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Still unconvinced why this is such a major breakthrough - it may be the first net-positive controlled fusion, but the distinction between controlled and uncontr

by rob74 4y ago

Still unconvinced why this is such a major breakthrough - it may be the first net-positive controlled fusion, but the distinction between controlled and uncontrolled fusion is a bit academic in this case. In uncontrolled fusion (https://en.wikipedia.org/wiki/Thermonuclear_weapon https://en.wikipedia.org/wiki/Thermonuclear_weapon), you are using a nuclear fission primary stage to generate enough energy to start the fusion reaction in the secondary stage. In the NIF, you are using lasers (that have to be aligned to trillionths of a meter and damage their own guiding optics everytime they fire) to start the fusion reaction in a smaller pellet (that costs hundreds of thousands of dollars). So the only real difference between the first and the second case is that the H-bomb is smaller, much more expensive per amount of energy released, and explodes inside a chamber. And it's obvious to pretty much everyone who is paying attention that transforming this setup into a working and cost-effective fusion power plant is a very tall order. Also, what somehow always gets left out of these articles is that the NIF is a military facility financed from the "(Nuclear) Stockpile Stewardship" budget. So its primary objective is studying fusion in a controlled way, but for building better bombs (and retaining the expertise necessary to build them), not for energy production.

Systemic33 4y ago
With regards to NIF being a military facility, I'd very much think that energy production (cheap, safe, limitless?) is very much a military needs as much as a civilian need. Even if said energy goes further to power laser weapons or other exotic power hungry systems; energy is energy, and something has to produce it.
- oblio 4y ago
  The internet was a military need from what I remember. The military said something like: "Telephone routing is point to point and inflexible, if the enemy cuts out 1-2 lines of communication, an entire section is completely cut off. We need something better." That something better turned out to be packed switching where you just throw stuff along a network and the network ensures that the packet reaches the destination, but you could theoretically have two packets going from Bucharest to Johannesburg, one through India and the second one through Canada.
  - noobermin 4y ago
    That said while the intent the current internet is pretty centralized at least in some senses.
    - DecoPerson 4y ago
      But it’s software defined, so it’s much quicker to work around failures of those centralised points.
      - est31 4y ago
        Yeah compare broken water pipes with broken facebook/whatsapp etc. If the former is broken, people don't have water until the issue is fixed. With latter, at least they can use one of the alternatives (and they do, usage counts of alternatives go up during outages).
        noobermin 4y ago
        Yeah, I'm not talking about broken facebook or twitter, I'm talking about the various cdns out there, cloudfare, etc
        oblio 4y ago
        Even for those. Swapping a CDN or infra provider is difficult, but hardly impossible. It's much easier than the same operation for physical infrastructure.
        HPsquared 4y ago
        That is, unless the water pipes require internet to work.
  - thereddaikon 4y ago
    It started as a way to network air defense bases for AESA radars, NORAD and Nike missiles together across CONUS. Feature creep and increased scope grew it into a general purpose data network that linked not only military sites but also research institutes by the 80's.
- rob74 4y ago
  Depends - if someday they manage to make the fusion generators compact enough (think of the coffee-machine-sized "Mr. Fusion" that Dr. Brown brought back from 2015 in Back to the Future where you could throw in any kind of junk and it would use it to provide energy, or even the shipping container-sized units that Lockheed Martin is envisaging), it might be interesting for military purposes. But it's very optimistic to believe that the NIF will seriously work on sustained fusion and extracting the generated energy in a usable way - after all they are called National Ignition Facility, so now they achieved that, mission accomplished. They can now run further ignition experiments with various pellets, laser configurations etc. and study the results, but they will probably say that a new facility (and more money) is needed for further studying sustained fusion.
- mikeyouse 4y ago
  NIF being a "military facility" has less to do with laser weapons or power-hungry systems than their type of research indirect drive laser-fusion, being the exact mechanism that takes place in multiple-stage nuclear weapons. The lasers at NIF first generate x-rays, which are then focused on the target to energize the pellet and create fusion. If you look at the "shot history" of NIF -- the vast majority of their facility's energy is spent on actual DOD weapons research, not fusion power research that would be incidentally beneficial to the DOD: https://lasers.llnl.gov/for-users/nif-target-shot-metrics https://lasers.llnl.gov/for-users/nif-target-shot-metrics
sigmoid10 4y ago
