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Fusion's been occurring in other reactor designs since the 50's -- just not specifically in this particular reactor. High School kids have achieved fusion in th

Fusion's been occurring in other reactor designs since the 50's -- just not specifically in this particular reactor. High School kids have achieved fusion in their basement with Farnsworth Fusor type designs. It's not especially hard. Breakeven, though, is a lot tougher.

Retric 17y ago
We have passed "break even" conditions in a reactor for D-T for a few seconds. The real test is getting useful amounts of net energy generation which requires about 5x break even for several minutes. IMO, ITER's design should get to that point, but I don't think fusion is going to cost less than solar let alone coal for a long time. PS: Using lasers to create fusion has always been more about simulating bombs than it was creating useful amounts of energy.
- DaniFong 17y ago
  You have achieve breakeven more broadly -- over the entire pulse, or over the electricity you pull from the grid, or perhaps most properly, including all of the material and labor costs as compared to just taking heat from the fusion reactor in the sky with wind turbines and solar collectors. As for the simulation of bombs vs power, I think it depends on who you ask; scientists or DOE project managers? It's interesting, after having left a PhD program in plasma physics (for fusion power,) I have a very different sense of the commercially plausible. All we're really using the fusion for is to create heat, and there are many ways to get heat inexpensively (solar, geothermal, coal, natural gas) that don't involve temperatures of hundreds of millions of degrees, that don't require superconducting coils, liquid helium cooling systems, ultra-high precision machined tungsten tiles, structural materials that are vaguely defined, completely unsourced, untested at the correct neutron fluxes, and rely upon rare earth elements, liquid lithium systems from which we're supposed to do tritium recovery (lithium is really reactive, tritium bubbles up and is explosive and diffuses through walls and embrittles them), liquid lithium walls on the inside of the chamber; high vacuum vacuum pumps, giant particle beams and incredibly non-linear and poorly understood science. You're comparing that to coal and mirrors and holes drilled in the ground and wind, all of which ultimately go into some kind of turbine (which is half or most of the expense!) The benefit of fusion just doesn't seem worth it for anything other than military applications or interstellar spacecraft. And really, we've got a lot to worry about before then...
  - Retric 17y ago
    As I recall the actual limitations where two fold, it's a research device so they did not want the extra radiation produced from an actual DT reaction so they stuck with DD. And it was cheaper to build it as a pulsed device and let it cool down, vs having an active cooling system. From what I can tell the problem over the last 25 years with fusion is people keep saying what is the least amount of money we can spend and still make something useful. But, actually building a fusion reactor costs ~20 billion so we have been stuck prototypes when we need to shoot for the moon. EDIT: Taking JET's design (http://en.wikipedia.org/wiki/Joint_European_Torus http://en.wikipedia.org/wiki/Joint_European_Torus) and building a 10GW reactor would actually be easier than trying to build a 1GW reactor with the same basic design. Also http://en.wikipedia.org/wiki/JT-60 http://en.wikipedia.org/wiki/JT-60 "During deuterium (D–D fuel) plasma experiments in 1998 plasma conditions were achieved which would, if the D–D fuel were replaced with a 1:1 mix of deuterium and tritium (D–T fuel), have exceeded break-even"
    - DaniFong 17y ago
      I would like to argue that prototypes have been what's called for. We don't even have a clear idea of what a commercial fusion reactor would look like. The cooling and tritium production issues, the structural materials, and the lifetimes required of the super cooling and superconducting systems, are massive problems that haven't really been solved yet. It's possible that replacing D-D with D-T would have yielded break-even for a few seconds, (I've heard that claim before too) but I'm very skeptical; increasing the internal heat generation is sure to change the plasma conditions: for example, there would be a lot of adiabatic expansion, which, even restrained against the tokamak fields, is liable to have a variety of unstable modes.
      - Retric 17y ago
        I feel that with a modular design that includes remote handling capability you could test things out a lot faster on a full scale device. As to internal heating issues, I don't think there is much problem extrapolating from Q0.7 at JET to Q1.2 at JT-60. Large Plasma devices are "the sexy" but IMO it's just another engineering problem at this point. And you don't design large scale power plants to sit at the outer edge of their capabilities 24x7. So yes, the highest energy pulses are unable after a few seconds, but we have built steady state fusion reactors they just operate further from their limits. PS: Finding T is a problem, but "just build it bigger" and suddenly D-D (or 75%D - 25%T etc) becomes reasonable. Edit: I am suggesting building building something with 4x ITER's budget which should give you ~8x the plasma volume and a lower surface area to volume ratio etc. We can also pump of the field strength etc. But you are limited to how much heat the wall can take so the plasma conditions don't need to be as efficient.

