4 ms·

Laser fusion put on slow burn

30 points by ananyob 14y ago

eggoa 14y ago
Relevant graph: http://commons.wikimedia.org/wiki/File:U.S._historical_fusion_budget_vs._1976_ERDA_plan.png http://commons.wikimedia.org/wiki/File:U.S._historical_fusio...
- Flenser 14y ago
  Here's the paper the graph refers to. The original graph is on page 12: http://fire.pppl.gov/us_fusion_plan_1976.pdf http://fire.pppl.gov/us_fusion_plan_1976.pdf
- simba-hiiipower 14y ago
  wow, that’s pretty sad. the 'moderate' path would have required an average expenditure of ~$2.5 billion a year, and projected the completion of a reactor by 2005. a pretty small investment when you consider the size of the federal budget [1] and where most of the funding goes. even more sad, when considering the likelihood that many graphs relating to other potentially transformative technologies probably look much the same.. [1] http://en.wikipedia.org/wiki/Expenditures_in_the_United_States_federal_budget http://en.wikipedia.org/wiki/Expenditures_in_the_United_Stat...
  - jerf 14y ago
    Uh... I would not take that graph as some sort of gospel. The truth is that even now we do not have an effective known path to economically viable fusion power generation, and if nothing else our computer simulations are indescribably better than anything they had in the late 70s. Had we blown billions more in the 80s, we probably would simply have blown billions more in the 80s and still have no fusion today.
    - simba-hiiipower 14y ago
      that may be true, but getting it (or any new technology for that matter) to the point where it’d be economically viable requires an investment at some point.. and ‘blowing’ those billions in the 80s may very-well not have paid-off with economically viable fusion power today, but i highly doubt it would have left us with nothing to show for it.
      - jerf 14y ago
        We don't really have a hell of a lot to show for what we have spent. Non-zero, sure, but a lot of the lessons we learned could certainly have been learned for a lot more cheaply if we hadn't tried to leap to the end of the process with grandiose projects built more on hope than science.
  - throwit1979 14y ago
    $2.5B is roughly on par with the combined 2012 salaries of all NFL teams( $90MM - $118MM per team, at the cap ). Which is as it should be, since football is far more important to humanity than something as silly as cheap, safe, and clean energy.
- danielweber 14y ago
  One thing I take from this graph is that doubling fusion funding would still leave us at "fusion never", so we shouldn't bother doubling it. :(
ck2 14y ago
to help weapons scientists to care for the ageing US nuclear stockpile Simulating explosions helps determine maintenance for nuclear warheads? I would bet they were more likely trying to make a "nuclear" weapon without radiation/fallout and failed. I wonder what the world would be like with really cheap power though - I'd like to think a better place to live but more likely there would be a lot more war since the energy to do it would then be cheap.
- mchouza 14y ago
  Simulating explosions helps determine maintenance for nuclear warheads? It's not completely unreasonable: they need to validate the computational models that are used to check if an aged nuclear weapon will explode.
- kd5bjo 14y ago
  Second order effects can be quite surprising: as gasoline replaced whale oil as a fuel source, it also increased the demand for cars. This accelerated the practice of whaling because whale oil remained extremely desirable as the lubricant inside transmissions.
- Someone 14y ago
  One of the things with maintenance is that, although you do not want to use your them, you must make sure that your warheads work if you ever need them. The traditional and easiest way of doing that is to frequently build new warheads, and test explode the older ones. That is expensive and, nowadays, forbidden/frowned upon (I think the test ban treaty hasn't been ratified) So, one stops building new ones and ends up with thirty+ year old warheads. The radioactive materials inside them have aged, steel may have become brittle, etc. To ascertain whether these devices still work, tests are needed. You could do them on the devices themselves, but it is easier and cheaper to do an experiment with a few grams of radioactive materials than to work with a kg or so from a warhead (all IIRC; corrections welcome)
- ChuckMcM 14y ago