You greatly underestimate the order of magnitude difference of produced energy in these two examples. You can't contain a bomb's hydrogen fusion reaction in a chamber for the simple reason that you need a nuclear fission warhead just to ignite it. So if you want to produce useful, controlled energy outside of killing things, the lasers are your only shot for inertial confinement fusion. Yes they still get damaged, but lasers have seen ridiculous advancements in precision and instantaneous power over the past few decades. This news shows that practical fusion is now only an engineering problem, not a fundamental physics one - like it still is for Tokamaks and Stellarotors. For them noone knows if it is even possible to e.g. control turbulence long enough to achieve net positive energy gain.
- randallsquared 4y ago
  > You can't contain a bomb's hydrogen fusion reaction in a chamber You certainly can, if you use a large enough chamber. Pacer was exactly this. You just have to accept high proliferation risk.
  - raverbashing 4y ago
    True. My crazy idea would be to use the heat and the pressure of these to pump water uphill. It is of course a crazy idea and you'd have to figure out a way to manage the pressure peak But it would be very interesting
    - mikepurvis 4y ago
      Pumped hydro has been a concept for a while now for grid storage of power; one of the limitations of it is just the rather unique geography required. Most places with adjacent reservoirs and enough vertical separation between them also have cottages, roads, and other infra that make it hard to be constantly draining and filling.
      - GuB-42 4y ago
        It is not just a concept, it represent the vast majority of grid energy storage today, we are talking about gigawatts. Hydro is the best, so good in fact that most of the good spots are already taken, because as you said, it requires a very specific geography.
jacquesm 4y ago
And that's before we get into the total system efficiency issues.
wongarsu 4y ago
If we can get unit-costs on those pellets down, that sounds like a great starting point for high-speed spacecraft propulsion. Not in the Expanse "pellets explode and produce electricity" way but in the Project Orion "explode nuclear bombs behind a shock absorber and ride the shockwave" way [1]. Just that this allows you to build much smaller and more manageable spacecraft (important since you probably still want to reach orbit with more traditional propulsion) 1: https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...
throwawaymaths 4y ago
It's not even close to net positive. It's more energy out than the lasers put in. But the lasers take in WAAAAY more than they put in.
- felipellrocha 4y ago
  What are you talking about? They put in 2MJs of energy in, and got back 3.5MJs out?
  - russdill 4y ago
    They lasers are about 1% efficient. The actual energy required is hundreds of MJ.
  - throwawaymaths 4y ago
    If your "they" refers to the lasers, the lasers put in 2mj, correct. That is not what "they" (my they) put in to the lasers.
whywhywhydude 4y ago
“So the only real difference between the first and the second case is that the H-bomb is smaller, much more expensive per amount of energy released, and explodes inside a chamber” - that sounds like a major technological breakthrough to me. They managed to concentrate so much energy inside a chamber in a controlled manner.
woeirua 4y ago
This comment sums up HN beautifully: "Here's an article from a subject matter expert on this topic, but I'm going to go ahead and ignore everything that was said because it doesn't fit my narrative."
- Sohcahtoa82 4y ago
  I mean, that's the entire internet.
- hinkley 4y ago
  You find us a subject matter expert in building production fusion power plants and we’ll get back to you. What we have are a bunch of R&D people, some of which are using ingredients for which the entire world combined possesses enough fuel to run a single power plant for only two months, and then we’re out.
  - hinkley 4y ago
    Too late to edit, but my source on the 2 months comment comes from an interview with Helion, who I think made the front page a couple of weeks ago, but in summary they are trying to smash two plasma balls together and then directly capture the magnetic flux created by the resulting fusion, rather than using a heat engine: https://youtube.com/watch?v=_bDXXWQxK38&t=1081s https://youtube.com/watch?v=_bDXXWQxK38&t=1081s They talk about why ITER has no viable fuel source, and about how they (Helion) are going to have to run two configurations of fusion plants in order to source their own fuel. One that produces a 10% power surplus, undesirable neutrons and the fuel for their power plants. They didn’t say anything but I suspect they’ll end up coming up with a use for the neutrons, perhaps making fuels for other processes. Someone will likely eyeball that waste heat as well.
WhitneyLand 4y ago
Major breakthrough is a subjective term so it’s hard to argue that precisely, but is it a major milestone on the way to commercial fusion, or “historic” as Dr. Kuranz says in the article? I can accept that. In 50 years, I’d guess it’ll be described in Wikipedia in such as way. Secondly I’m not sure what you mean by saying this experiment has only academic differences with a thermonuclear weapon. It seems the only similarity is they both generate a fusion reaction. The latter is essentially multiple bombs strapped together which is quite different practically.

