[HN Gopher] Nuclear-fusion lab achieves 'ignition': what does it...
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       Nuclear-fusion lab achieves 'ignition': what does it mean?
        
       Author : SiempreViernes
       Score  : 140 points
       Date   : 2022-12-13 17:15 UTC (5 hours ago)
        
 (HTM) web link (www.nature.com)
 (TXT) w3m dump (www.nature.com)
        
       | already wrote:
       | More discussions: https://news.ycombinator.com/item?id=33971377
        
       | carabiner wrote:
       | Never thought I'd witness a resonance cascade... Let alone,
       | create one.
        
       | rs_rs_rs_rs_rs wrote:
       | Call me a cynic but the only meaningful thing out of this is that
       | they got their funding secured.
        
       | cpleppert wrote:
       | "To demonstrate that the type of fusion studied at NIF can be a
       | viable way of producing energy, the efficiency of the yield --
       | the energy released compared to the energy that goes into
       | producing the laser pulses -- needs to grow by at least two
       | orders of magnitude."
       | 
       | Lots of claims on HN that we were one order of magnitude away.
       | Similar claims were made in other threads made about how we were
       | really close to commercialization with better lasers. This
       | article has the right take, this research is valuable but its
       | impossible to say anything about whether indirect intertial
       | confinement fusion is commercially viable. Best case scenario
       | [1], we still have a way to go.
       | 
       | [1]: An Assessment of the Prospects for Inertial Fusion Energy
       | (2013)
        
       | olliej wrote:
       | It's really stretching things to say it produced more energy than
       | went into the reaction.
       | 
       | Energy in:energy out is a ratio of the amount of energy that goes
       | in, not the portion of the energy that eventually hits the
       | target. It's like measuring car engine efficiency by measuring
       | how much of the energy reaching the wheels translates into motion
       | - and ignoring the massive losses that lead up to that point.
        
       | teach wrote:
       | This article was a welcome relief after many of the others the
       | past couple of days. Well-written, clear, optimistic but not
       | hand-wavy, and certainly not "breathless" or loaded with PR.
        
       | isoprophlex wrote:
       | So, they generated 3.15 MJ energy from the target, at a cost of
       | an input of 2.05 MJ laser light. Pretty exciting.
       | 
       | However those lasers aren't very efficient, generating the 2.05
       | MJ required more than 300 MJ of electricity.
       | 
       | What is the path forward... Can anyone elaborate? Do we make the
       | lasers 100x more efficient? Will hitting a target with a 100x
       | mass yield 315 MJ?
       | 
       | Edit: thanks everyone for the clarification. Really helps me
       | putting the numbers in context.
        
         | femto113 wrote:
         | Scaling the NIF's approach (laser inertial confinement) isn't
         | about more reaction mass per pulse, it's about more frequent
         | pulses, and is probably not going to be practical or cost
         | effective in the foreseeable future. The fuel pellets are tiny
         | (~2mm), their container is only about 1cm and must be nearly
         | perfectly spherical. A continuous power plant would consume
         | about half a million of them per day (6 per second), all of
         | which need to be shot with perfect timing, precision, and
         | reliability to the exact center of the laser sphere. My guess
         | is magnetic systems are much more likely to ever be used in
         | power generation.
        
           | laweijfmvo wrote:
           | This feels important. We already know that fusion "works"
           | (proof: look up). But it's not possible to recreate the
           | conditions of a star on Earth. So if this method is also
           | impractical, why would I care that it "works"?
        
             | MattGrommes wrote:
             | If you create an impractical mechanism to prove out a
             | scientific problem, you know it's then worth trying to fix
             | the impractical mechanism. Maybe they start working on a
             | way to direct the pellets into the correct path using
             | magnets or something. But if you don't even know the
             | scientific part works it's not worth going after the magnet
             | solution.
        
