13 ms·

The article mentions losses at the hohlraum but doesn't mention losses in the laser. "Ignition" means they controled the implosion well enough to break (almost)

The article mentions losses at the hohlraum but doesn't mention losses in the laser. "Ignition" means they controled the implosion well enough to break (almost) even on laser energy, but the laser itself is less than 1% efficient on wall power. Input energy to the entire system is over 400 MJ per shot. Even at max theoretical fusion yield, it wouldn't come close to breakeven. There's also a firing rate issue. Even if the system produced net power, significant production would require many shots per second. Currently, the laser flash lamps are expendable and it takes on the order of a day (and lots of money) to prep for each shot. Some of these drawbacks were addressed in the LIFE proposal, which would use fusion neutrons to burn fission fuel in a blanket around the fusion chamber. You could burn spent reactor fuel subcritically (no fission chain reaction), for example. But then it's a fission machine, and criticality excursions aren't much of an issue in conventional fission reactors. In the end, there are many drawbacks and little benefit with such a setup -- even if it worked. I love lasers, and NIF is a marvel. But there really is no sensical story about power production in it. Even the machine's stated purpose -- stockpile maintenence -- is highly dubious. It is really an elaborate welfare machine, given to weapons scientists in exchange for their support of testing bans.

leephillips 5y ago
I think your take on this is accurate, but it’s a little deeper than a welfare program. The government needs to maintain a population of cleared scientists who know how to calculate things like fusion yields, simulated with classified codes. These fake fusion energy programs contribute to that; some of the most capable scientists don’t want to work on weapons, so they can kid themselves that they are working on “energy”. There is no reasonably foreseeable future with fusion as part of the electricity grid. Even if we got fantastically lucky and were able to build a practical (magnetic or inertial) reactor in 50 years, by that time improvements in energy storage and transmission technologies will have allowed renewable energy to dominate, and no government would be crazy enough to permit it to be built. http://progressive.org/op-eds/let-cut-our-losses-on-fusion-energy-180313/ http://progressive.org/op-eds/let-cut-our-losses-on-fusion-e...
- eloff 5y ago
  > no government would be crazy enough to permit it to be built Why? Nuclear fusion doesn't have the meltdown risk or waste problems of fission.
  - leephillips 5y ago
    There is no meltdown risk with modern fission reactor designs. But there is the waste problem. If you follow the links my Op-Ed, you’ll find articles describing the radioactive waste and proliferation risks that will accompany any fusion reactor. Not as great as fission, but far from zero. And there is the problem of production and transportation of tritium, a very nasty substance. A commercial fusion reactor would be fantastically expensive and complex, and require a huge infrastructure to support it.
    - blablabla123 5y ago
      "Does Fusion produce radioactive nuclear waste the same way fission does? Nuclear fission power plants have the disadvantage of generating unstable nuclei; some of these are radioactive for millions of years. Fusion on the other hand does not create any long-lived radioactive nuclear waste. Can fusion reactors be used to produce weapons? No." https://www.iaea.org/topics/energy/fusion/faqs https://www.iaea.org/topics/energy/fusion/faqs
      - leephillips 5y ago
        Right, as other commenters have pointed out, this is low-level radioactive waste. It, along with tritium, is great for dirty bombs and catnip to terrorists. A dirty bomb is a weapon. They are talking about “atom bombs”.
        kortilla 5y ago
        > is great for dirty bombs and catnip to terrorists. This is another variant of “think of the children”. How many terrorists have built these dirty bombs?
sam0x17 5y ago
Having toured NIF a few times and worked in one of the buildings adjacent to it a few summers ago, I will say the energy stuff always seemed more like a way to get funding. The main use and aim for NIF is and always has been to re-create some of the conditions inside nuclear weapons and similar fusion-based reactions. The whole NIF building has the ability to switch modes between classified and unclassified. They wouldn't have gone through the trouble of making this a toggleable feature on the building if they weren't actively using it for both.
- sleavey 5y ago
  > The whole NIF building has the ability to switch modes between classified and unclassified. Interesting, can you explain this more? What gets hidden?
  - sam0x17 5y ago
    I don't know the specifics but I imagine most of it is waving a magic wand and saying poof now this room is classified. But there are logistics that go with that, certain door technologies that have to be in place, probably some complex security procedure for "switching" between modes, (i.e. I would think they need to clear the building of uncleared personnel and be 100% sure there isn't someone hiding in a bathroom somewhere) etc etc, and it's enough of a pain that most buildings are either one or the other all the time. The ability to switch on the fly for a large facility like that is super rare and indicative of there being a real need for switching. All I know for sure is on the tour they mention they can switch the whole building to be unclassified or classified and during the tour it is in unclassified mode.
    - maxerickson 5y ago
      I imagine a big chunk of switching to classified is shooing the un-cleared visitors.
      - sam0x17 5y ago
        Likewise for going from classified mode to unclassified mode they would have to sweep the whole facility for sensitive material
phkahler 5y ago
>> There's also a firing rate issue. Even if the system produced net power, significant production would require many shots per second. Currently, the laser flash lamps are expendable and it takes on the order of a day (and lots of money) to prep for each shot. Oh, but then there's this part: >> Further experiments will require the manufacture of additional fuel capsules and hohlraums. These may not be ready until at least October, Herrmann says. The nanocrystalline diamond-coated capsule that was imploded in this month’s event took six months to grow at General Atomics, which has long worked with LLNL on fabricating capsules. The spheres have to be polished and the core’s interior etched with tools inserted through a 2-micron-diameter hole drilled into it. The tritium–deuterium mixture is injected through a tiny fill tube just prior to the shot.
- hutzlibu 5y ago
  Well, it is aweseom tech. But probably nothing I would bet we can rely on, soon.
- val314159 5y ago
  for the love of god, someone please rename these "diluthium crystals"!
- feoren 5y ago
  That's actually uplifting to read! Even if we don't end up getting fusion power out of this, it's got to be helping fund improvements in nano-manufacturing!
MurMan 5y ago
> There's also a firing rate issue ... The NIF goal was ignition, not continuous power production. The original spec was one shot every four hours. Achieving one shot per day is close.
dukoid 5y ago
My money is on stellarators. Just saw Wendelstein in the newsfeed here: https://news.ycombinator.com/item?id=28211413 https://news.ycombinator.com/item?id=28211413
- pfdietz 5y ago
  Stellarators face many of the same likely showstoppers as tokamaks. Power density, materials, maintainability, complexity, cost.
pfdietz 5y ago
> the LIFE proposal, which would use fusion neutrons to burn fission fuel in a blanket around the fusion chamber. This is crazy. If you are going to have fission and fission products, you might as well just build a fission reactor. It would be vastly simpler, smaller, and cheaper. http://web.mit.edu/fusion-fission/WorkshopTalks/skepticsvg.pdf http://web.mit.edu/fusion-fission/WorkshopTalks/skepticsvg.p...
w-ll 5y ago
In the utmost respect, you sound like Lazlo from the movie Real Geniuses. https://www.youtube.com/watch?v=HoT-h0S1gkE https://www.youtube.com/watch?v=HoT-h0S1gkE
noobermin 5y ago
The nuclear stockpile bit is kind of true, although it's sort of true, HEDP systems are the only way in a controlled setting to create nuclear level conditions without setting off a nuke. That said, NIF at least from the energy perspective just like ITER was just to push the research forward than it was to produce break-even fusion in 10 years. If you really want that you'll need gobs of money, probably even beyond the level of things like the LHC. The reason we don't have fusion in either field (MCF or ICF) is because we don't fund it to that level. EDIT: on funding, this[0] image shows what is neccessary and the level we actually funded. It's been around for a while but it may prove informative for the uninitiated. [0]https://i.imgur.com/3vYLQmm.png https://i.imgur.com/3vYLQmm.png
- seventytwo 5y ago
  I get the point the graph’s authors are making, but I wonder how those projections (made in the 70s) would hold up today, knowing what we know about the engineering challenges for each fusion approach. In other words, I’d love to see a 2021 recreation of that graph.