by rob74 4y ago

Systemic33 4y ago

With regards to NIF being a military facility, I'd very much think that energy production (cheap, safe, limitless?) is very much a military needs as much as a civilian need. Even if said energy goes further to power laser weapons or other exotic power hungry systems; energy is energy, and something has to produce it.

oblio 4y ago
The internet was a military need from what I remember. The military said something like: "Telephone routing is point to point and inflexible, if the enemy cuts out 1-2 lines of communication, an entire section is completely cut off. We need something better." That something better turned out to be packed switching where you just throw stuff along a network and the network ensures that the packet reaches the destination, but you could theoretically have two packets going from Bucharest to Johannesburg, one through India and the second one through Canada.
- noobermin 4y ago
  That said while the intent the current internet is pretty centralized at least in some senses.
  - DecoPerson 4y ago
    But it’s software defined, so it’s much quicker to work around failures of those centralised points.
    - est31 4y ago
      Yeah compare broken water pipes with broken facebook/whatsapp etc. If the former is broken, people don't have water until the issue is fixed. With latter, at least they can use one of the alternatives (and they do, usage counts of alternatives go up during outages).
      - noobermin 4y ago
        Yeah, I'm not talking about broken facebook or twitter, I'm talking about the various cdns out there, cloudfare, etc
        oblio 4y ago
        Even for those. Swapping a CDN or infra provider is difficult, but hardly impossible. It's much easier than the same operation for physical infrastructure.
      - HPsquared 4y ago
        That is, unless the water pipes require internet to work.
- thereddaikon 4y ago
  It started as a way to network air defense bases for AESA radars, NORAD and Nike missiles together across CONUS. Feature creep and increased scope grew it into a general purpose data network that linked not only military sites but also research institutes by the 80's.
rob74 4y ago
Depends - if someday they manage to make the fusion generators compact enough (think of the coffee-machine-sized "Mr. Fusion" that Dr. Brown brought back from 2015 in Back to the Future where you could throw in any kind of junk and it would use it to provide energy, or even the shipping container-sized units that Lockheed Martin is envisaging), it might be interesting for military purposes. But it's very optimistic to believe that the NIF will seriously work on sustained fusion and extracting the generated energy in a usable way - after all they are called National Ignition Facility, so now they achieved that, mission accomplished. They can now run further ignition experiments with various pellets, laser configurations etc. and study the results, but they will probably say that a new facility (and more money) is needed for further studying sustained fusion.
mikeyouse 4y ago
NIF being a "military facility" has less to do with laser weapons or power-hungry systems than their type of research indirect drive laser-fusion, being the exact mechanism that takes place in multiple-stage nuclear weapons. The lasers at NIF first generate x-rays, which are then focused on the target to energize the pellet and create fusion. If you look at the "shot history" of NIF -- the vast majority of their facility's energy is spent on actual DOD weapons research, not fusion power research that would be incidentally beneficial to the DOD: https://lasers.llnl.gov/for-users/nif-target-shot-metrics https://lasers.llnl.gov/for-users/nif-target-shot-metrics

sigmoid10 4y ago

You greatly underestimate the order of magnitude difference of produced energy in these two examples. You can't contain a bomb's hydrogen fusion reaction in a chamber for the simple reason that you need a nuclear fission warhead just to ignite it. So if you want to produce useful, controlled energy outside of killing things, the lasers are your only shot for inertial confinement fusion. Yes they still get damaged, but lasers have seen ridiculous advancements in precision and instantaneous power over the past few decades. This news shows that practical fusion is now only an engineering problem, not a fundamental physics one - like it still is for Tokamaks and Stellarotors. For them noone knows if it is even possible to e.g. control turbulence long enough to achieve net positive energy gain.

