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US Department of Energy: Fusion Ignition Achieved

energy.gov

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Re: US Department of Energy: Fusion Ignition Achieved

#461

Post by garfieldnate »

bmmayer1 wrote: post #103
jkelleyrtp wrote: post #33

> LLNL’s experiment surpassed the fusion threshold by delivering 2.05 megajoules (MJ) of energy to the target, resulting in 3.15 MJ of fusion energy output, demonstrating for the first time a most fundamental science basis for inertial fusion energy (IFE) Yesterday, everyone was complaining about the 2.2:2.0 ratio, but now we're working with 3.15:2.05. With modern lasers, that'd be a total Q of 0.375 assuming 100% ef…

This is a stupid question but I don't know anything about fusion: How is it possible for X energy to create X+Y energy in output? Doesn't that violate some fundamental law of physics?

I think it's more like a release of potential energy; kind of like how you can lightly nudge a large object teetering on the edge of a cliff and it'll make a huge splash at the bottom. It took a lot of energy to create the big splash, but you didn't need much to trigger it.

Re: US Department of Energy: Fusion Ignition Achieved

#462

Post by lostmsu »

readams wrote: post #65
psychoslave wrote: post #43

Is that a different approach than the Tokamak, some piece to make it works, or some other relationship? What does it mean for existing projects such as ITER? https://en.wikipedia.org/wiki/Tokamak https://en.wikipedia.org/wiki/ITER

This works in a totally different way, by heating a tiny target fuel pellet with a laser to cause it to collapse and trigger fusion through basically heating and squeezing: more like how a bomb works. It's not easy to see a direct path from this approach to a power plant, but it might involve lining up a steady stream of fuel targets and doing this in a sort of pulsed mode. Other approaches attempt to create a contin…

In principle inertial confinement is not much different from internal combustion engines where piston compresses the mix, and the explosion energy is harvested. Here lasers compress the mix, and the explosion energy is not yet harvested (but measured).

Tokamaks (the other approach) are more like jet engines in that they sustain burning. But currently the burning in tokamaks requires more energy than it generates.

Re: US Department of Energy: Fusion Ignition Achieved

#463

Post by sweezyjeezy »

whimsicalism wrote: post #395
petilon wrote: post #349

Earlier quoted context omitted.

When you consider that they laser they used consumed 300 megajoules from the wall plug, in order to send 1.8 megajoules to the target, the fact that they got 2.5 megajoules out looks puny in comparison. Even newer lasers only have 20% wall plug efficiency according to the press conference. So the important point here is, there was no net energy gain. They spent 300 megajoules to get 2.5 out. The scientists only talk…

Energy is conserved in the universe so there is never any net energy gain. See how pedantic and not helpful that is?

Power plants add energy to an electrical grid by converting external (chemical/nuclear/kinetic) energy into more electricity than they consume. There's no loss of energy/mass overall, but the amount of available electricity goes up. Since the laser would use electricity from the grid, that should be taken into account.

Re: US Department of Energy: Fusion Ignition Achieved

#464

Post by davrosthedalek »

saboot wrote: post #413
davrosthedalek wrote: post #407

Earlier quoted context omitted.

Not really. I mean, yes, nuclear weapons are a thing, but Dept. of Energy supports many many directions not related to nuclear weapons. Physics research is mostly funded by DOE Office of Science or the National Science Foundation.

It's an explicit goal of the NIF to better understand the physics of fusion for weapons research. Not the main one but it's pretty important!

My point was: NIF would be funded via DOE whether or not it's relevant for weapon research. Sorry for not have been clearer.

Re: US Department of Energy: Fusion Ignition Achieved

#465

Post by Retric »

dgacmu wrote: post #221
spullara wrote: post #113

Earlier quoted context omitted.

I mean almost all of the power in a nuclear bomb comes from fusion. The fission part of it is just like the detonator for the real explosion.

This is actually backwards. Fusion weapons are substantially higher yield because they result in more fission, partly by preventing the fission primary from blowing itself up before it has finished. Wikipedia: "Fast fission of the tamper and radiation case is the main contribution to the total yield and is the dominant process that produces radioactive fission product fallout." https://en.m.wikipedia.org/wiki/Thermon…

It varies quite a bit by design, apparently the USSR’s initial design was only 15-20% fusion while US designs where closer to 50% which is still apparently the most efficient option in terms of warhead size.

However it’s possible to have higher fusion ratios at the expense of a larger device for the same yield. Most notably in the case of the Tsar Bomba’s which reduced the contribution of fission and too massively reduce the amount of fallout produced.

Re: US Department of Energy: Fusion Ignition Achieved

#466

Post by ars »

yonaguska wrote: post #445
subsubzero wrote: post #372

Earlier quoted context omitted.

