5 ms·

The real deal is here, from MIT: https://www.youtube.com/watch?v=KkpqA8yG9T4 https://www.youtube.com/watch?v=KkpqA8yG9T4 Apparently there was a recent breakthr

The real deal is here, from MIT: https://www.youtube.com/watch?v=KkpqA8yG9T4 https://www.youtube.com/watch?v=KkpqA8yG9T4 Apparently there was a recent breakthrough in superconductors, which allows significantly more current in the inductor coils while still maintaining superconductivity. This in turn allows for much stronger magnetic fields, hence tighter confinement of the plasma and therefore more fusion. A standard tokamak with these new superconductors should produce more energy out than energy in, and be a viable source of energy.

danbruc 9y ago
Apparently there was a recent breakthrough in superconductors [...] Recently in this case means mid 1980s. Is the ITER design really that old that they could not make use of YBCO superconductors?
- deleted 9y ago
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- deleted 9y ago
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- scythe 9y ago
  IIRC YBCO can't be feasibly made into wires. However new cuprates have been discovered which are less brittle: http://en.wikipedia.org/wiki/Bismuth_strontium_calcium_copper_oxide#Wires_and_tapes http://en.wikipedia.org/wiki/Bismuth_strontium_calcium_coppe...
  - danbruc 9y ago
    I am not an expert but according to Wikipedia BSCCO is not suitable for high magnetic field strengths. In the video - which I only skimmed - the main point seems to be that they can now build vastly smaller fusion reactors because now super conductors supporting higher fields strengths are available and the energy density of a fusion reactor scales with the fifth power of the magnetic field strength. They also specifically mention rare earths which does not match BSCCO which were, last but not least, also discovered in the late 1980s.
    - mng2 9y ago
      The biggest question in my mind about the ARC proposal is how well these new superconductors stand up to radiation. This is a concern for ITER as well, which uses more traditional superconductors. The ARC team is looking into it, but I'm going to remain unenthusiastic about ARC until they've really proven out the concept.
      - Obi_Juan_Kenobi 9y ago
        Around 33 minutes into the presentation he does address radiation briefly, noting that it's favorable because most of the issues relate to the ceramic insulators in traditional SC magnets. In their design, the steel structural component of the tape serves as the insulator; they just wind up the SC tape and the current travels along that 1um SC layer. More generally, the demountable coils suggests that designs could be made where the magnets are replaceable with some degree of economy.
- IshKebab 9y ago
  The recent breakthrough is high current YBCO tape, not YBCO itself. https://en.wikipedia.org/wiki/Superconducting_wire#Coated_superconductor_tape_or_wire https://en.wikipedia.org/wiki/Superconducting_wire#Coated_su...
JumpCrisscross 9y ago
Eye opener is the chart at 18:03: "from 1970 to 1995, [fusion] power and energy increased much faster than computing power (Moore's Law)" [1]. Magnetic-confinement fusion stalled, according to Dr. Whyte, because to get more power (and efficiency) we need stronger fields. To get stronger fields we needed bigger magnets. To support bigger magnets one needs bigger structures. Big magnets and big structures will absorb more magnetic and neutron flux; that increases maintenance frequency, complexity and cost. Better superconductors let us get stronger fields without bigger magnets. That changes the cost function. [1] https://youtu.be/KkpqA8yG9T4?t=18m3s https://youtu.be/KkpqA8yG9T4?t=18m3s
- api 9y ago
  The lack of investment in this field is absolutely ludicrous given the potential payoff. I suspect some amount of lobbying by entrenched power and fuel interests that would be rendered obsolete, but I think more blame can be placed on that awful meme that brainwashed a generation of scientists and engineers into dismissing fusion as a boondoggle: "Fusion energy is 20 years away and always will be." This shows how much damage a superficial catchy meme can do if it manages to slip in and override more nuanced and informed thinking. It's why I distrust catchy sloganish rules in other fields too, such as "premature optimization is the root of all evil" (leads to erooM's law in software) or "never roll your own cryptography" (discourages people from learning about how to create secure systems), etc.
  - Neutrion 9y ago
    exactly, these slogan almost look like a doctrination campaign. but this is off topic.
  - Retric 9y ago
    20 years ago they said "Fusion energy is 50 years away and always will be." Soon enough it's going to drop to "Fusion energy is 5 years away and always will be." Which is just silly.
    - BrandonMarc 9y ago
tudelo 9y ago
Preface: I know nothing about this. How can it "produce more energy out than energy in"? I don't know if I am not aware of what you mean by that, but that doesn't seem possible?
- mark-r 9y ago
  That's the whole point of fusion: it produces energy. But you can't do anything practical with it until you have a reactor that produces more power than it takes to run.
  - gryfft 9y ago
    To clarify, it produces energy equal to the difference between the mass of the fuel and the mass of the final byproduct multiplied times the speed of light squared. Energy and mass are conserved, but some mass is converted into useful energy. Doing so in a way that produces sufficient energy to sustain the fusion reaction without creating an uncontrolled reaction ("boom") is the trick that always seems to be 30 years away.
    - orclev 9y ago
      > Doing so in a way that produces sufficient energy to sustain the fusion reaction without creating an uncontrolled reaction ("boom") is the trick that always seems to be 30 years away. Uh, no, not really, a run away fusion reaction has never really been a concern. In fact, that's one of the biggest advantages of a fusion reactor vs. a fission reactor. Fission is a self-sustaining reaction, once it starts you have to work to stop it (via injecting a mediator to interfere in the fission reaction), where as fusion requires constant energy input in order to maintain the reaction. The part that "always seems to be 30 years away", is achieving a fusion reaction that produces more energy than it takes to maintain (allowing some of the output energy to be siphoned off to maintain the reaction). There have been a number of techniques attempted to achieve this with the holy grail being so called "cold" fusion, where cold is defined in this context as something less than the surface temperature of the sun. It sounds like the ultimate solution to the problem though is simply better magnets, not cold fusion at all. Assuming this pans out, the real thing needed to make this viable as something other than a novelty is how much more efficient the reaction can be made. After all, if the output energy is just barely over the input energy you'd need to scale out to ridiculous extremes to produce enough usable energy, but if it's a significant amount higher then that makes more modest size plants viable.
SEJeff 9y ago
But have they made any strides in manufacturing tokamaks, or are they still insanely difficult to build? This superconductor breakthrough also seems relevant to Stellarators such as Germany's new(ish) Wendelstein 7x: https://en.wikipedia.org/wiki/Wendelstein_7-X https://en.wikipedia.org/wiki/Wendelstein_7-X
- Nomentatus 9y ago
  Well, this is the stride. If I remember (I watched the video weeks ago) building them smaller, with the steel part of the tape doing a lot of the work means you can build and swap modules to create a far smaller tokamok or stellerator that you can immerse. The same topologies can and would be used - perhaps with more stable containment (for reasons I forget.)