randallsquared 4y ago
> You can't contain a bomb's hydrogen fusion reaction in a chamber You certainly can, if you use a large enough chamber. Pacer was exactly this. You just have to accept high proliferation risk.
- raverbashing 4y ago
  True. My crazy idea would be to use the heat and the pressure of these to pump water uphill. It is of course a crazy idea and you'd have to figure out a way to manage the pressure peak But it would be very interesting
  - mikepurvis 4y ago
    Pumped hydro has been a concept for a while now for grid storage of power; one of the limitations of it is just the rather unique geography required. Most places with adjacent reservoirs and enough vertical separation between them also have cottages, roads, and other infra that make it hard to be constantly draining and filling.
    - GuB-42 4y ago
      It is not just a concept, it represent the vast majority of grid energy storage today, we are talking about gigawatts. Hydro is the best, so good in fact that most of the good spots are already taken, because as you said, it requires a very specific geography.

jacquesm 4y ago

And that's before we get into the total system efficiency issues.

wongarsu 4y ago

If we can get unit-costs on those pellets down, that sounds like a great starting point for high-speed spacecraft propulsion. Not in the Expanse "pellets explode and produce electricity" way but in the Project Orion "explode nuclear bombs behind a shock absorber and ride the shockwave" way [1]. Just that this allows you to build much smaller and more manageable spacecraft (important since you probably still want to reach orbit with more traditional propulsion) 1: https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...

throwawaymaths 4y ago

It's not even close to net positive. It's more energy out than the lasers put in. But the lasers take in WAAAAY more than they put in.

felipellrocha 4y ago
What are you talking about? They put in 2MJs of energy in, and got back 3.5MJs out?
- russdill 4y ago
  They lasers are about 1% efficient. The actual energy required is hundreds of MJ.
- throwawaymaths 4y ago
  If your "they" refers to the lasers, the lasers put in 2mj, correct. That is not what "they" (my they) put in to the lasers.

whywhywhydude 4y ago

“So the only real difference between the first and the second case is that the H-bomb is smaller, much more expensive per amount of energy released, and explodes inside a chamber” - that sounds like a major technological breakthrough to me. They managed to concentrate so much energy inside a chamber in a controlled manner.

woeirua 4y ago

This comment sums up HN beautifully: "Here's an article from a subject matter expert on this topic, but I'm going to go ahead and ignore everything that was said because it doesn't fit my narrative."

Sohcahtoa82 4y ago
I mean, that's the entire internet.
hinkley 4y ago
You find us a subject matter expert in building production fusion power plants and we’ll get back to you. What we have are a bunch of R&D people, some of which are using ingredients for which the entire world combined possesses enough fuel to run a single power plant for only two months, and then we’re out.
- hinkley 4y ago
  Too late to edit, but my source on the 2 months comment comes from an interview with Helion, who I think made the front page a couple of weeks ago, but in summary they are trying to smash two plasma balls together and then directly capture the magnetic flux created by the resulting fusion, rather than using a heat engine: https://youtube.com/watch?v=_bDXXWQxK38&t=1081s https://youtube.com/watch?v=_bDXXWQxK38&t=1081s They talk about why ITER has no viable fuel source, and about how they (Helion) are going to have to run two configurations of fusion plants in order to source their own fuel. One that produces a 10% power surplus, undesirable neutrons and the fuel for their power plants. They didn’t say anything but I suspect they’ll end up coming up with a use for the neutrons, perhaps making fuels for other processes. Someone will likely eyeball that waste heat as well.

WhitneyLand 4y ago

Major breakthrough is a subjective term so it’s hard to argue that precisely, but is it a major milestone on the way to commercial fusion, or “historic” as Dr. Kuranz says in the article? I can accept that. In 50 years, I’d guess it’ll be described in Wikipedia in such as way. Secondly I’m not sure what you mean by saying this experiment has only academic differences with a thermonuclear weapon. It seems the only similarity is they both generate a fusion reaction. The latter is essentially multiple bombs strapped together which is quite different practically.