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Comments: 171 +-   New 'Stellarator' Design for Fusion Reactors on Friday August 10 2007, @05:40PM

Posted by Zonk on Friday August 10 2007, @05:40PM
from the less-whoosh-boom-for-your-money dept.
power
science
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."
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Submission: New 'Stellarator' Design for Fusion Reactors by eldavojohn (898314)
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  • Princeton 1951 called... (Score:2, Insightful)

    by Anonymous Coward
    ...they want credit.

  • If they used... (Score:4, Funny)

    by jd (1658) <imipak.yahoo@com> on Friday August 10 2007, @05:45PM (#20190079) Homepage Journal
    ...Axl symmetry, they could produce something that was violently unstable but produced vast amounts of marketable energy and money.

      • Re:If they used... (Score:4, Funny)

        by heinousjay (683506) on Friday August 10 2007, @06:51PM (#20190755) Journal
        I hope you're serious, I take great solace in knowing the world is full of crazy people.

        • Re: (Score:3, Interesting)

          by jd (1658)
          I don't - they keep getting elected. What we don't need right now is more crazies in power. What we need is someone so totally and utterly insane, they'll spend two or three trillion dollars a year on getting a full-scale fusion reactor built and operational before they get kicked out of office or shot. Yes, there are many unsolved problems, but we're running a little low on time and researchers are too busy on corner cases that might never happen in a real reactor under normal conditions. Building a live s

          • Re:If they used... (Score:5, Insightful)

            by The_Wilschon (782534) on Saturday August 11 2007, @01:08AM (#20193075) Homepage
            Blast radius my foot. A fusion reactor is immensely safer than a fission reactor. Furthermore, fission reactors are really very safe (far safer than, say, oil refineries). Even Chernobyl was primarily a /chemical/ explosion (although caused by problems with the reactor), which happened to scatter radioactive debris over half the globe. A chemical explosion at a fusion plant would scatter hydrogen. Oh boy. Even the unstable isotopes of hydrogen are still light enough that they would float to the top of the atmosphere and escape into space in very little time. A fusion reactor is not a controlled H-bomb. Unlike a fission reactor, which requires a carefully tuned reaction to walk the knife's edge between dying out and going critical, the hard part with fusion is keeping it going. Fusion is very fussy. If the density, and the temperature, and the composition of the plasma are not just exactly right, then reaction dies out in a fraction of a second, the time it takes to exhaust the really tiny amount of fuel that is available to it at any given time. To keep it going, you have to keep feeding it more fuel, as well as carefully tuning things. If there were even a very very tiny explosion, the worst it would do is damage the devices tuning the plasma's parameters, and then the reaction would die out. Even if the fuel feeders went crazy and started flooding hydrogen in as fast as they could, it would still just die out. There is no way that the reactor, even in an undamaged state, could bring enough hydrogen to the needed density and temperature quickly enough to cause a thermonuclear explosion even on the scale of a pipe bomb. So, I say, blast radius my foot, unless you want to compress the researchers down very very small and put them inside the plasma itself.

            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.

      • Re: (Score:3, Insightful)

        by joto (134244)

        We already can get ALL the energy we need from renewable sources

        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.

        a bunch of overblown ass

  • Stellarators aren't new (Score:4, Informative)

    by Anonymous Coward on Friday August 10 2007, @05:53PM (#20190141)
    The summary makes it sound like stellarators are something novel, which they are not. Research has been going on for decades, most notably with the German Wendelstein experimental reactors.

    • Re:Stellarators aren't new (Score:5, Informative)

      by iamlucky13 (795185) on Friday August 10 2007, @07:01PM (#20190853)
      In fact, the stellarator design is almost as old as the Tokamak design. The first one was built in 1951.

      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?"

  • input-output (Score:3)

    by polar red (215081) on Friday August 10 2007, @05:53PM (#20190145)

    Like other forms of containment this does require energy itself
    I find it weird that the amount of energy needed to contain, is less than the energy contained in the plasma. Can anyone explain this ?

