New 'Stellarator' Design for Fusion Reactors 171
eldavojohn writes "The holy grail of fusion reactors has always seemed 'just a few years off' for many decades. But a recent design enhancement termed a 'Stellarator' may change all that. The point at which a fusion reactor crashes is when particles begin escaping due to disruptions in the plasma. A NYU team has discovered that coiling specific wires to form a magnetic field may contain the plasma. This may be a a viable way to create a plasma body with axial symmetry, and a far better chance of remaining stable. Like other forms of containment this does require energy itself, but could bring us closer to a stable fusion reactor. It may not be cold fusion or 'table top' fusion but it certainly is a step forward. The paper is up for peer review in the Proceedings of the National Academy of Sciences."
Princeton 1951 called... (Score:2, Insightful)
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--Anyhow -- Star Trek knew about the whole "magnetic bottle" thing back in the 60's. They were talking about "dilithium crystals", but the concept evidently carries over IRL.
If they used... (Score:4, Funny)
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Re:If they used... (Score:4, Funny)
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Re:If they used... (Score:5, Insightful)
Researchers are not involved in corner cases that might never happen. Nor are they worried about reliability yet (in the sense of preventing another Chernobyl, as opposed to the sense of very little downtime). They are just trying to get the blamed thing to produce enough energy to sustain itself, with some left over. (Although, if you're feeling pessimistic enough, you might call that a corner case that might never happen!)
I agree that we need to get a lot of funding to fusion research, but throwing money at the problem won't necessarily solve it. It is a very hard problem. Furthermore, we'd need not just one crazy (I presume you refer to the office of the President), but a whole bunch of crazies (half of Congress), because Congress makes the budget.
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That might be so, but it certainly isn't economical, otherwise we would already have all our energy from renewable sources. Furthermore, very few renewable sources of energy shows any sign of promise in the short term, although solar certainly seems interesting once someone comes up with a "breakthrough". Oh, and we could build more dams, they can certainly be profitable, but often takes a huge toll on mother nature.
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Stellarators aren't new (Score:4, Informative)
Re:Stellarators aren't new (Score:5, Informative)
Somebody over at physorg got a little too excited about a fairly low-impact paper from NYU. If you read the abstract, you'll see that the paper just deals with the design of the coils for a stellarator.
Most likely, this is for the National Compact Stellarator Experiment (NCSX) being built at nearby Princeton, which will be the first stellarator designed with a computer optimized plasma geometry. I think it will also be the largest stellarator to date, with 12 MW of heating capacity. In contrast, the JET Tokamak has 37 MW and the ITER Tokamak will have 110 MW of heating. Unlike ITER, NCSX will not be capable of break-even operation.
Stellarators often get mentioned in fusion power discussions because they provide a more stable containment design, whereas a Tokamak needs one extra set of electromagnets to deal with the fact that the magnetic field is weaker at the outside of a torus of magnets than at the inside. Although a stellarator is therefore a little simpler in that regard, the geometry and plasma modelling is much more complex, and this in turn creates problems for designing the coils and the exhaust diverter. Because of this, most of the funding and research effort has gone to the Tokamaks.
A little more info here: http://en.wikipedia.org/wiki/Stellarator [wikipedia.org]
Anybody care to bet on whether this shows up on CNN's tech page in a day or two as some major "recent design enhancement?"
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I haven't read enough to really grasp why that's better, but 12MW is going t
input-output (Score:3)
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Picture Chinese handcuffs
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It could also be that it's a brute force attempt to force cohesion, and since force must be met with equal force it's very difficult. That also assumes it could concentrate the exact amount of energy at exactly the right point. Just imagine trying to not only stop a terrorist attack, but subdue them without lethal force. They need one leak to win. You need a perfect record.
Re:input-output (Score:5, Informative)
Energy is the ability to do work. Power is the rate at which work is done or energy is extracted.
The plasma contains a great amount of thermal energy with a tendency to do work (by difussing to the reactor walls), so you have to set up a barrier to accomplishing that work. This is analogous to a dam holding back water. The water, due to it's elevation, has a lot of potential energy, but no power is required to hold it back. Power is extracted as it's let through the turbines.
It's a little more complicated for a plasma. A charged particle moving through a varying magnetic field (like that surrounding the reactor) does work and thereby loses energy. As a result, there is a tendency, although less definite than with a dam and water, for the hydrogen ions to only move around in the reactor along lines of constant magnetic field strength.