Do we know how much tritium is needed for a city's energy generation? What about a state etc? Reason I ask is the only uses I have seen for tritium is on old watch dials made in the pre-90's. Curious how much of this resource is out there.

Tritium is very popular on gun sights as well- as it's a glow in the dark sight that doesn't need to be charged. I'm now questioning the practice of appendix carrying with tritium sights.

Tritium decays by beta-decay (an electron). The electron can not travel very far in air (1/4 inch), and is stopped by even the thinnest piece of metal. It's even stopped by the dead outer layer of your skin.

i.e. it's completely harmless unless you eat it.

Re: US Department of Energy: Fusion Ignition Achieved

#467

Post by VLM »

pfdietz wrote: post #71
jkelleyrtp wrote: post #33

> LLNL’s experiment surpassed the fusion threshold by delivering 2.05 megajoules (MJ) of energy to the target, resulting in 3.15 MJ of fusion energy output, demonstrating for the first time a most fundamental science basis for inertial fusion energy (IFE) Yesterday, everyone was complaining about the 2.2:2.0 ratio, but now we're working with 3.15:2.05. With modern lasers, that'd be a total Q of 0.375 assuming 100% ef…

The Q needs to be something like 500 to 1000, not because of energy breakeven, but to produce enough energy that the shot is financially positive. The amount of fusion energy produced in this shot is worth a penny or two. (And even then, it's dubious a laser fusion scheme will be competitive with other energy sources.)

Its worth pointing out that per unit energy a lot of money is made making economically unviable cargo ship power, submarine and other military naval power, space ship power sources, diesel-electric locomotives ...

True if you want to replace base load of a civilization size network it needs to be economically viable, but we generate "a lot" of power at higher than market minima. Ironically, "good batteries" are the natural enemy of fusion research.

One fun thing about laser fusion is it theoretically can scale down very low and has a trivial "off" switch making it a good resource for engineering tokamak reactor materials or sensors or similar tasks.

The inner lining of a production fusion reactor is hard to make, so a laser facility would be ideal for research. Which is why we have one...

Re: US Department of Energy: Fusion Ignition Achieved

#468

Post by lostmsu »

wnevets wrote: post #234
aetherson wrote: post #173

Earlier quoted context omitted.

It's not like the "wormhole" thing where what was produced isn't really what can plausibly be described as a wormhole. In this case, fusion really did happen, and the amount of energy produced by the fusion reaction was about half again what the energy put into the fusion reaction was. That said, there are two pretty important caveats about how big a deal it is macroscopically: 1. In order to have useful fusion power…

> 2. This is from an inertial confinement approach to fusion. Unlike the magnetic confinement approaches that we often hear about, this approach doesn't really create a continuously hot, spatially constrained bit of plasma that can then be used to heat things up -- it produces more like a small but intense explosion. There are real doubts about whether you can, even with very favorable energy-out ratios, industrializ…

> Thank you, that is the kind of caveat I was expecting.

The caveat on caveat is that historically explosions (piston internal combustion engines) were developed before continuous burning (jet turbines).

Re: US Department of Energy: Fusion Ignition Achieved

#469

Post by josho »

anon291 wrote: post #208
brofallon wrote: post #30

I'm still a little unclear on the benefits that fusion offers compared to things like wind and solar. I understand that we need to develop better storage technologies for the energy produced by wind and solar, but that seems so much easier than the challenges currently facing fusion. Wind and solar just seem so far ahead of fusion already - they're pretty cheap and very widely deployed on a global scale. In compariso…

Solar and wind have massive environmental impacts. Fusion's foot print is much smaller for the same output. Batteries are rather dangerous. Fusion is -- as far as I understand it -- much less likely to escape a reactor due to how difficult it is to sustain the reaction. Moreover, it's more dependable. So in sum, the advantages are (1) dependability, (2) safety, and (3) small footprint.

> Solar and wind have massive environmental impacts

Got a source for this? The only time I've seen this has been political talking points that had no backing.

Re: US Department of Energy: Fusion Ignition Achieved

#470

Post by rmbyrro »

bmmayer1 wrote: post #103
jkelleyrtp wrote: post #33

> LLNL’s experiment surpassed the fusion threshold by delivering 2.05 megajoules (MJ) of energy to the target, resulting in 3.15 MJ of fusion energy output, demonstrating for the first time a most fundamental science basis for inertial fusion energy (IFE) Yesterday, everyone was complaining about the 2.2:2.0 ratio, but now we're working with 3.15:2.05. With modern lasers, that'd be a total Q of 0.375 assuming 100% ef…

This is a stupid question but I don't know anything about fusion: How is it possible for X energy to create X+Y energy in output? Doesn't that violate some fundamental law of physics?

Nothing is being actually "created", just converted.
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