    • Re:input-output (Score:4, Insightful)

      by Paul Pierce (739303) on Friday August 10 2007, @06:01PM (#20190251) Homepage

      Like other forms of containment this does require energy itself
      I find it weird that the amount of energy needed to contain, is less than the energy contained in the plasma. Can anyone explain this ?

      Picture Chinese handcuffs

    • Re: (Score:2, Interesting)

      by thanatos_x (1086171)
      It's intrinsically harder to do useful work that raw work, just like it's easier to destroy than create....

      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)

      by iamlucky13 (795185) on Friday August 10 2007, @07:21PM (#20191035)
      Well, I'm not a plasma physicist, so I'm not intimately familiar with all the details, but one thing that jumps out at me right away is the distinction between energy and power.

      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.

    • Re:input-output (Score:5, Informative)

      by counterfriction (934292) on Friday August 10 2007, @07:26PM (#20191067) Homepage
      "Energy" in the context of containing a plasma is actually work. They have the same units, so they're like exchangeable currencies (i.e. some energy will buy you work, and some negative work will buy you energy)
      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.

  • Huh... (Score:3, Funny)

    by Greyfox (87712) on Friday August 10 2007, @05:55PM (#20190163) Homepage Journal
    SCO Loses and they figure out fusion* on the same day. Coincidence? I think NOT!

    * 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)

    by Bombula (670389) on Friday August 10 2007, @06:00PM (#20190237)
    I was reading about thorium reactors recently. Seems like that's much closer to being rolled out, and its developers are claiming it solves a lot of the problems with existing reactors: it's more stable because thorium reactions don't chain the same way, it doesn't produce waste or plutonium, it can actually burn up other waste - including plutonium, and it can be used in some types of existing reactors (there are trials in Russian reactors right now).

    Does anyone know any more about this?

    • Thorium good, but if possible, fusion even better.

      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)

        by Bombula (670389) on Friday August 10 2007, @08:03PM (#20191269)
        Thorium good, but if possible, fusion even better.

        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)

          by mdsolar (1045926) on Friday August 10 2007, @11:15PM (#20192513) Homepage Journal
          Solar and wind power fit the bill of being clean and local. A lot of our nuclear fuel these days comes from Russian weapons stockpiles. But the process of diluting it back down from weapons grade to fuel grade is not going all that well. In an accident in Tennessee last year that was covered up until congress stepped in, the plant managers thought that a big spill of highly enriched uranium soulution, enough to cause the kind of accident that killed 2 people in Japan 1999, was natural uranium. There were two places where the spill might have accumulated and cause criticality. That is pretty poor materials control if you don't know what it is that you are working with.

          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-users -selling-solar.html [blogspot.com]

        • Re: (Score:3, Interesting)

          by adrianmonk (890071)

          we need clean, non-polluting power that doesn't ultimately come from politically volatile parts of the world.

          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,

          • Re: (Score:3, Informative)

            by barawn (25691)
            That's not exactly true. The ideal output of most fusion cycles is stable. You get side production of tritium and a few other radioactive isotopes, though.

            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

          • Re: (Score:3, Informative)

            by rossifer (581396)
            Almost all of the waste from a molten salt Thorium fuel cycle reactor has a half life of 30 years or less (total storage of 300 years and it's as clean as the thorium ore it came from). Also, the mass/volume of the waste to be stored is substantially lower than a light water reactor because you can continuously mechanically and chemically extract the waste from the liquid fuel. With a solid fuel reactor, the waste is physically tied to 90% of the still-good U235 and the now damaged ceramic that makes up t
      • You want to be careful with that stuff. There was a boy who built a breeder in his mother's shed in the ninties using thorium. He was arrested again at the beginning of this month for stealing smoke detectors. He does not look so healthy in his mugshot: http://freep.com/apps/pbcs.dll/article?AID=/20070 8 03/NEWS04/70803062 [freep.com]. Sad story. There just isn't any such thing as clean fission. It makes a mess every time.
        --
        Get clean energy: http://mdsolar.blogspot.com/2007/01/slashdot-users -selling-solar.html [blogspot.com]

  • Oh, great! (Score:5, Funny)

    by Sloppy (14984) on Friday August 10 2007, @06:05PM (#20190297) Homepage Journal
    I just bought a fusion reactor that uses the old design!