Once a magnetic field is established, it ideally takes no energy to maintain, except as charged particles move through it. So power only has to be supplied to the electromagnets to account for their inefficiency (0 under ideal conditions in a superconducting Tokamak) or as work is done on the field by charged particles escaping. Since most of the energy from the reactions is carried away by neutrons, which have no electric charge and therefore don't affect the field, the containment power is sufficiently smaller than the reaction power that this is theoretically feasible as a power plant.
Actually, the biggest power demand in a Tokamak as I understand is for heating the plasma to a temperature where fusion will take place. The hotter it gets, the faster fusion occurs, eventually reaching a breakeven point energy is released by fusion faster than it is carried away by escaping neutrons and gamma rays. Then the plasma can sustain itself. We haven't gotten there yet.
Sorry, the dam analogy isn't great and talking about charged particles in a magnetic field is a little abstract. Hope this helps.
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Actually, the biggest power demand in a Tokamak as I understand is for heating the plasma to a temperature where fusion will take place. The hotter it gets, the faster fusion occurs, eventually reaching a breakeven point energy is released by fusion faster than it is carried away by escaping neutrons and gamma rays. Then the plasma can sustain itself. We haven't gotten there yet.
Some subtleties:
Fusion reaction rates are proportional to temperature, but only up to a certain point. The trend is roughly parabolic.
'Breakeven' is usually calculated on the assumption that energy leaving the plasma is reinjected with a certain efficiency, typically 1/3. 'Ignition' is when the fusion reaction can go on without any external power input.
Also, I realize it's a rough analogy, but the dam picture is inadequate. My professor described fusion confinement as "trying to hold jell-o with string".
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For the most part it is true that static fields are employed. Indeed, this is the goal of the stellarator, where we get the field configuration perfect through exquisite design and manufacturing! In tokamaks, anyway, control of plasma shape, position, and stabilization of vertical instability are all done with slight perturbations to the applied magnetic field. On all modern tokamaks, they do in fact vary -- just very slightly.
You also have attempts to impose magnetic field variations due to the existence
Re:input-output (Score:5, Informative)
The energy that a plasma intrinsically has (like kinetic energy) is just that; energy.
Here's a related (but certainly not airtight) analogy: A brick can have some gravitational potential energy relative to the earth's surface. If you're standing on the ground, that brick will have some nominal gravitational potential energy. If you lift that brick 1 meter, you'll do some amount of work. If you're hanging over the edge of a helicopter at a couple hundred meters, that brick has substantially higher gravitational potential energy. However, if you lift the brick a distance of 1 meter, you'll still do the same amount of work.
So, what's going on here is that a plasma can indeed have a lot of energy (relative to the earth's environment). However, the "energy" we're putting in is actually work to contain that plasma.
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There are two aspects to answer your question properly:
Huh... (Score:3, Funny)
* Sure it doesn't say they figured it out in TFA but humanity will point to this day and say 'That is the day SCO lost and they figured out fusion.'
Thorium reactors (Score:5, Interesting)
Does anyone know any more about this?
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If you want to see thorium-fuelled fission reactors in operation, you'll probably want to go to India. They're sitting on about a quarter of the world's thorium supply, and quite reasonably think that they ought to get some use out of the stuff.
Re:Thorium reactors (Score:4, Interesting)
It's important to define 'better' here. Cost would seem to be an important consideration, for example. I don't know what the price tag of fusion is so far, but it's awfully, awfully high already and without a great deal to show for it. If we've already got a pretty good thing in thorium, and we already have the reactors, and there's enough thorium and uranium to keep us in electricity at present consumption rates for thousands of years, and it's non-polluting and all the rest, then how is fusion - a hugely expensive, so far unproductive technology - 'even better'. I'm not quibbling or trying to be antagonistic here - it's a serious question, and it needs a serious answer considering what's at stake: we need clean, non-polluting power that doesn't ultimately come from politically volatile parts of the world.
Re:Thorium reactors (Score:4, Informative)
Uranium reserves are estimated to be about 85 years at present use. Plans to extend the life of nuclear power all pretty much include breeder reactors (such as thorium reactors) and have unresolved fuel cycle problems. Fast breeder reactors are also illegal in the US owing to proliferation concerns. Their prototypes have also tended to melt down.
The new reactor being planned for Calvert Cliffs has an estimated price tag of $2.50/Watt for construction alone, though with federal loan guarranties included in the Senate Energy Bill, this price will likely rise substantially. The price compares poorly with wind and solar, both at about $1.30/watt to build, but with much less in the way of operating costs, and obviously no fuel or long term waste disposal costs.