leephillips 5y ago

I think your take on this is accurate, but it’s a little deeper than a welfare program. The government needs to maintain a population of cleared scientists who know how to calculate things like fusion yields, simulated with classified codes. These fake fusion energy programs contribute to that; some of the most capable scientists don’t want to work on weapons, so they can kid themselves that they are working on “energy”. There is no reasonably foreseeable future with fusion as part of the electricity grid. Even if we got fantastically lucky and were able to build a practical (magnetic or inertial) reactor in 50 years, by that time improvements in energy storage and transmission technologies will have allowed renewable energy to dominate, and no government would be crazy enough to permit it to be built. http://progressive.org/op-eds/let-cut-our-losses-on-fusion-energy-180313/ http://progressive.org/op-eds/let-cut-our-losses-on-fusion-e...

eloff 5y ago
> no government would be crazy enough to permit it to be built Why? Nuclear fusion doesn't have the meltdown risk or waste problems of fission.
- leephillips 5y ago
  There is no meltdown risk with modern fission reactor designs. But there is the waste problem. If you follow the links my Op-Ed, you’ll find articles describing the radioactive waste and proliferation risks that will accompany any fusion reactor. Not as great as fission, but far from zero. And there is the problem of production and transportation of tritium, a very nasty substance. A commercial fusion reactor would be fantastically expensive and complex, and require a huge infrastructure to support it.
  - blablabla123 5y ago
    "Does Fusion produce radioactive nuclear waste the same way fission does? Nuclear fission power plants have the disadvantage of generating unstable nuclei; some of these are radioactive for millions of years. Fusion on the other hand does not create any long-lived radioactive nuclear waste. Can fusion reactors be used to produce weapons? No." https://www.iaea.org/topics/energy/fusion/faqs https://www.iaea.org/topics/energy/fusion/faqs
    - leephillips 5y ago
      Right, as other commenters have pointed out, this is low-level radioactive waste. It, along with tritium, is great for dirty bombs and catnip to terrorists. A dirty bomb is a weapon. They are talking about “atom bombs”.
      - kortilla 5y ago
        > is great for dirty bombs and catnip to terrorists. This is another variant of “think of the children”. How many terrorists have built these dirty bombs?