             | api wrote:
             | It proves that net positive fusion is achievable here with
             | known physics and technology (outside bombs which are
             | useless).
             | 
             | We had never done that before.
             | 
             | This will probably unlock more funding. In the end a
             | different approach is probably more likely to lead to a
             | power plant unless truly gigantic advancements in laser
             | efficiency can be achieved.
        
             | femto113 wrote:
             | Scientifically it's potentially very interesting: close up
             | observation of what's going on in the center of a star and
             | all that. I'd ignore all "the future of free clean energy
             | is upon us at last!" hype. That's the lab and the
             | government officials trying to drum up publicity that can
             | then be milked for financial/political capital (it costs
             | many billions to build and run a facility like this),
             | coupled with lazy news outlets trying to milk
             | sensationalist headlines for eyeballs.
        
               | TheOtherHobbes wrote:
               | This seems far more credible than the "This means fusion
               | in ten years!" hot takes, which are - frankly -
               | completely implausible, whether they're coming from
               | physicists or journalists.
               | 
               | Weapons research might be a motivator too.
               | 
               | I would be astounded if this can be commercialised. Not
               | because I'm cynical for the sake of it, but because I
               | cannot in good faith see a credible engineering path
               | which might make that possible without spectacular
               | breakthroughs in a number of disciplines.
               | 
               | MCF seems more likely to get somewhere. But my best guess
               | is that advances in renewables will have made fusion
               | redundant within ten years. There is _far_ more scope for
               | incremental and affordable improvements in collection,
               | distribution, and storage than there is for the Big
               | Science breakthroughs required to build one commercially
               | viable ICF plant.
        
         | [deleted]
        
         | teach wrote:
         | Apparently the semiconductor industry already has lasers that
         | are 20x more efficient than what was used in this experiment.
        
           | isoprophlex wrote:
           | Interesting, thanks! So the low laser efficiency isn't really
           | important in interpreting the importance of this news.
        
           | adrian_b wrote:
           | The semiconductor lasers cannot produce pulses short enough
           | for such applications.
           | 
           | They can be used only as the pumping sources for the solid-
           | state lasers or fiber lasers that can produce the short
           | pulses.
           | 
           | So the efficiencies of two lasers must be multiplied. I doubt
           | that there is any chance to obtain an electrical to light
           | conversion efficiency above 10%.
           | 
           | So the energy generated by the fusion reaction should be much
           | greater than 10 times the light energy, to be able to produce
           | excess energy, even with lasers 10 times more efficient than
           | now.
        
           | dark-star wrote:
           | Even if semiconductor lasers could put out the power required
           | (they can't...), a 20x improvement would still mean the
           | efficiency is only around 20%, so you'd still be putting in
           | 10 MJ to get out 2 MJ...
           | 
           | Yes, it's better, but the argument still holds
        
         | lordnacho wrote:
         | I don't get it. Wouldn't that mean it required 302.05MJ to get
         | 3.15MJ?
        
           | mikeyouse wrote:
           | 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.
        
           | OkayPhysicist wrote:
           | 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 wrote:
             | Aha that makes sense, it's a jumpstart basically?
        
               | ep103 wrote:
               | proof of concept, yeah.
        
           | giblfiz wrote:
           | 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 wrote:
             | 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.
        
           | teach wrote:
           | 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!
        
             | WithinReason wrote:
             | >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-
             | nucle...
        
               | falcor84 wrote:
               | 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 wrote:
               | 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 wrote:
             | 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.
        
             | JumpCrisscross wrote:
             | > _" 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.
        
       | ZeroGravitas wrote:
       | This means we might have power as cheap and plentiful as solar
       | and lithium batteries are today in a couple of decades, when
       | solar and Batteries will be even cheaper.
        
       | jujube3 wrote:
       | https://backreaction.blogspot.com/2021/10/how-close-is-nucle...
        
       | didibus wrote:
       | > The US$22-billion ITER project -- a collaboration between
       | China, the European Union, India, Japan, Korea, Russia and the
       | United States -- aims to achieve self-sustaining fusion, meaning
       | that the energy from fusion produces more fusion
       | 
       | It's refreshing to see collaboration like this still happening,
       | even with all the tensions between all those countries.
        