  "Simulating explosions helps determine maintenance for nuclear warheads?" Yes. Radioactive material is, by definition, slowly becoming non-radioactive by decaying into other atoms. You can think of those other atoms as 'contaminants' in your plutonium soup. What this means is if you create a nuclear warhead, and put it on the shelf, if you did nothing you would have a very sophisticated box holding some lead. But long before that it stops working as a nuclear warhead. So what you do is you take put one on the shelf in the lab and you sample it periodically to see how its content has changed, and run your simulations to see if plutonium or uranium with those makeups would still work within the boundaries of the device, and you try to test it periodically under conditions that simulate, as much as possible, an actual explosion. They used to do this at the test site, basically explode one warhead from a batch every 2 - 3 years to insure they still worked. But they stopped when we banned such testing.
leeoniya 14y ago
one thing i never understood about fusion is how you can capture all the released energy efficiently enough. isn't it released in many ways that cannot really be harnessed directly eg: gamma radiation, x-rays, emf. that makes me think that the input:output ratio would need to be not just marginally better, but sufficiently better. does anyone know what the current best input:captured number is?
- InclinedPlane 14y ago
  Almost all of the energy comes out as kinetic energy of the fusion byproducts, which are mainly atomic nuclei and neutrons. Sadly, a great deal of the energy of the easiest to achieve fusion reactions (D-D and D-T) tends to exist in the neutrons released by the reactions. And those neutrons tend to fly right out of the charged plasma quite readily. This makes creating a self-sustaining magnetically confined fusion reaction more difficult but it also makes building a fusion reactor slightly challenging. But far from impossible. Neutrons can penetrate fairly deeply through many materials but fortunately ordinary water serves as a robust shield. So by surrounding a fusion reaction with water you can quite easily capture most of the energy of the fusion reactions and can use an ordinary steam turbine generator to produce electricity.
- snarfy 14y ago
  It depends on the type of fuel used. The holy grail is a boron + hydrogen reaction, which produces three helium nuclei. Since the nuclei are positively charged and moving quickly, the net voltage is around 2 million volts. When done correctly, fusion will create electricity directly. At that point it's just a matter of stepping it down to a usable voltage, but we have lots of ways to do that.
- gryphonic 14y ago
  Usually you are trying to catch neutrons in a lithium blanket, and using the fission products to extract energy. At least that is what they are doing at ITER. The electromagnetic energy goes back into the plasma and helps with keeping things hot. The energy extraction is one of the biggest challenges with sustained fusion.
- uvdiv 14y ago
politician 14y ago
Misleading title, from the article NIF is a weapons research project.
breckenedge 14y ago
I'm all for fusion research. Love the idea of clean, inexhaustible power. However, the NIF has consistently over promised and under delivered, and they have no idea _what_ their problems are [1]. They could use a little restraint when making schedule predictions. [1] http://fire.pppl.gov/NIF_NIC_report_rev5_koonin_2012.pdf http://fire.pppl.gov/NIF_NIC_report_rev5_koonin_2012.pdf
- cjensen 14y ago
  Yep. NIF is such an old project that it was used as the "digitizer" in the original TRON movie. Still no progress.
  - shardling 14y ago
    What a silly thing to say -- of course there has been progress, even if it's only a better understanding of what doesn't work.
    - cjensen 14y ago
      Only the US bothers with lasers because everyone else understands that lasers don't work for fusion. Tokamaks are where it's at. The only real use of NIF is to better understand fusion so as to better understand how nuclear weapons work. I just want them to be honest about it.
      - uvdiv 14y ago
        Only the US bothers with lasers because everyone else understands that lasers don't work for fusion. https://en.wikipedia.org/wiki/Laser_Mégajoule https://en.wikipedia.org/wiki/Laser_Mégajoule I personally think lasers are much more promising, if only because of how much room there is for disruption with solid-state lasers. Look at how horrible the NIF lasers are: ~1% efficient [0], billions of dollars, the size of a warehouse [1]. And the fusion end seems to work fine. [0] https://lasers.llnl.gov/about/nif/about.php https://lasers.llnl.gov/about/nif/about.php [1] https://en.wikipedia.org/wiki/National_Ignition_Facility#Driver_laser https://en.wikipedia.org/wiki/National_Ignition_Facility#Dri...

