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Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

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Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#131

Post by psychlops »

raverbashing wrote: post #113
randallsquared wrote: post #103

Earlier quoted context omitted.

> 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.

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

> My crazy idea would be to use the heat and the pressure of these to pump water uphill.

This is a great idea, not crazy.

It ignores the steampunk future that awaits us all!

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#132

Post by graycat »

garyclarke27 wrote: post #9

Most interesting fact from the article. At the system level it took 300 million Joules to produce 3 Million a 1% return - so still a very long way to go! With this kind of approach I can’t see how fusion can ever be cheap, the capital costs are enormous. Better to focus on standardised production lines for small fission reactors.

Hmm .... Mars has nearly no atmosphere, and, thus, nearly no bad weather, clouds, fog, rain, etc. That is, it's sunshine all the time!

Sooo, for Mars, just put the solar panels near the equator and fairly densely all around the circumference. Then, wow, have solar power 100% of the time!

Do the same on Earth??? Ah, have some jungles, mountains, two major oceans, and a lot of bad weather. For the oceans, sure, have floating solar arrays. Right, need to think about how deep the power cables to the shore would be, 3-7 miles down and then back up?

But the Internet has some cables across oceans!! Sooo, we could also have power cables???

Ah, sounds like only for Mars!

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#133

Post by HPsquared »

dotancohen wrote: post #108
HPsquared wrote: post #97

Earlier quoted context omitted.

Parent was basically saying it has not been a physics problem for decades, it's already an engineering problem and there is no change there. The physics are known to work and have been demonstrated decades ago in a different engineering context (i.e. weapons).

As I understand it - correct me if I'm wrong - one of the consequences of the December 5 experiment is that the engineering uncertainty was brought into the realm of "this now fits the progress of engineering, so we expect to be able to engineer the thing given sufficient capital and time", rather than the previous "we have no idea if we'll ever be able to engineer this thing".

It has always been a matter of building a machine with sufficient performance. That's engineering, by definition.

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#134

Post by wongarsu »

rob74 wrote: post #43

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 ), you are using a nuclear fission primary stage to generate enough energy to start the fusion reaction in the secondary stage. In the NIF,…

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_propuls...

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#135

Post by HPsquared »

zmgsabst wrote: post #114
HPsquared wrote: post #97

Earlier quoted context omitted.

Parent was basically saying it has not been a physics problem for decades, it's already an engineering problem and there is no change there. The physics are known to work and have been demonstrated decades ago in a different engineering context (i.e. weapons).

We can debate the importance, but it’s clear that they’ve made a qualitative leap in their technology the past few years — a “breakthrough”. https://en.wikipedia.org/wiki/National_Ignition_Facility#/me...

That's quite the leap, clearly some big progress when it's presented like that.

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#136

Post by acidburnNSA »

tonmoy wrote: post #115

This type of nuclear fusion uses tritium, and since we can’t extract it from nature the only way to obtain it is very energy extensive. For this type of fusion to make sense producing tritium+lasers have to require less energy than the output, right?

The power plant version of this produces enough tritium as it captures the heat in a breeding blanket of lithium outside the core.

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#137

Post by torpfactory »

Being able to do “ignition” reliably means you can do experiments in a regime where the energy from fusion starts to become a large part of the reaction. Dynamics in this regime are non-linear, so being able to actually test there is fairly important. Updating models and simulation inputs based on these results should make some further progress possible. This device is significantly different than a power reactor, but other efforts might see a benefit from a better understanding of reaction physics during “ignition”.

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#138

Post by HPsquared »

sudhirj wrote: post #65

It’s practical proof that in a single pulse we can get more energy out than we put in. We do spend a shit ton of energy setting up the pulse, and we haven’t figure out how to get that energy out and make electrons move, but it’s been proven possible. The “breakthrough” is the proof that it’s possible. Everything else is now optimisation and engineering, and needs mostly time, sweat and money.

That was already proven in weapons tests in the 1950s (e.g. https://en.m.wikipedia.org/wiki/Castle_Bravo). The hard part is always building the machine to produce net energy gain, which is still 2+ orders of magnitude away.

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#139

Post by tadfisher »

headsoup wrote: post #96
sigmoid10 wrote: post #86

Earlier quoted context omitted.

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, bu…

But isn't the 'net positive', itself only a factor in the very last stage of all of the input energy required for ignition? So they need to factor in all other components before looking at these orders of magnitude being useful?

Yes, but that is still a breakthrough.

Re: Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

#140

Post by manholio »

dotancohen wrote: post #108
HPsquared wrote: post #97

Earlier quoted context omitted.

Parent was basically saying it has not been a physics problem for decades, it's already an engineering problem and there is no change there. The physics are known to work and have been demonstrated decades ago in a different engineering context (i.e. weapons).

As I understand it - correct me if I'm wrong - one of the consequences of the December 5 experiment is that the engineering uncertainty was brought into the realm of "this now fits the progress of engineering, so we expect to be able to engineer the thing given sufficient capital and time", rather than the previous "we have no idea if we'll ever be able to engineer this thing".

> rather than the previous "we have no idea if we'll ever be able to engineer this thing".

We still have no idea if we'll ever be able to engineer this thing to produce commercially useful energy. And we probably never will, for all interesting values of "never", the challenges are simply so massive.

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