         | coolspot wrote:
         | It was happening for decades. Unclear how the war affects it
         | now, but I believe most RU hardware (cryo and magnets) was
         | already delivered/installed.
        
       | [deleted]
        
       | moloch-hai wrote:
       | It is not a nuclear-fusion lab. It is a nuclear-weapons lab. What
       | it means is they got a better system to model weapons.
       | 
       | What it means to DoE higher-ups is that if they paint it as a
       | breakthrough in energy production, they can unlock funding
       | increases. So they do.
        
       | habibur wrote:
       | In more human terms :                   They fused in 0.6 kwh
       | energy.         Which produced 0.9 kwh energy.
       | 
       | These megajouls are confusing for me. kwh is what we use for
       | resident home power billing unit.
        
         | moloch-hai wrote:
         | Moreso: they managed to put in 0.6 kWh of the highest grade of
         | energy imaginable, and got out 0.9 kWh of hot neutrons, the
         | lowest grade of energy imaginable (short of neutrinos).
        
         | freedom2099 wrote:
         | Joules it's a pretty fitting unit... we are talking about
         | energy in the form of heat here... kWh is a u it used for
         | electricity! Didn't you study physic in high school?
        
           | habibur wrote:
           | Peace.
        
           | fsh wrote:
           | In Europe, kWh is used for both your heating bill and your
           | electricity bill. Since kWh and Joule are two different units
           | for the exact same physical quantity, they can be used
           | interchangeably.
        
           | mettamage wrote:
           | > Joules it's a pretty fitting unit... we are talking about
           | energy in the form of heat here... kWh is a u it used for
           | electricity! Didn't you study physic in high school?
           | 
           | I'd rephrase this to: Joules it's a pretty fitting unit. We
           | are talking about energy in the form of heat here, kWh is a u
           | it used for electricity.
           | 
           | The question at the end comes of as potentially
           | condescending. I'm not sure if you're aware, which is why I'm
           | mentioning this rephrase.
        
             | freedom2099 wrote:
             | I was being condescending!
        
               | [deleted]
        
               | michaelmrose wrote:
               | You could communicate as much without the last insulting
               | sentence delivered for no particular purpose. It elevates
               | the discussion and keeps you from ending up banned.
        
       | dvh wrote:
       | Can someone calculate how much installed solar power could we get
       | by pausing fusion r&d for the next 10-20 years?
        
         | SoftTalker wrote:
         | Not enough.
        
         | coolspot wrote:
         | About zero if China refuses to sell us solar panels due to some
         | conflict.
        
       | phtrivier wrote:
       | Informative and sobering. That's what we need, not press
       | conferences.
        
         | AnimalMuppet wrote:
         | I don't know. This is not "we're there", not by a long shot.
         | But it still seems to me to be worth throwing a lot of confetti
         | over.
        
       | choeger wrote:
       | If I am not mistaken, there is also no current technology to
       | actually _harvest_ that energy, right?
       | 
       | So the lasers need at least 10x the energy they themselves put
       | into the target. Conversion is still unclear. Are we even at 1%
       | to a demo reactor, let alone a commercially viable one?
        
       | zbobet2012 wrote:
       | This is the third thread today with pithy "this means nothing
       | takes". If you're thinking of posting a one liner on the subject
       | you should probably stop.
       | 
       | Let's save some time out of discussion now:
       | 
       | 1. The lasers at NIF are not designed to be efficient, and they
       | are very old. Modern semiconductor lasers are 20x more efficient.
       | The 300MJ wall plug conversation is stupid, stop pointing it out.
       | 
       | 2. Dropping crystals and hitting them with lasers is not hard, we
       | do it in semiconductors for EUV light source generation all the
       | time. In fact EUV light sources do it at 100khz or more.
       | 
       | 3. Power extraction from a bundle of hot material is not a
       | particularly unknown problem. It's in fact how every power plant
       | on the planet works.
       | 
       | Make no mistake there are a lot of engineering problems to solve.
       | The "droplets" are enormously expensive, the "firing" itself
       | creates debries which need cleared from the chamber, dt supply is
       | not something that's readily available in large quantities, blah
       | blah. I'd love interesting conversation about what stands between
       | ICF and a real energy plant, not hot takes.
        