30 points by ananyob 14y ago

eggoa 14y ago

Relevant graph: http://commons.wikimedia.org/wiki/File:U.S._historical_fusion_budget_vs._1976_ERDA_plan.png http://commons.wikimedia.org/wiki/File:U.S._historical_fusio...

Flenser 14y ago
Here's the paper the graph refers to. The original graph is on page 12: http://fire.pppl.gov/us_fusion_plan_1976.pdf http://fire.pppl.gov/us_fusion_plan_1976.pdf
simba-hiiipower 14y ago
wow, that’s pretty sad. the 'moderate' path would have required an average expenditure of ~$2.5 billion a year, and projected the completion of a reactor by 2005. a pretty small investment when you consider the size of the federal budget [1] and where most of the funding goes. even more sad, when considering the likelihood that many graphs relating to other potentially transformative technologies probably look much the same.. [1] http://en.wikipedia.org/wiki/Expenditures_in_the_United_States_federal_budget http://en.wikipedia.org/wiki/Expenditures_in_the_United_Stat...
- jerf 14y ago
  Uh... I would not take that graph as some sort of gospel. The truth is that even now we do not have an effective known path to economically viable fusion power generation, and if nothing else our computer simulations are indescribably better than anything they had in the late 70s. Had we blown billions more in the 80s, we probably would simply have blown billions more in the 80s and still have no fusion today.
  - simba-hiiipower 14y ago
    that may be true, but getting it (or any new technology for that matter) to the point where it’d be economically viable requires an investment at some point.. and ‘blowing’ those billions in the 80s may very-well not have paid-off with economically viable fusion power today, but i highly doubt it would have left us with nothing to show for it.
    - jerf 14y ago
      We don't really have a hell of a lot to show for what we have spent. Non-zero, sure, but a lot of the lessons we learned could certainly have been learned for a lot more cheaply if we hadn't tried to leap to the end of the process with grandiose projects built more on hope than science.
- throwit1979 14y ago
  $2.5B is roughly on par with the combined 2012 salaries of all NFL teams( $90MM - $118MM per team, at the cap ). Which is as it should be, since football is far more important to humanity than something as silly as cheap, safe, and clean energy.
danielweber 14y ago
One thing I take from this graph is that doubling fusion funding would still leave us at "fusion never", so we shouldn't bother doubling it. :(

ck2 14y ago

to help weapons scientists to care for the ageing US nuclear stockpile Simulating explosions helps determine maintenance for nuclear warheads? I would bet they were more likely trying to make a "nuclear" weapon without radiation/fallout and failed. I wonder what the world would be like with really cheap power though - I'd like to think a better place to live but more likely there would be a lot more war since the energy to do it would then be cheap.

mchouza 14y ago
Simulating explosions helps determine maintenance for nuclear warheads? It's not completely unreasonable: they need to validate the computational models that are used to check if an aged nuclear weapon will explode.
kd5bjo 14y ago
Second order effects can be quite surprising: as gasoline replaced whale oil as a fuel source, it also increased the demand for cars. This accelerated the practice of whaling because whale oil remained extremely desirable as the lubricant inside transmissions.
Someone 14y ago
One of the things with maintenance is that, although you do not want to use your them, you must make sure that your warheads work if you ever need them. The traditional and easiest way of doing that is to frequently build new warheads, and test explode the older ones. That is expensive and, nowadays, forbidden/frowned upon (I think the test ban treaty hasn't been ratified) So, one stops building new ones and ends up with thirty+ year old warheads. The radioactive materials inside them have aged, steel may have become brittle, etc. To ascertain whether these devices still work, tests are needed. You could do them on the devices themselves, but it is easier and cheaper to do an experiment with a few grams of radioactive materials than to work with a kg or so from a warhead (all IIRC; corrections welcome)
ChuckMcM 14y ago
"Simulating explosions helps determine maintenance for nuclear warheads?" Yes. Radioactive material is, by definition, slowly becoming non-radioactive by decaying into other atoms. You can think of those other atoms as 'contaminants' in your plutonium soup. What this means is if you create a nuclear warhead, and put it on the shelf, if you did nothing you would have a very sophisticated box holding some lead. But long before that it stops working as a nuclear warhead. So what you do is you take put one on the shelf in the lab and you sample it periodically to see how its content has changed, and run your simulations to see if plutonium or uranium with those makeups would still work within the boundaries of the device, and you try to test it periodically under conditions that simulate, as much as possible, an actual explosion. They used to do this at the test site, basically explode one warhead from a batch every 2 - 3 years to insure they still worked. But they stopped when we banned such testing.