The level of effort put into fusion has not really been that large. You hear about it, but compared to the Manhatten Project, out of which nuclear power came, it gets much less in the way of GDP. Renewables get even less than that. This was deliberate. The idea was to give it enough effort so that it would be ready when oil and coal ran out. The problem is that at the time, the growth in the use of coal and oil was not foreseen. So, fusion is actually right about on schedule. When it is here, there may be some trouble siting it since nuclear power plants squat on some of the better cooling resources and our storage in place policy for nuclear waste may keep these prime resources tied up for hundreds of years. But, wind was 20% of new generation in 2006 and is growing at 50% per year, while solar is growing at 30% per year and this should accelerate as the silicon purification bottleneck clears. So, fusion may enter a market that is already dominated by clean inexpensive power and thus find only niche applications in any case.
--
Go solar the easy way: http://mdsolar.blogspot.com/2007/01/slashdot-user
Solar and wind? (Score:2)
Why not solar? The Solar Constant, that's why. 1.367kW/m^2. Typical yield is closer to 1kW/m^2. Then some genius suggests that we cover an area roughly the size of Arizona with solar cells to generate all of the power. Riiiiiiiiight. "Just cover all of the roofs, and we'll be set!" Riiiiiiiiiight.
http://apod.nasa.gov/apod/ap970830.html [nasa.gov]
Those are the roofs. Added up, they might add up to Arizona. Not likely though. Now
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You are also incorrect on the durability of solar panels. They last 25 years at better than 80% rated capacity and will likely last 100 years at better than 40%.
On wind, current capacity is 74 thousand
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I was not commenting on their percentage output based on longevity. No solar panel has ever been 80% efficient as a percentage of the Solar Constant [wikipedia.org] . No panel will EVER get 100% of the Solar Constant. No energy transfer mechanism in the real world will ever be 100% efficient.
Nevada has regions that get 9 kWh per square meter of sunlight per day on average over a year, or 375 Watts per square meter of average power. At 20% efficiency you get 75 of those. So we just divide the 1.2 TW of energy we use that we calculated earlier by 75 W per square meter to get the number of square meters we need. Divided again by a million gives 16000 square kilometers. The square root of this, 126 km, gives the length of the edge of the square which is about 80 miles.
Okay, let's take a closer look together. You see that 20% reference? That does NOT mean the solar cells working at 20% of their capacity; that means that the solar panels are working at 20% of wh
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Nuclear power plants are not either 100% on or completely off. The reaction can be moderated to many shades of gray, just as the comments on your own blog mention. You are presenting a straw man: not accurately representing how the opposition works and then taking them to task using your own sketchy characterization.
Your second link deals with the benefits of decentralization. Once again, I have no argument with that. I am not against wind and solar use.
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Those are the roofs. Added up, they might add up to Arizona. Not likely though. Now imagine that you wanted to cover up Arizona with big pieces of paper, the whole state. I want you to imagine the scale of a project like that with just paper. Now I want you to reflect on the difficulty inherent with replacing all of that paper with silicon semiconductors that currently require clean rooms for manufacture.
Much better solutions [sfgate.com] are coming online. Like hydrogen-pr
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With
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But fusion does, however, produce a large amount of radioactive waste. Not through the products of the reaction. Through the byproducts of the high level of irradiation.
The difference is that fission radioactive byproducts are long lived. Fusion radioactive byproducts are extremely radioactive, but very short lived, and therefore easier to deal with
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Some of the main benefits of thorium reactors are that they vastly reduce the amount of waste, emit waste that has much shorter half-lives, and (here's the kicker) can eliminate existing stockpiles of plutonium and spent fuel.
Fusion does nothing to address the issue of existing nuclear material.
It's not an either-or deal; it's a measured "both."
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* Fuel for fusion can be extracted from water, including non-potable water. Fission requires Uranium & Thorium to be mined and transported, and your country might not have it. By the time the fuel runs out, our sun will be a red giant, so we should worry about escaping the solar system before doing any better than that.
* No weapons material generation (Thorium is in some respects similar here).
* Radioactive waste: there's a lot less of the stuff sticking around, and really no hig
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I don't know if that will ever happen. With most sources of energy, the fuel is unevenly spread around the globe. And being some small country that has a huge reserve of some kind of fuel will tend to mess your country up in the same way that people who inherit a lot of money (and never have to work a day in their lives) get messed up.