         | Gwypaas wrote:
         | > 3. Power extraction from a bundle of hot material is not a
         | particularly unknown problem. It's in fact how every power
         | plant on the planet works.
         | 
         | Coal and nuclear are uncompetitive simply from the cost of the
         | steam side. Today you can just about give a steam plant free
         | energy and it still makes a loss.
         | 
         | Solar or wind does not have this limitation. CCGT gas plants
         | gets around it by having a turbine giving raw mechanical power
         | and then utilizing the same awful steam side to get the last
         | percentage points of efficiency at a much smaller required
         | scale.
         | 
         | Unless you can step around the steam turbine I do not see this
         | becoming anything outside of incredibly small niches.
        
           | Gud wrote:
           | Neither coal nor nuclear are uncompetitive.
        
             | Gwypaas wrote:
             | Compare newly built renewables with all costs included to
             | the marginal cost of paid of coal and nuclear. [1] Today it
             | is often better to simply shut down your existing nuclear
             | plant and build a renewable instead. For a more
             | comprehensive look see [2].
             | 
             | [1]: https://www.lazard.com/media/451885/grphx_lcoe-07.png
             | 
             | [2]: https://www.lazard.com/perspective/levelized-cost-of-
             | energy-...
        
               | kube-system wrote:
               | Looks like you'll pay the same price if you shut down an
               | existing nuclear plant for wind/solar, unless you can bag
               | some subsidies.
        
           | gpapilion wrote:
           | I reckon solar is competitive in the day time without storage
           | or peaker plants to support low generation time. I'd love to
           | see the analysis of solar with the built in assumption of
           | burdening the hourly cost with the infrastructure required to
           | generate the required power at 10pm.
        
             | Gwypaas wrote:
             | The generation during the day will not be burdened by that
             | infrastructure. The night time generation will simply be
             | day time cost + infrastructure.
             | 
             | Theoretically, you can bet that your traditional power
             | plant only runs at night. But now your capacity factor is
             | less than half the available hours for the same capital
             | investment and it looks even bleaker.
        
               | gpapilion wrote:
               | This is where I think it probably should be. Solar w/o
               | another generation or storage source doesn't accurately
               | represent the full picture of what is really required to
               | support the a whole day of electricity. So the combined
               | total cost is probably what should be shown to represent
               | the costs of a full day cycle of solar, or a rainy day.
        
         | fuckHNtho wrote:
         | My cynical take is a lot of people are subconsciously unhappy
         | with how BS and mundane their "tech" jobs are. They chose
         | money+cool, only it turns out the 'cool' part was a lie to get
         | them to churn out as much useless BS work as possible. So they
         | get through the day by fooling themselves: slap a cool tech
         | name on your product, make trendy graphics ( https://traefik.io
         | https://github.com ), pretend you're doing some sci fi shit.
         | Then any real tech happening in the world exposes your BS so
         | you need it to be framed as a disappointment.
        
           | aidenn0 wrote:
           | I'm 42 and there have been "breakthroughs" in fusion
           | announced at least once per decade of my life. There's a very
           | real chance that this breakthrough means the first fusion
           | power plant will open after I'm dead, as none of the men in
           | my family have reached 80.
        
             | dotnet00 wrote:
             | So, the issue is that the community here has grown old,
             | cynical and unable to appreciate anything that might only
             | help the next generations?
        
