5 ms·

I don't get it. Wouldn't that mean it required 302.05MJ to get 3.15MJ?

teach 4y ago
Yes. In nuclear fusion, "ignition" means that you get more energy out than the lasers impart. This is the first time anyone has pulled that off in decades of trying, which is a big deal. But practical nuclear fusion would of course require that you get out more energy _from the entire system_ than you put in, and getting there will require even more problems to be solved. But now at least one obstacle has been overcome!
- JumpCrisscross 4y ago
  > "ignition" means that you get more energy out than the lasers impart. This is the first time anyone has pulled that off in decades of trying, which is a big deal. The term is refreshingly intuitive. For decades we've been striking stone and flint. Sparks. We just got a bit of kindling going. It's no bonfire. But it's a big step forward.
- WithinReason 4y ago
  >This is the first time anyone has pulled that off in decades of trying, which is a big deal. Are you sure of that? This is from 2014: https://arstechnica.com/science/2014/02/giant-leap-for-nuclear-fusion-as-scientists-get-more-energy-out-than-fuel-put-in/?itm_source=parsely-api https://arstechnica.com/science/2014/02/giant-leap-for-nucle...
  - falcor84 4y ago
    Quoting from the article you linked to: Hurricane’s current output, although more than the hydrogen fuel put into the reaction, hasn’t yet reached the stated goal to achieve “ignition," where nuclear fusion generates as much energy as the lasers supply. At that point it might be possible to make a sustainable power plant based on the technology.
  - tingletech 4y ago
    from your article: > Hurricane’s current output, although more than the hydrogen fuel put into the reaction, hasn’t yet reached the stated goal to achieve “ignition," where nuclear fusion generates as much energy as the lasers supply.
- darksaints 4y ago
  How do fusion bombs achieve "ignition"? It's not with lasers, right? Also, couldn't the net energy from the ignition be used to continue the reaction, so you only need the lasers for startup? Sorry for the newb questions, just curious.
  - scarier 4y ago
    With a fission bomb. Don’t have a good explanation for your second question, although I think the short answer is “not with the way the Livermore experiment was set up.”
  - jboy55 4y ago
    Caveat: This comment is derived from publicly available info. An H-bomb is a two part bomb. The primary bomb is a implosion plutonium bomb similar in make to the nagasaki/trinity bomb. It is theorized the Xrays from that bomb are focused on a secondary cylinder of uranium-238 that has a core of hydrogen and/or lithium. The Xrays ablate this casing at such intensity that the inward force (the opposite force of the ablation) is strong enough to propell the casing inwards at 300 km/second. This squeezes the hydrogen/lithium and causes fusion which releases a tone of energy, but more importantly a huge amount of neutrons. These neutrons cause the 238 in the casing to fission releasing an even greater amount of energy. A Neutron bomb for example replaces some/all of the 238 with lead, so the neutrons escape without causing more fision. Again, this is all speculation from scientists outside the various labs, and using publicly available information. For power generation, since the energy from any fusion reaction is primarily emitted as heat and neutrons. The neutrons are difficult to utilize and is basically wasted energy, but the heat would just heat water, turning it into steam, then turning a turbine.
OkayPhysicist 4y ago
The purpose of NIF is to investigate the practicality of inertial confinement, not "be a production fusion reactor". They don't use bleeding edge laser tech, nor are they really built to generate significant amounts of power. For context, modern lasers are ~20x more efficient than the ones that NIF is using. Reporting based on the energy put into the reaction itself (the lasers) reflects far better the feasibility of the confinement tech than spending an inordinate amount of budget on an already incomprehensibly expensive science experiment to try and optimize every last edge condition.
- lordnacho 4y ago
  Aha that makes sense, it's a jumpstart basically?
  - ep103 4y ago
    proof of concept, yeah.
- jboy55 4y ago
  The purpose of NIF is primarily to study the effects of age on our nuclear weapons stockpile by simulating the x-ray blast of the primary nuclear device on the secondary fusion stage within an h-bomb in a controlled environment. Then we can tell how the hydrogen stage will be affected by age, and probably how we can optimize the contents and casing of that to be smaller and last longer. Any benefits to the future of power generation is a secondary goal.
mikeyouse 4y ago
Kind of.. It's like saying you used a 1% efficient 100HP pump to start a water wheel that eventually was outputting 1.5HP of power. We know how to make more efficient pumps, so it's not terribly interesting that it took 100HP of power to generate the 1.5HP -- the fact that only 1HP of output power was actually used to start the 1.5HP reaction is the big deal.
giblfiz 4y ago
Yes, but the name "ignition" is very useful. The idea, ultimately, is that like with a wood fire, the energy from the fuel "burning" is what starts the next bit of fuel "burning", and then as it runs on it's own as long as you keep giving it more fuel, you collect the excess heat by boiling water. So, similar to a wood fire, you might need to use a blowtorch to get it started, and run at a net negative of energy, but the exciting thing is that there was a little flame... that means we can probably make a roaring fire out of it.
- TheOtherHobbes 4y ago
  No it doesn't. If you throw some fuel in their general direction, oxygen fires are self-sustaining with relatively little effort. It takes more effort to stop a large oxygen fire than to make one. Fusion is the opposite. Fusion's natural state is Not Fusing, so in ICF you have to keep compressing and heating the fuel. Using equipment with optically tight tolerances and epic pulsed energy densities. Which are somehow maintained reliably for long periods. In spite of significant debris and huge temperature swings.
  - kortex 4y ago
    Fire's natural state is burning only at standard temperature and pressure (or greater). If you look at the "average" state of all space in the universe, fire is not stable.

