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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

#921

Post by PaulHoule »

eru wrote: post #832
aoetalks wrote: post #810

Earlier quoted context omitted.

This is incredible.

To give some more detail: hydrogen to helium fusion (even with intermediate steps) is extremely unlikely to happen. That's part of why the sun will last for billions of years. And that's also why first human attempts at fusion are not trying to use straight up hydrogen as the fuel. Good old Wikipedia has this gem: > The large power output of the Sun is mainly due to the huge size and density of its core (compared to…

Those Fusors can make a decent neutron source however. Those were invented by Philo Farnsworth, who invented the cathode ray tube for television.

Re: US Department of Energy: Fusion Ignition Achieved

#922

Post by Balgair »

Mistletoe wrote: post #778
Balgair wrote: post #574

Earlier quoted context omitted.

I agree. This is a Big deal. Like, first-lightbulb big, or polio-vaccine big. My kids are likely to spend the majority of their lives living a world where energy is clean, cheap, and available to everyone. Climate change is something that is not only going to be stopped, but can be reversed for them. Energy grids can be made to be smaller and mutually supporting, lessening the impacts of disasters. Oil dependency and…

This is such a profound and deep misunderstanding of this news story.

how so?

Re: US Department of Energy: Fusion Ignition Achieved

#923

Post by teilo »

w0mbat wrote: post #577
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…

Their total power draw from the grid was 300 megajoules and they got back about 3 megajoules, so don't start celebrating yet. Source: New York Times.

Now add in the 50% efficiency of conversion of heat to electricity (and that's very optimistic), and it's only 1.5 megajoules, or 0.5%, right where I calculated it based on initial information.

IANAP, but I see no path forward to sufficient Q-total using plasma fusion to put this to any practical use. Unless the reaction can somehow be self-sustaining, I do not believe this will ever work.

Re: US Department of Energy: Fusion Ignition Achieved

#924

Post by kennend3 »

moloch-hai wrote: post #792
eropple wrote: post #620

Earlier quoted context omitted.

As I understand it, iron is the first element that absorbs energy under fusion, and therefore won't fuse further. Could be wrong, though.

It will happily fuse further. It just won't support the outside of a star against gravity, while doing it. So the star collapses, fuses lots more stuff even heavier than iron, and then explodes. Most of the iron and heavier stuff fuses into the core of a neutron star, the ultimate in energy-consuming fusion.

None of this is accurate.

Iron will not happily fuse further because this NEEDS energy and where would that energy come from?

"heavier than iron" elements are produced when a star explodes because that collapse produces enormous amounts of energy.

During the collapse, the outer edge of the star is accelerated to something like 20% of the speed of light, that is an ENORMOUS amount of energy slamming down on the core.

Lastly, neutron starts don't produce energy, they are the incompressible remnants of a dead star.

Re: US Department of Energy: Fusion Ignition Achieved

#925

Post by hyperbovine »

w0mbat wrote: post #577
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…

Their total power draw from the grid was 300 megajoules and they got back about 3 megajoules, so don't start celebrating yet. Source: New York Times.

Explains why the experiment took place at 1am.

Re: US Department of Energy: Fusion Ignition Achieved

#926

Post by PaulHoule »

Apocryphon wrote: post #849
snshn wrote: post #94

I like how over 60 years after the nuclear boom, it somehow just happened to happen today. Just when the world is ready to transition to electric vehicles on a global scale, just when oil companies aren't able to make as much money from oil as they used to, just when one of the major suppliers of fossil fuels (Russia) is at war with the West, it has somehow magically happened. What a coinky-dink. Throw lots of money…

Is that you, Lyndon?

Lyndon Larouche came to my high school (in New Hampshire) for the presidential primaries in 1988 and talked about antimatter as an energy source.

Years later I saw a picture of an Iranian woman holding a sign that said "Nuclear Power is a Human Right" and thought... She much be a LaRouchite.

I wound up voting for Diane Sare, another LaRouchite, for US Senate in New York this year even though I know they're a coercive organization like the Scientologists or the Longtermists and I disagreed with her position on Ukraine -- we had a really sad ballot this year since they made it much harder for 3rd party candidates to get one and she was the only one.

LaRouchites are the only people left who want to stamp out the Beatles but they are required to not only listen to only classical music but are only allowed to listen to Brahms and anything older. If I ran into a LaRouchite and wanted to make them squirm I would talk to them about Debussy.

Re: US Department of Energy: Fusion Ignition Achieved

#927

Post by tgflynn »

lambdatronics wrote: post #854
tgflynn wrote: post #111

Earlier quoted context omitted.

I wonder if it might be possible to gain not percentages but orders of magnitude more or less just by making the targets bigger. Is it conceivable that the same basic approach and a comparable amount of input energy could be used to ignite a 100 MJ or even 1 GJ target ? Of course that would present some containment challenges but perhaps not insurmountable ones. I'm also a bit concerned that this type of research may…

The bigger the target, the more energy is needed to compress it. So it would require more laser energy to get to 100 MJ or 1 GJ, I think. But maybe only a few times more powerful. (Pity they didn't build in some head room!)

The question is whether once ignition is achieved there could be a way to design the target/geometry in such a way that the fusion reaction becomes self-sustaining/self-propagating.

