvlw said:
Concentrate on the rest - like someone who might have an air-tight case against thermal fusion.
You're arguing trends instead of this particular case. So we're arguing past each other. I don't know and don't care whether this one approach to fusion (or any other science project) is more or less popular on the internet, only whether it makes sense (and how cool it is, personally). I don't take someone's word for it, that's blind faith.

How are e.g. MSimon's arguments, in that T-P thread, off-base? They're in that thread. It's not a long thread, there's no difficulty to find them.
What it absolutely must mean is that a large proportion of scientists, who know way more than you or I, have considered it the most promising approach.
Are you saying there's no such thing as substantial proportions of scientists that get caught in politicized science, or who would defend one pet project or other because it fills their pocket?
His opinion may be correct but it must be non-representative.
Who cares? Whether it makes sense and is significant is what matters. It would be significant if LDX were as much a dead end for useful fusion as ITER is. As is the assertion in said thread. Same with LDX being as old a dead horse as hinted at in same thread.
er... Im beginning to wonder if we are looking at the same thread. There were less lines by the guy in that thread than you have just posted. Of course I read it. Here is the total content:
post 1:
Yeah. It was beat to death here about two years back.

A truly stupid idea. They cool the sucker by conduction. Levitate it using a magnetic field. Fuse a couple of atoms and hope to hell they get it back down to the cooling conduction plate before the sucker explodes.

I can see great possibilities. For spending vast sums of money in a never ending quest for thermally driven fusion.

post 2:
Been done. Ask Tom Ligon.

As for whether Scientists can get caught up in politics, well sure.. but you need to assume a bit more than that in order to discount all the money invested in these directions, you would need a full-on conspiracy.

You argue to consider the content rather than the reputation. Ie consider the actual arguments. This sounds very sensible, it sounds modern and rational, but actually it is a fallacy that exposes non-experts to all sorts of hucksters and kooks.

By all means do apply your own common sense! ...But you can really only use this to throw out obvious rubbish.

Beyond spotting blatant flaws, our common sense cannot be expected to pick the right answer. Very obviously this is a difficult problem even for people who have spend decades studying it, or it would have been solved by now.

My argument actually is still scientific rather than simply resting on reputation. I am saying my knowledge of physics (third year university level) is not up to detecting a flaw in what he says, but my knowledge of human behaviour makes the notion of a conspiracy of scientists highly implausible. Occams razor. This is the best we can do without becoming true experts in this field (and even that might not be enough) and no amount of internet browsing or dialog will achieve the required skill.

Im still not saying he is wrong, just that there isnt evidence there that a layman should be convinced by, and merely being on a site called Talk-Polywell does not bode well for finding a non-biased opinion. In fact it was sort of funny.


I have gotten way off topic. I wont continue this here but it could be an interesting subject to continue in some forum along the lines of "How can a layman judge the reliablility of information found on the internet."
 
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nimbus

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kelvinzero":11nkbtus said:
You argue to consider the content rather than the reputation. Ie consider the actual arguments. This sounds very sensible, it sounds modern and rational, but actually it is a fallacy that exposes non-experts to all sorts of hucksters and kooks.
No. So long as I don't get it (e.g. jargon), my opinion's reserved.
Im still not saying he is wrong, just that there isnt evidence there that a layman should be convinced by, and merely being on a site called Talk-Polywell does not bode well for finding a non-biased opinion. In fact it was sort of funny.
Inaccurate. Read t-p more than at a glance and you'll see for yourself.
"How can a layman judge the reliablility of information found on the internet."
Test it.
 
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kelvinzero

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As I said, this is drifting off topic. I will not continue this conversation here because it is really about distinguishing good from bad information, not fusion.

Good luck with your testing. :)
 
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