Retric 17y ago

We have passed "break even" conditions in a reactor for D-T for a few seconds. The real test is getting useful amounts of net energy generation which requires about 5x break even for several minutes. IMO, ITER's design should get to that point, but I don't think fusion is going to cost less than solar let alone coal for a long time. PS: Using lasers to create fusion has always been more about simulating bombs than it was creating useful amounts of energy.

DaniFong 17y ago
You have achieve breakeven more broadly -- over the entire pulse, or over the electricity you pull from the grid, or perhaps most properly, including all of the material and labor costs as compared to just taking heat from the fusion reactor in the sky with wind turbines and solar collectors. As for the simulation of bombs vs power, I think it depends on who you ask; scientists or DOE project managers? It's interesting, after having left a PhD program in plasma physics (for fusion power,) I have a very different sense of the commercially plausible. All we're really using the fusion for is to create heat, and there are many ways to get heat inexpensively (solar, geothermal, coal, natural gas) that don't involve temperatures of hundreds of millions of degrees, that don't require superconducting coils, liquid helium cooling systems, ultra-high precision machined tungsten tiles, structural materials that are vaguely defined, completely unsourced, untested at the correct neutron fluxes, and rely upon rare earth elements, liquid lithium systems from which we're supposed to do tritium recovery (lithium is really reactive, tritium bubbles up and is explosive and diffuses through walls and embrittles them), liquid lithium walls on the inside of the chamber; high vacuum vacuum pumps, giant particle beams and incredibly non-linear and poorly understood science. You're comparing that to coal and mirrors and holes drilled in the ground and wind, all of which ultimately go into some kind of turbine (which is half or most of the expense!) The benefit of fusion just doesn't seem worth it for anything other than military applications or interstellar spacecraft. And really, we've got a lot to worry about before then...
- Retric 17y ago
  As I recall the actual limitations where two fold, it's a research device so they did not want the extra radiation produced from an actual DT reaction so they stuck with DD. And it was cheaper to build it as a pulsed device and let it cool down, vs having an active cooling system. From what I can tell the problem over the last 25 years with fusion is people keep saying what is the least amount of money we can spend and still make something useful. But, actually building a fusion reactor costs ~20 billion so we have been stuck prototypes when we need to shoot for the moon. EDIT: Taking JET's design (http://en.wikipedia.org/wiki/Joint_European_Torus http://en.wikipedia.org/wiki/Joint_European_Torus) and building a 10GW reactor would actually be easier than trying to build a 1GW reactor with the same basic design. Also http://en.wikipedia.org/wiki/JT-60 http://en.wikipedia.org/wiki/JT-60 "During deuterium (D–D fuel) plasma experiments in 1998 plasma conditions were achieved which would, if the D–D fuel were replaced with a 1:1 mix of deuterium and tritium (D–T fuel), have exceeded break-even"
  - DaniFong 17y ago
    I would like to argue that prototypes have been what's called for. We don't even have a clear idea of what a commercial fusion reactor would look like. The cooling and tritium production issues, the structural materials, and the lifetimes required of the super cooling and superconducting systems, are massive problems that haven't really been solved yet. It's possible that replacing D-D with D-T would have yielded break-even for a few seconds, (I've heard that claim before too) but I'm very skeptical; increasing the internal heat generation is sure to change the plasma conditions: for example, there would be a lot of adiabatic expansion, which, even restrained against the tokamak fields, is liable to have a variety of unstable modes.
    - Retric 17y ago
      I feel that with a modular design that includes remote handling capability you could test things out a lot faster on a full scale device. As to internal heating issues, I don't think there is much problem extrapolating from Q0.7 at JET to Q1.2 at JT-60. Large Plasma devices are "the sexy" but IMO it's just another engineering problem at this point. And you don't design large scale power plants to sit at the outer edge of their capabilities 24x7. So yes, the highest energy pulses are unable after a few seconds, but we have built steady state fusion reactors they just operate further from their limits. PS: Finding T is a problem, but "just build it bigger" and suddenly D-D (or 75%D - 25%T etc) becomes reasonable. Edit: I am suggesting building building something with 4x ITER's budget which should give you ~8x the plasma volume and a lower surface area to volume ratio etc. We can also pump of the field strength etc. But you are limited to how much heat the wall can take so the plasma conditions don't need to be as efficient.