danbruc 9y ago

Apparently there was a recent breakthrough in superconductors [...] Recently in this case means mid 1980s. Is the ITER design really that old that they could not make use of YBCO superconductors?

deleted 9y ago
[deleted]
deleted 9y ago
[deleted]
scythe 9y ago
IIRC YBCO can't be feasibly made into wires. However new cuprates have been discovered which are less brittle: http://en.wikipedia.org/wiki/Bismuth_strontium_calcium_copper_oxide#Wires_and_tapes http://en.wikipedia.org/wiki/Bismuth_strontium_calcium_coppe...
- danbruc 9y ago
  I am not an expert but according to Wikipedia BSCCO is not suitable for high magnetic field strengths. In the video - which I only skimmed - the main point seems to be that they can now build vastly smaller fusion reactors because now super conductors supporting higher fields strengths are available and the energy density of a fusion reactor scales with the fifth power of the magnetic field strength. They also specifically mention rare earths which does not match BSCCO which were, last but not least, also discovered in the late 1980s.
  - mng2 9y ago
    The biggest question in my mind about the ARC proposal is how well these new superconductors stand up to radiation. This is a concern for ITER as well, which uses more traditional superconductors. The ARC team is looking into it, but I'm going to remain unenthusiastic about ARC until they've really proven out the concept.
    - Obi_Juan_Kenobi 9y ago
      Around 33 minutes into the presentation he does address radiation briefly, noting that it's favorable because most of the issues relate to the ceramic insulators in traditional SC magnets. In their design, the steel structural component of the tape serves as the insulator; they just wind up the SC tape and the current travels along that 1um SC layer. More generally, the demountable coils suggests that designs could be made where the magnets are replaceable with some degree of economy.
IshKebab 9y ago
The recent breakthrough is high current YBCO tape, not YBCO itself. https://en.wikipedia.org/wiki/Superconducting_wire#Coated_superconductor_tape_or_wire https://en.wikipedia.org/wiki/Superconducting_wire#Coated_su...