Trade doesn't always have to create political instability,
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--
Get clean energy: http://mdsolar.blogspot.com/2007/01/slashdot-users -selling-solar.html [blogspot.com]
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Get fusion on your roof: http://mdsolar.blogspot.com/2007/01/slashdot-user
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And beside that; the dictionary definition of "nuclear reactor" is out of date and is based on the science of the Thirties. A neutron gun capable of creating nuclear reactions might very well be described
Oh, great! (Score:5, Funny)
Stellarators have been around as an idea for years (Score:5, Insightful)
http://en.wikipedia.org/wiki/Stellarator [wikipedia.org]
Anyway, basically what I know about this is that stellarator designs avoids lots of the problems that are present in Tokamak - namely, degrading of the reaction chamber due to escaped neutrons. A fusion reactor using stellarator instead of Tokamak would, in effect, last forever since the material does not become radioactive.
Especially the Germans have been researching this stuff a lot, however, most of the big money is currently in Tokamak designs, including ITER. Which is kinda a shame - since we're not in the Manhattan Project-type "if you have 3 designs and think one of them might work, build all three, here's the money"-situation..so these nice ideas may only be developed further if Tokamak fails to become viable..
Re:Stellarators have been around as an idea for ye (Score:2)
Also according to those comments, the idea of fusing atoms is completely unproven.
I think I'm just going to give up on humanity.
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Sorry, but fusion works. It is completely proven as a physical mechanism -- look at the Sun! Look at the fusion reactors in which we've generated hundreds of megawatts of fusion power (not breakeven conditions); look at particle accelerators...
So, keep your faith in humanity; just because some ignorant asshat wants to blurt blatantly incorrect things like "water isn't wet" or "gravity doesn't work" doesn't mean it's true.
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But it doesn't seem like it's just a few ignorant asshats blurting blantantly incorrect things, it seems like it's most people. After all, look how many people go around saying evolution is false and the earth is 6000 years old. Even here on Slashdot, a geek haven, there's tons of them. No one understands, or even wants to understand basic science any more. I think we're headed into another Dark Ages.
Re:Stellarators have been around as an idea for ye (Score:2)
Re:Stellarators have been around as an idea for ye (Score:2)
So, where in the stellerator design does the unobtanium shielding goes that stops the neutrons?
This is a serious question. If you have [hot] fusion you have neutrons, and they have to go somewhere. Magnetic fields won't stop them.
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Doh! (Score:5, Informative)
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Why reinvent the wheel? (Score:5, Interesting)
1. Contain a plasma ball with high density for fusion reaction. Ball is much better than doughnut if you just can figure out a way to keep the plasma together.
2. Make a wall that is far enough away to not melt from this plasma ball to absorb heat/radiation to make power, and keep it close enough to get high enough energy density on its face.
3. Make the wall 1 ton/m^2 to protect the people outside
4. Use magnetic field outside plasma ball to contain radiation.
This seems like a tall order, and it is, but consider the sun/earth:
1. Gravity works great compared to magnetism.
2. Well, here on the earth, it is 1kW/m^2. That is much higher than the energy consumption in most cities. Should be good.
3. Our atmosphere stupid.
4. The earth again has a great magnetic field that protects us pretty well.
Bottom line: Why reinvent the wheel?
Re:Why reinvent the wheel? (Score:5, Informative)
This seems like the exact reason why basic physics should be mandatory in schools. Dear God. How exactly would a magnetic field contain neutral photons ? They will generate zero flux and will not interact with the field at all.
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The fact that protons are positive, electrons are negative, and neutrons are.. you know.. neutral and therefore not affected by magnetic fields.. yes, I learned that in about 6th grade.
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Regards,
Ross
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You know, 1/d^2 is sort of a problem when you are d close to me. (When d is is 1/500 AU).
And yes, I do know about the super-pure H2O and Cl- deep-mine tanks that monitor for neutrinos.
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And neutrons != photons....Though it wasnt until college Emag (Phys5 or 6 I think) that I learned all the math behind the em wave functions (yes, light IS an electro-MAGNETIC field/wave) that make all this stuff happen.
tm
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Please read post before commenting (Score:2)
Please reread parent post. Note: 1 ton/m^2 of mostly Nitrogen *and* magnetic field to protect people.
Life on earth has pretty much evolved around surviving radiation not caught by this protection. The physics is sound.