               | malwrar wrote:
               | No, the community here is skeptical of science reporting
               | that seems too good to be true and progress in fusion
               | energy production fits the mould. I'm not an expert on
               | fusion or the physics, so the best I can do is agree with
               | this sentiment and note details from skeptical comments.
               | 
               | Hey, if we're wrong life will change for the better for
               | billions of people. I like being surprised with good news
               | more than disappointment.
        
         | jjtheblunt wrote:
         | > Power extraction from a bundle of hot material is not a
         | particularly unknown problem. It's in fact how every power
         | plant on the planet works.
         | 
         | River power spinning a generator? Wind farm power? Are those
         | counterexamples?
        
           | falcor84 wrote:
           | Well, these aren't "bundles" per-se, but as I understand it,
           | both are relying on the Earth-as-a-system converting heat
           | from the sun falling on particular areas into large-scale
           | flows, which we humans can then hook into.
        
           | manmal wrote:
           | GP was likely referring to power plants that burn things in
           | order to heat up water to make steam in order to rotate an
           | iron core encircled by copper wire. Using kinetic energy like
           | wind or flowing water is a nice shortcut to the rotating iron
           | core. Even nicer: Cut out the rotating iron core and directly
           | produce voltage via photons hitting a semiconductor.
           | 
           | I share GP's sentiment though that, in the end, there are
           | remarkably few concepts at the bottom layer of electricity
           | production.
           | 
           | (There are other means of course, but they are not in use for
           | power generation in amounts that can drive even one
           | household, AFAIK)
        
         | jboy55 wrote:
         | The problem I have with this announcement is how limiting this
         | technology path is to the future generation of power. If you
         | look at the details, they imploded a sphere containing hydrogen
         | with X-rays created by the interaction of the lasers with an
         | outer casing. As a reminder, the second stage of an hbomb is
         | the implosion of a cylinder of hydrogen, encased by uranium, by
         | x-rays ablating the outer case. X-Rays produced by the
         | explosion of a A-Bomb. The lasers are thus serving as a proxy
         | for the first stage of a H-bomb.
         | 
         | The critical question, how much of this design is to figure out
         | how to produce energy from fusion with the aim of powerplant
         | design, and how much of the design is to better replicate the
         | second stage of a h-bomb?
         | 
         | Edit: I'll have to research, but I would have to expect that
         | the announcement of the h-bomb had language that also heralded
         | this as the beginning of a 'fusion age' of power generation.
        
           | Gibbon1 wrote:
           | Sketch thing is that perhaps they're try to design an
           | hydrogen bomb that doesn't require a fission primary. Use a
           | laser to ignite the first stage, which ignites the next and
           | so on. What if you can get 100X boost per stage, three stages
           | gives you a gain of 1 million.
        
             | jboy55 wrote:
             | There is just basic h-bomb efficiency gains here. By
             | lowering the energy requirement for the fission primary by
             | finding more efficient ways to control/generate the X-Rays
             | you can use a smaller and smaller primary. It also occurs
             | to me how analogous this research is to the early x-ray
             | laser tech, that Teller claimed could shoot down warheads
             | for the Star Wars program in the 80s. Those designs had
             | rods that would amplify and focus the x-rays from a nuclear
             | bomb on incoming warheads. If you could initiate the x-ray
             | chain reaction from a laser, you would be able to launch
             | these without breaking the 'no nuclear weapons in space'
             | treaty.
        
         | cpleppert wrote:
         | The studies done ten years ago suggested that the best case
         | scenario was about thirty years( one demonstration phase of 15
         | years and another development phase of 15 years). This was
         | premised on the INF demonstrating ignition using indirect drive
         | soon after operation. There was also an expectation that the
         | INF would transistion to researching other, possibly more
         | promising technologies like direct drive ignition.
         | 
         | Instead, it took over ten years to simply demonstrate ignition
         | using the indirect drive method which was chosen specifically
         | because it was seen as being more technologically viable. This
         | "big breakthrough" was supposed to happen immediately after
         | operation!
         | 
         | No one knows whether commercialization of inertial confinement
         | fusion is even possible. Laser efficiency is just one small
         | part; the work to produce and develop a system to reliably
         | shoot hohlraum targets is an order of magnitude harder than
         | shooting a static target in ideal conditions.
         | 
         | Compared to these engineering challenges demonstrating ignition
         | is the easy part.
        