The history of thermonuclear weapons leads me to think that the answer may be yes. There does not seem to be any real upper limit to how large a thermonuclear weapon can be made. In the 50's and/or 60's there were proposals to build GT devices. I don't think the fission trigger for such a weapon could have scaled by nearly as much.

So by analogy if a relatively small fission trigger can cause a fusion explosion that is many orders of magnitudes larger maybe one or more tiny laser induced fusion reactions could be used to trigger a much larger one.

If that were the case the efficiency of the laser trigger would be of little importance.

Re: US Department of Energy: Fusion Ignition Achieved

#928

Post by doctorwho42 »

hackbinary wrote: post #679
w0mbat wrote: post #577

Earlier quoted context omitted.

Their total power draw from the grid was 300 megajoules and they got back about 3 megajoules, so don't start celebrating yet. Source: New York Times.

300 MJ is about 83 KWh. In the UK is 1 KWh is £0.34 So, this costs £28 in electricity to run this experiment. The experiment is a momentary thing. Clearly there is now some work to, but now this is becoming an engineering problem of how to extend, sustain, and scale this process.

Having worked in the field for 6 years, the estimated cost per shot at NIF is roughly $1MM. The estimated cost for a day of shots at OMEGA is $250k-$300k.

The cost per target varies a lot due to the precise manufacturing tolerances and the methods to get them. For example, the sphere with the fuel in it is made by dropping liquid glass from a drop tower. And then metrology is done on hundreds and hundreds of glass spheres.

So though the electricity might cost that, we are talking about a building in which just the lasers and their optical paths take up 3 foot ball fields of advanced warehouse space. And the target chamber is at ultra high vacuum, which is 10 meters in diameter. There are also countless diagnostics, computers, and other electronics, the lights for all the facility, and the number of people required to run it so this delicate experiment goes off without a hitch.

Honestly, it's almost not worth talking about as a power source anytime soon. Even if Q > 2 on NIF there are countless engineering problems that would have to be overcome (and haven't really been thought too hard on in the ICF field) to get a power reactor out of this tech.

My two cents, look towards MIT and CFS for news on their SPARC tokamak and plans for ARC tokamak. Based on some data I have seen, SPARC should hit Q>1 pretty easily. With some estimates of reaching Q> 3 to 9. And before you scoff at it, this reactor design is using magnetic tech that has proven it can withstand and produce a 20T magnetic field! In MCF, field strength and heating are the two key metrics. To put this into perspective, the massive tokamak being built in Europe has a MAX possible field strength of 13T, assuming it's run to the edge of it's theoretical design limitations. The SPARC one hasn't even been run to it's design limitations, most likely due to the mechanical stresses a 20T field produces in a 3-4 meter D coil.

Re: US Department of Energy: Fusion Ignition Achieved

#929

Post by epgui »

eru wrote: post #793
floxy wrote: post #686

Earlier quoted context omitted.

I guess we should take this as a lesson in communications. The "breakeven" thing is a red-herring that should have been have been left out of the message, or at least only mentioned as a footnote. The critical ELI5 message that should have been presented is that they used a laser to create some tiny amount of fusion. But we have been able to do that for a while now. The important thing is that they were then able to…

> [...], or the ginormous fusion of the sun. The sun actually has very little fusion per cubic metre or per kg. Per volume the core of the sun produces only a quarter of the heat of the human body (and per kg it's even less, owing to high density). That's why our fusion reactors can't just mimic stars, they have to far surpass them to be useful to us.

The per-volume claim rings alarms in my head.

If it produced a quarter of the heat of the human body per volume, its temperature would be lower as well (less than 37 degrees Celsius).[1] This is obviously not the case.

[1] Obviously heat and temperature are not the same, I know that. But when something’s temperature is higher than another thing’s, then heat is exchanged along that gradient. Meaning if the sun produced less volumetric heat than the human body, a human body placed within the sun would warm the sun and cool the human.

Re: US Department of Energy: Fusion Ignition Achieved

#930

Post by PaulHoule »

twarge wrote: post #375
kahrl wrote: post #241

Earlier quoted context omitted.

https://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect

I have a PhD plasma physics, I think I am qualified to make these statements without this sort of dismissal!

It sucks doesn't it!

I met a physicist who had written a paper in the 1980s about a fusion reactor that used the high energy neutrons from D-T fusion to breed ²³³U from ²³²Th, around the time that people were losing interest in fast reactors. The reactor itself might not be a profitable source of energy directly, but the fuel it produces would be useful in thermal fission reactors.

Fusion will be attractive as a neutron source long before it is attractive as an energy source, in fact there are many kinds of neutron generators already in use that use fusion.

The waste from fusion will be different in character from fission. Unless you are trying to make TRU you are not going to have any transuranic waste. Most of the real danger from fission products is in isotopes of a few elements in a particular range of atomic number, particular Cs and I.

On the other hand, a D-T reactor is going to have a lot of T around and T is hard to contain since hydrogen likes to infiltrate between the atoms in metals. The flux of neutrons on the first wall is going to be absolutely brutal, how bad the activation is will depend on what exact materials you're using, but the difficulty of the situation is such that you might not have much of a choice.

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