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There are also possible photon-magnetic field interactions though with a low coup
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E=mc^2 and for a photon, E=hc/l, 'l' is wavelenght and h is planck's constant, so
photon mass, m=h/(lc)
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Also, a photon's energy can be converted into mass via e=mc^2 (high energy gamma rays can spontaneously form stable particle/antiparticle pairs with actual mass). That possible "mass of conversion" can be expressed as the potential mass or equivalent mass of a photon.
Regards,
Ross
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-Gravitational_Lensing- [wikipedia.org]
(Astronomers are using it all the time these days)
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That's my understanding, but if that is shown to be incorrect, I'll be the first to admit I don't know what I'm talking abou
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Houston, we have a unit problem
Here ya go (Score:2)
http://www.google.com/search?hl=en&q=1+ton%2Fm%5E
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The sun starts by fusing hydrogen. (http://www.tim-thompson.com/fusion.html)
This first step happens on a huge timescale:
p + p --> d + e+ + nu 7.9 x 10^9 years
This only works out in the sun because it's a frickin huge ball of gas.
Terrestrial reactors will use DT fusion. The time it takes for this reaction to happen is not worth talking about.
And regarding the
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Actually, He3-He3 fusion (the last few steps in solar fusion) is substantially safer than DT fusion due to the minimal neutron flux. See wikipedia [wikipedia.org] for more information (it's the last reaction in the proton cycle where 2 He3 -> He4 + 2 H- + 12.86MeV). Not quite as much energy as D + T -> He4 + N + 17.6MeV, but still a respectable amount of energy and much less neutron damage to the reacto
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D+He3 fusion (and other aneutronic fusion, like p+B11) certainly is nice, but we're not going to get there anytime soon. Why? These fuels don't "burn" easily; the cross-sections for aneutronic fuels are lower than DT's, and peak at substantially higher temperatures. I suspect
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Your answer is "we should use the sun". Well done. Got any better methods than what we're using currently?
Magnetically confined plasma fusion reactors (Score:5, Informative)
* Physics of magnetically confined fusion [ipp.mpg.de] [pdf]
* The main principles of magnetic fusion [www-fusion...que.cea.fr]
* Magnetic fusion experiments at LANL [lanl.gov]
* High density magnetic fusion [ucsd.edu]
* Has a good bit on magnetic confinement [geocities.com]
* Can a magnetic field be used to contain plasma? [anl.gov]
* International Thermonuclear Experimental Reactor [iter.org]
* What's happening in fusion? [ieee.org]
* Design of magnetic fields for fusion experiments [columbia.edu] [pdf]
* Wikipedia article on the topic [wikipedia.org]
* Magnetized target fusion bibliography [lanl.gov]
* Plasma physics bibliography [wisc.edu]
* Databases for plasma physics [weizmann.ac.il]
* Plasma physics laboratories [pppl.gov]
* List of plasma physicists [wikipedia.org]
* Plasma on the internet [weizmann.ac.il]
somewhere over the rainbow (Score:2)
Practical uses of Stellarator technology are projected, of course, to be "just a few years off".
Mmhmm (Score:2)
But Stella Kowalski Is The Old Style Stella (Score:2)
"Stellarator" (Score:2, Funny)
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Nice News for Nerds but... (Score:2, Interesting)
Unless I'm wrong, the production of non-military nuclear reactor designs in the US for the last 30 years have been... zero. Unless you count the Galileo, Ulysses, and Cassini space probes. Call me when we upgrade all of our reactors from 1973 designs [wikipedia.org] to a much safer and cleane
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Drop the illusions... (Score:2)
Also look at this link: http://www.sandia.gov/media/z290.htm [sandia.gov]
"Stockpile stewardship" is not about solving our energy problems... Well, at least not peacefully... It's all about ensuring that the aging nukes will perform
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Question for physicists who work on plasma (Score:2)
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Short answer: because it's been proven to be physically impossible in any topology which can be mapped to a shpere since the 50's, at least if you're confining with magnetic fields. It has to do with their structure.
That's why all devices are topologically similar to that of a donut, be it like an inner-tube shape (tokamak), cored apple (spherical tokamak), or funny twisted kinky looking (stellarator).
The main difference between the tokamak and stellarator is where to supply the confining magnetic field.
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Still concave toward the plasma. (Score:3, Interesting)
(My take on that has been that even if passive geometries are unstable, if you can get it stable enough that instability growth occurs at no more than an HF rate you might be able to use an active system to finish the job of stabilizing the confinement. But that's a separate issue.)
It's published, not "up for peer review"... (Score:2)
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From the chasing your own tail dept. (Score:3, Insightful)