  • Stellarators have been around as an idea for years (Score:5, Insightful)

    by Zarhan (415465) on Friday August 10 2007, @06:13PM (#20190391)
    ...and as prototypes too.

    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..
    • According to the comments at the end of the physorg article, that's not true.

      Also according to those comments, the idea of fusing atoms is completely unproven.

      I think I'm just going to give up on humanity.

    • Right. The slashdot summary is faulty: What's new isn't the stellerator design itself, but a new coil configuration for a stellerator. The new configuration "generating an external magnetic field designed to prevent the plasma from deteriorating", although I'm not familiar enough with stellerators to know how much of a problem this was in previous designs.

    • 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.

      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.

  • Doh! (Score:5, Informative)

    by the eric conspiracy (20178) on Friday August 10 2007, @06:15PM (#20190407)
    A stellarator is not a new design. The first examples were built here [pppl.gov] in 1951.

  • Why reinvent the wheel? (Score:5, Interesting)

    by viking80 (697716) on Friday August 10 2007, @06:21PM (#20190485) Journal
    Design parameters for fusion reactor:
    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)

      by OeLeWaPpErKe (412765) on Friday August 10 2007, @06:32PM (#20190587) Homepage
      4. Use magnetic field outside plasma ball to contain radiation

      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.

      • 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.
        Clearly adding a flux capacitor to the magnetic field generator is necessary to add flux to the contained photons.

      • Re: (Score:3, Insightful)

        by lawpoop (604919)

        This seems like the exact reason why basic physics should be mandatory in schools.
        Okay...

        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.
        Is this the kind of basic physics that the average student would understand in their mandatory class?

          • We covered that at the high school level (neutrons = no charge). What did your physics class cover?

            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

          • Re: (Score:3, Informative)

            by rossifer (581396)
            Actually, you'd be correct if you were to say that neutrons are not affected by electric fields. But neutrons are fermions with magnetic spin and are affected by (and can be moved around with) magnetic fields, so...

            Regards,
            Ross
      • I took physics in high school and I still have no idea what you're talking about.

      • 4. Use magnetic field outside plasma ball to contain radiation

        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.

        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.

      • Not all radiation is made of photons. Specifically, alpha rays are made of helium nuclei (and are therefore positive) and beta rays are made of electrons (and are therefore negative).

    • 3. Make the wall 1 ton/m^2 to protect the people outside

      Houston, we have a unit problem

  • "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.


    Practical uses of Stellarator technology are projected, of course, to be "just a few years off".
  • Quasineutrality? Quasi-likely-to-work-in-the-real-world more like. :P
  • Refrigerator full of Stella?
  • If society won't even accept safe fission designs, what makes you think we will ever get far more powerful fusion reactors built? I think the largest problem now is the culture of misinformation and fear, not the problem of technology.

    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

  • Still concave toward the plasma. (Score:3, Interesting)

    by Ungrounded Lightning (62228) on Friday August 10 2007, @10:55PM (#20192379) Journal
    I seem to recall one of Bussard's points in his talk Should Google Go Nuclear? was that plasma confinement by magnetic fields is inherently unstable when the confinement is concave toward the plasma, no matter how you twist them. Thus Stellarators, Tokamaks, etc. are (in his opinion) doomed. (And that's why his design is conVEX toward the plasma.) [google.com]

    (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.)
      • For the $1,000,000,000,000 Monkey Boy will spend in Iraq we could have put solar collectors on every home in America for free. So they finally figure out how to make fusion work. Energy will still be monopolized by the power companies and you'll still be paying through the nose. And if you try to do anything about it they'll call you an enemy combatant and send you to Guantanamo. There is no technological fix. There is only a political fix.
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