Yes. In nuclear fusion, "ignition" means that you get more energy out than the lasers impart. This is the first time anyone has pulled that off in decades of trying, which is a big deal. But practical nuclear fusion would of course require that you get out more energy _from the entire system_ than you put in, and getting there will require even more problems to be solved. But now at least one obstacle has been overcome!

JumpCrisscross 4y ago
> "ignition" means that you get more energy out than the lasers impart. This is the first time anyone has pulled that off in decades of trying, which is a big deal. The term is refreshingly intuitive. For decades we've been striking stone and flint. Sparks. We just got a bit of kindling going. It's no bonfire. But it's a big step forward.
WithinReason 4y ago
>This is the first time anyone has pulled that off in decades of trying, which is a big deal. Are you sure of that? This is from 2014: https://arstechnica.com/science/2014/02/giant-leap-for-nuclear-fusion-as-scientists-get-more-energy-out-than-fuel-put-in/?itm_source=parsely-api https://arstechnica.com/science/2014/02/giant-leap-for-nucle...
- falcor84 4y ago
  Quoting from the article you linked to: Hurricane’s current output, although more than the hydrogen fuel put into the reaction, hasn’t yet reached the stated goal to achieve “ignition," where nuclear fusion generates as much energy as the lasers supply. At that point it might be possible to make a sustainable power plant based on the technology.
- tingletech 4y ago
  from your article: > Hurricane’s current output, although more than the hydrogen fuel put into the reaction, hasn’t yet reached the stated goal to achieve “ignition," where nuclear fusion generates as much energy as the lasers supply.
darksaints 4y ago
How do fusion bombs achieve "ignition"? It's not with lasers, right? Also, couldn't the net energy from the ignition be used to continue the reaction, so you only need the lasers for startup? Sorry for the newb questions, just curious.
- scarier 4y ago
  With a fission bomb. Don’t have a good explanation for your second question, although I think the short answer is “not with the way the Livermore experiment was set up.”
- jboy55 4y ago
  Caveat: This comment is derived from publicly available info. An H-bomb is a two part bomb. The primary bomb is a implosion plutonium bomb similar in make to the nagasaki/trinity bomb. It is theorized the Xrays from that bomb are focused on a secondary cylinder of uranium-238 that has a core of hydrogen and/or lithium. The Xrays ablate this casing at such intensity that the inward force (the opposite force of the ablation) is strong enough to propell the casing inwards at 300 km/second. This squeezes the hydrogen/lithium and causes fusion which releases a tone of energy, but more importantly a huge amount of neutrons. These neutrons cause the 238 in the casing to fission releasing an even greater amount of energy. A Neutron bomb for example replaces some/all of the 238 with lead, so the neutrons escape without causing more fision. Again, this is all speculation from scientists outside the various labs, and using publicly available information. For power generation, since the energy from any fusion reaction is primarily emitted as heat and neutrons. The neutrons are difficult to utilize and is basically wasted energy, but the heat would just heat water, turning it into steam, then turning a turbine.

OkayPhysicist 4y ago

The purpose of NIF is to investigate the practicality of inertial confinement, not "be a production fusion reactor". They don't use bleeding edge laser tech, nor are they really built to generate significant amounts of power. For context, modern lasers are ~20x more efficient than the ones that NIF is using. Reporting based on the energy put into the reaction itself (the lasers) reflects far better the feasibility of the confinement tech than spending an inordinate amount of budget on an already incomprehensibly expensive science experiment to try and optimize every last edge condition.

lordnacho 4y ago
Aha that makes sense, it's a jumpstart basically?
- ep103 4y ago
  proof of concept, yeah.
jboy55 4y ago
The purpose of NIF is primarily to study the effects of age on our nuclear weapons stockpile by simulating the x-ray blast of the primary nuclear device on the secondary fusion stage within an h-bomb in a controlled environment. Then we can tell how the hydrogen stage will be affected by age, and probably how we can optimize the contents and casing of that to be smaller and last longer. Any benefits to the future of power generation is a secondary goal.

mikeyouse 4y ago

Kind of.. It's like saying you used a 1% efficient 100HP pump to start a water wheel that eventually was outputting 1.5HP of power. We know how to make more efficient pumps, so it's not terribly interesting that it took 100HP of power to generate the 1.5HP -- the fact that only 1HP of output power was actually used to start the 1.5HP reaction is the big deal.

giblfiz 4y ago

Yes, but the name "ignition" is very useful. The idea, ultimately, is that like with a wood fire, the energy from the fuel "burning" is what starts the next bit of fuel "burning", and then as it runs on it's own as long as you keep giving it more fuel, you collect the excess heat by boiling water. So, similar to a wood fire, you might need to use a blowtorch to get it started, and run at a net negative of energy, but the exciting thing is that there was a little flame... that means we can probably make a roaring fire out of it.

TheOtherHobbes 4y ago
No it doesn't. If you throw some fuel in their general direction, oxygen fires are self-sustaining with relatively little effort. It takes more effort to stop a large oxygen fire than to make one. Fusion is the opposite. Fusion's natural state is Not Fusing, so in ICF you have to keep compressing and heating the fuel. Using equipment with optically tight tolerances and epic pulsed energy densities. Which are somehow maintained reliably for long periods. In spite of significant debris and huge temperature swings.
- kortex 4y ago
  Fire's natural state is burning only at standard temperature and pressure (or greater). If you look at the "average" state of all space in the universe, fire is not stable.