sam0x17 5y ago

Having toured NIF a few times and worked in one of the buildings adjacent to it a few summers ago, I will say the energy stuff always seemed more like a way to get funding. The main use and aim for NIF is and always has been to re-create some of the conditions inside nuclear weapons and similar fusion-based reactions. The whole NIF building has the ability to switch modes between classified and unclassified. They wouldn't have gone through the trouble of making this a toggleable feature on the building if they weren't actively using it for both.

sleavey 5y ago
> The whole NIF building has the ability to switch modes between classified and unclassified. Interesting, can you explain this more? What gets hidden?
- sam0x17 5y ago
  I don't know the specifics but I imagine most of it is waving a magic wand and saying poof now this room is classified. But there are logistics that go with that, certain door technologies that have to be in place, probably some complex security procedure for "switching" between modes, (i.e. I would think they need to clear the building of uncleared personnel and be 100% sure there isn't someone hiding in a bathroom somewhere) etc etc, and it's enough of a pain that most buildings are either one or the other all the time. The ability to switch on the fly for a large facility like that is super rare and indicative of there being a real need for switching. All I know for sure is on the tour they mention they can switch the whole building to be unclassified or classified and during the tour it is in unclassified mode.
  - maxerickson 5y ago
    I imagine a big chunk of switching to classified is shooing the un-cleared visitors.
    - sam0x17 5y ago
      Likewise for going from classified mode to unclassified mode they would have to sweep the whole facility for sensitive material

phkahler 5y ago

>> There's also a firing rate issue. Even if the system produced net power, significant production would require many shots per second. Currently, the laser flash lamps are expendable and it takes on the order of a day (and lots of money) to prep for each shot. Oh, but then there's this part: >> Further experiments will require the manufacture of additional fuel capsules and hohlraums. These may not be ready until at least October, Herrmann says. The nanocrystalline diamond-coated capsule that was imploded in this month’s event took six months to grow at General Atomics, which has long worked with LLNL on fabricating capsules. The spheres have to be polished and the core’s interior etched with tools inserted through a 2-micron-diameter hole drilled into it. The tritium–deuterium mixture is injected through a tiny fill tube just prior to the shot.

hutzlibu 5y ago
Well, it is aweseom tech. But probably nothing I would bet we can rely on, soon.
val314159 5y ago
for the love of god, someone please rename these "diluthium crystals"!
feoren 5y ago
That's actually uplifting to read! Even if we don't end up getting fusion power out of this, it's got to be helping fund improvements in nano-manufacturing!

MurMan 5y ago

> There's also a firing rate issue ... The NIF goal was ignition, not continuous power production. The original spec was one shot every four hours. Achieving one shot per day is close.

dukoid 5y ago

My money is on stellarators. Just saw Wendelstein in the newsfeed here: https://news.ycombinator.com/item?id=28211413 https://news.ycombinator.com/item?id=28211413

pfdietz 5y ago
Stellarators face many of the same likely showstoppers as tokamaks. Power density, materials, maintainability, complexity, cost.

pfdietz 5y ago

> the LIFE proposal, which would use fusion neutrons to burn fission fuel in a blanket around the fusion chamber. This is crazy. If you are going to have fission and fission products, you might as well just build a fission reactor. It would be vastly simpler, smaller, and cheaper. http://web.mit.edu/fusion-fission/WorkshopTalks/skepticsvg.pdf http://web.mit.edu/fusion-fission/WorkshopTalks/skepticsvg.p...

w-ll 5y ago

In the utmost respect, you sound like Lazlo from the movie Real Geniuses. https://www.youtube.com/watch?v=HoT-h0S1gkE https://www.youtube.com/watch?v=HoT-h0S1gkE

noobermin 5y ago

The nuclear stockpile bit is kind of true, although it's sort of true, HEDP systems are the only way in a controlled setting to create nuclear level conditions without setting off a nuke. That said, NIF at least from the energy perspective just like ITER was just to push the research forward than it was to produce break-even fusion in 10 years. If you really want that you'll need gobs of money, probably even beyond the level of things like the LHC. The reason we don't have fusion in either field (MCF or ICF) is because we don't fund it to that level. EDIT: on funding, this[0] image shows what is neccessary and the level we actually funded. It's been around for a while but it may prove informative for the uninitiated. [0]https://i.imgur.com/3vYLQmm.png https://i.imgur.com/3vYLQmm.png

seventytwo 5y ago
I get the point the graph’s authors are making, but I wonder how those projections (made in the 70s) would hold up today, knowing what we know about the engineering challenges for each fusion approach. In other words, I’d love to see a 2021 recreation of that graph.