JumpCrisscross 9y ago

Eye opener is the chart at 18:03: "from 1970 to 1995, [fusion] power and energy increased much faster than computing power (Moore's Law)" [1]. Magnetic-confinement fusion stalled, according to Dr. Whyte, because to get more power (and efficiency) we need stronger fields. To get stronger fields we needed bigger magnets. To support bigger magnets one needs bigger structures. Big magnets and big structures will absorb more magnetic and neutron flux; that increases maintenance frequency, complexity and cost. Better superconductors let us get stronger fields without bigger magnets. That changes the cost function. [1] https://youtu.be/KkpqA8yG9T4?t=18m3s https://youtu.be/KkpqA8yG9T4?t=18m3s

api 9y ago
The lack of investment in this field is absolutely ludicrous given the potential payoff. I suspect some amount of lobbying by entrenched power and fuel interests that would be rendered obsolete, but I think more blame can be placed on that awful meme that brainwashed a generation of scientists and engineers into dismissing fusion as a boondoggle: "Fusion energy is 20 years away and always will be." This shows how much damage a superficial catchy meme can do if it manages to slip in and override more nuanced and informed thinking. It's why I distrust catchy sloganish rules in other fields too, such as "premature optimization is the root of all evil" (leads to erooM's law in software) or "never roll your own cryptography" (discourages people from learning about how to create secure systems), etc.
- Neutrion 9y ago
  exactly, these slogan almost look like a doctrination campaign. but this is off topic.
- Retric 9y ago
  20 years ago they said "Fusion energy is 50 years away and always will be." Soon enough it's going to drop to "Fusion energy is 5 years away and always will be." Which is just silly.
  - BrandonMarc 9y ago

tudelo 9y ago

Preface: I know nothing about this. How can it "produce more energy out than energy in"? I don't know if I am not aware of what you mean by that, but that doesn't seem possible?

mark-r 9y ago
That's the whole point of fusion: it produces energy. But you can't do anything practical with it until you have a reactor that produces more power than it takes to run.
- gryfft 9y ago
  To clarify, it produces energy equal to the difference between the mass of the fuel and the mass of the final byproduct multiplied times the speed of light squared. Energy and mass are conserved, but some mass is converted into useful energy. Doing so in a way that produces sufficient energy to sustain the fusion reaction without creating an uncontrolled reaction ("boom") is the trick that always seems to be 30 years away.
  - orclev 9y ago
    > Doing so in a way that produces sufficient energy to sustain the fusion reaction without creating an uncontrolled reaction ("boom") is the trick that always seems to be 30 years away. Uh, no, not really, a run away fusion reaction has never really been a concern. In fact, that's one of the biggest advantages of a fusion reactor vs. a fission reactor. Fission is a self-sustaining reaction, once it starts you have to work to stop it (via injecting a mediator to interfere in the fission reaction), where as fusion requires constant energy input in order to maintain the reaction. The part that "always seems to be 30 years away", is achieving a fusion reaction that produces more energy than it takes to maintain (allowing some of the output energy to be siphoned off to maintain the reaction). There have been a number of techniques attempted to achieve this with the holy grail being so called "cold" fusion, where cold is defined in this context as something less than the surface temperature of the sun. It sounds like the ultimate solution to the problem though is simply better magnets, not cold fusion at all. Assuming this pans out, the real thing needed to make this viable as something other than a novelty is how much more efficient the reaction can be made. After all, if the output energy is just barely over the input energy you'd need to scale out to ridiculous extremes to produce enough usable energy, but if it's a significant amount higher then that makes more modest size plants viable.

SEJeff 9y ago

But have they made any strides in manufacturing tokamaks, or are they still insanely difficult to build? This superconductor breakthrough also seems relevant to Stellarators such as Germany's new(ish) Wendelstein 7x: https://en.wikipedia.org/wiki/Wendelstein_7-X https://en.wikipedia.org/wiki/Wendelstein_7-X

Nomentatus 9y ago
Well, this is the stride. If I remember (I watched the video weeks ago) building them smaller, with the steel part of the tape doing a lot of the work means you can build and swap modules to create a far smaller tokamok or stellerator that you can immerse. The same topologies can and would be used - perhaps with more stable containment (for reasons I forget.)