leeoniya 14y ago

one thing i never understood about fusion is how you can capture all the released energy efficiently enough. isn't it released in many ways that cannot really be harnessed directly eg: gamma radiation, x-rays, emf. that makes me think that the input:output ratio would need to be not just marginally better, but sufficiently better. does anyone know what the current best input:captured number is?

InclinedPlane 14y ago
Almost all of the energy comes out as kinetic energy of the fusion byproducts, which are mainly atomic nuclei and neutrons. Sadly, a great deal of the energy of the easiest to achieve fusion reactions (D-D and D-T) tends to exist in the neutrons released by the reactions. And those neutrons tend to fly right out of the charged plasma quite readily. This makes creating a self-sustaining magnetically confined fusion reaction more difficult but it also makes building a fusion reactor slightly challenging. But far from impossible. Neutrons can penetrate fairly deeply through many materials but fortunately ordinary water serves as a robust shield. So by surrounding a fusion reaction with water you can quite easily capture most of the energy of the fusion reactions and can use an ordinary steam turbine generator to produce electricity.
snarfy 14y ago
It depends on the type of fuel used. The holy grail is a boron + hydrogen reaction, which produces three helium nuclei. Since the nuclei are positively charged and moving quickly, the net voltage is around 2 million volts. When done correctly, fusion will create electricity directly. At that point it's just a matter of stepping it down to a usable voltage, but we have lots of ways to do that.
gryphonic 14y ago
Usually you are trying to catch neutrons in a lithium blanket, and using the fission products to extract energy. At least that is what they are doing at ITER. The electromagnetic energy goes back into the plasma and helps with keeping things hot. The energy extraction is one of the biggest challenges with sustained fusion.
uvdiv 14y ago

politician 14y ago

Misleading title, from the article NIF is a weapons research project.

breckenedge 14y ago

I'm all for fusion research. Love the idea of clean, inexhaustible power. However, the NIF has consistently over promised and under delivered, and they have no idea _what_ their problems are [1]. They could use a little restraint when making schedule predictions. [1] http://fire.pppl.gov/NIF_NIC_report_rev5_koonin_2012.pdf http://fire.pppl.gov/NIF_NIC_report_rev5_koonin_2012.pdf

cjensen 14y ago
Yep. NIF is such an old project that it was used as the "digitizer" in the original TRON movie. Still no progress.
- shardling 14y ago
  What a silly thing to say -- of course there has been progress, even if it's only a better understanding of what doesn't work.
  - cjensen 14y ago
    Only the US bothers with lasers because everyone else understands that lasers don't work for fusion. Tokamaks are where it's at. The only real use of NIF is to better understand fusion so as to better understand how nuclear weapons work. I just want them to be honest about it.
    - uvdiv 14y ago
      Only the US bothers with lasers because everyone else understands that lasers don't work for fusion. https://en.wikipedia.org/wiki/Laser_Mégajoule https://en.wikipedia.org/wiki/Laser_Mégajoule I personally think lasers are much more promising, if only because of how much room there is for disruption with solid-state lasers. Look at how horrible the NIF lasers are: ~1% efficient [0], billions of dollars, the size of a warehouse [1]. And the fusion end seems to work fine. [0] https://lasers.llnl.gov/about/nif/about.php https://lasers.llnl.gov/about/nif/about.php [1] https://en.wikipedia.org/wiki/National_Ignition_Facility#Driver_laser https://en.wikipedia.org/wiki/National_Ignition_Facility#Dri...