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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

#91

Post by danbruc »

TheOtherHobbes wrote: post #76
danbruc wrote: post #59

Earlier quoted context omitted.

For one, it's theoretically impossible to make lasers 102 times more efficient, especially if you consider the current industrial efficiency of up to 20% (30% under special conditions). That is not true. You can of course not make a 10 % efficient laser more than 10 times more efficient, but there is no limit to how much more efficient you can make a laser in general, you just have to start with an inefficient enough…

I'm not sure if it's theoretically impossible. But it's certainly an incredible challenge to build a high efficiency laser system that can consistently generate many pulses per second without degrading either the laser head itself or any associated micro-focussing optics. Can we stop pretending this isn't about nuclear weapons research and - basically - continued funding? LLNL is at least a decade behind its initial…

My point was purely about the claimed impossibility of a hundredfold efficiency increase which is only true if you are already about 1 % efficient. I have no real opinion on what the NIF is doing or not, at best my layman judgment would be that laser fusion is way further from becoming practical than tokamaks or stellerators.

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

#92

Post by noobermin »

est31 wrote: post #87
DecoPerson wrote: post #67

Earlier quoted context omitted.

But it’s software defined, so it’s much quicker to work around failures of those centralised points.

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).

Yeah, I'm not talking about broken facebook or twitter, I'm talking about the various cdns out there, cloudfare, etc

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

#93

Post by Whitespace »

I find it interesting that people talk in absolutes ("fusion will never be economical!") when the devices they're using were "impossible" only a few decades ago.

Also the difference between a 4:00:00 marathon and a 3:59:59 is less than a 0.007% improvement but it's a huge victory nonetheless. Once someone proves an arbitrary numerical barrier can be overcome humans tend to make a lot of progress shortly thereafter.

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

#94

Post by tpmx »

vesinisa wrote: post #58
bawolff wrote: post #39

Everything i have heard about this makes it sound more like a milestone than a breakthrough. I.e. its great it happened and an important step, but its not shocking that we eventually did it. When i hear breakthrough i think of something more unexpected. I.e. figuring out how to solve a problem we had no idea how to solve.

Exactly.. The article fails to answer the question posed by its very title. What I've gathered, this was a very much expected result and NOT a "breakthrough". And with regards to making fusion a viable source for commercial, large-scale energy production .. this is only tangential at best to that effort. The problem with celebrating "fake victories" (and being scolded for calling them out) is that when there really i…

Another danger:

I've seen quite a few people arguing in (a European context) that we shouldn't build out nuclear in the "short term", "since we can just get fusion without any of the downsides of fission".

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

#95

Post by jokteur »

tpmx wrote: post #94
vesinisa wrote: post #58

Earlier quoted context omitted.

Exactly.. The article fails to answer the question posed by its very title. What I've gathered, this was a very much expected result and NOT a "breakthrough". And with regards to making fusion a viable source for commercial, large-scale energy production .. this is only tangential at best to that effort. The problem with celebrating "fake victories" (and being scolded for calling them out) is that when there really i…

Another danger: I've seen quite a few people arguing in (a European context) that we shouldn't build out nuclear in the "short term", "since we can just get fusion without any of the downsides of fission".

I've seen also people arguing that we should never ever build nuclear fission again because it is "bad".

What I want to say is that bad faith arguments will always exist, and calling this a breakthrough won't significantly increase the number of people using bad faith arguments, because they would just find another excuse instead of the fusion one.

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

#96

Post by headsoup »

sigmoid10 wrote: post #86
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,…

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?

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

#97

Post by HPsquared »

sigmoid10 wrote: post #86
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,…

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…

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).

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

#98

Post by HPsquared »

est31 wrote: post #87
DecoPerson wrote: post #67

Earlier quoted context omitted.

But it’s software defined, so it’s much quicker to work around failures of those centralised points.

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).

That is, unless the water pipes require internet to work.

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

#99

Post by arethuza »

denton-scratch wrote: post #75
arethuza wrote: post #18

Earlier quoted context omitted.

Most bomb designs are fission-fusion-fission - most of the energy comes from the fission of the casing of the secondary by neutrons from the fusion process in the secondary. Edit: Mind you - there were tests like the huge Tsar Bomba that de-rated at 100+ Mt design to 50Mt be leaving out the final fission stage - the output being mostly from fusion. https://en.wikipedia.org/wiki/Tsar_Bomba

My understanding is that what you're referring to as a "fusion" stage is really a fusion-enhanced fission stage. All the stages of normal "H-bombs" are fission stages, using a small fusion core to generate a flood of neutrons, which results in the fission fuel combusting more completely. Pure fission bombs tend to disintegrate long before enough neutrons have been generated to achieve complete combustion. The inclusi…

"fusion-enhanced fission stage"

The primary is fusion boosted fission, the core ("spark-plug") of the secondary is also fusion boosted fission surrounded by dry fusion fuel (lithium deuteride) and then a fissionable tamper.

My understanding is that X rays from the primary compress the entire secondary package - which ignites the spark-plug and then the fusion fuel is caught between the incoming tamper and the exploding spark-plug at its core and ignited.

So there does appear to be a real "fusion" stage - with a lot of other steps involving fission and fusion.

https://en.wikipedia.org/wiki/Thermonuclear_weapon

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

#100

Post by oblio »

noobermin wrote: post #92
est31 wrote: post #87

Earlier quoted context omitted.

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).

Yeah, I'm not talking about broken facebook or twitter, I'm talking about the various cdns out there, cloudfare, etc

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.

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