           | zbobet2012 wrote:
           | > Compared to these engineering challenges demonstrating
           | ignition is the easy part.
           | 
           | Again, let's discuss what those challenges are. A bunch of
           | talk about how hard it might be with no detail on what makes
           | it hard isn't really informative to anyone.
           | 
           | > the work to produce and develop a system to reliably shoot
           | hohlraum targets is an order of magnitude harder than
           | shooting a static target in ideal conditions.
           | 
           | Please see my note #2 about EUV light sources and similar
           | technology. My understanding is the timing and precision
           | requirements are much higher here, but on the other hand the
           | "rate" of fire would be necessarily much lower making
           | something perhaps feasible.
           | 
           | From the presentation and panel today, one of the key drivers
           | seems to be the purity of the capsules and the ability to
           | correct for asymmetries in the implosion caused by them. The
           | results announced today where not because of the purity of
           | the capsule, but instead because of the correct prediction of
           | the asymmetries in the implosion and the ability to counter
           | that with modifications to the laser strength and timing.
           | 
           | The NIF isn't (as others have noted) necessarily focused on
           | bettering these two factors.
           | 
           | What I'd like to understand is what are the major tradeoffs
           | in ICF vs MCF that would drive pursuing the difficult
           | engineering problems of one vs another.
        
             | cpleppert wrote:
             | >> My understanding is the timing and precision
             | requirements are much higher here, but on the other hand
             | the "rate" of fire would be necessarily much lower making
             | something perhaps feasible.
             | 
             | Leaving aside rate of fire and energy efficiency you have
             | to develop a system that can shoot the hohlraum into the
             | reactor chamber such that the lasers can be steered onto
             | the target with enough precision to produce ignition. I
             | believe 100um is the miniumum for the type of targets used
             | in the INF. This all needs to occur within the reaction
             | chamber. Besides the thermal loads you also have residual
             | gases within the chamber. These conditions somehow have to
             | be accounted for or you won't get ignition.
             | 
             | The work they did in demonstrating ignition is great but
             | the engineering challenges for commericalization are
             | immense. EUV lithography took decades to develop and
             | perfect.
             | 
             | >>What I'd like to understand is what are the major
             | tradeoffs in ICF vs MCF that would drive pursuing the
             | difficult engineering problems of one vs another.
             | 
             | MCF is generally seen as a much easier approach because you
             | avoid the problems with repeatedly generating fusion
             | conditions and you remain in the ballpark of what can be
             | solved with better technology. You can come up with a
             | tokamak that you can be absolutely sure will probably work
             | with enough money; but I'm not sure the same is true with
             | ICF.
        
               | zbobet2012 wrote:
               | https://www-
               | pub.iaea.org/MTCD/Publications/PDF/TE_1704_web.p...
               | 
               | and
               | 
               | https://www-
               | pub.iaea.org/MTCD/Publications/PDF/TE-1911_web.p...
               | 
               | actually layout some of the challenges. they are not as
               | you state and there ARE tradeoffs between MCF and ICF.
               | Most experts agree MCF is closer to realization, but
               | that's a very well educated guess not a surity.
        
       | everyone wrote:
       | I read a comment here before saying that the purpose of the NIF
       | is to get more data for making hydrogen bombs, while being unable
       | to test actual bombs due to treaties. And that the press releases
       | they have about fusion energy are mainly bullshit for the press.
       | 
       | Is there anything to that claim or is _it_ bullshit?
        
         | dotnet00 wrote:
         | Part of their job is to make sure that the nuclear stockpile is
         | still reliable. Since they can't actively blow up a nuke
         | nowadays, they instead rely on experiments and simulation.
         | 
         | However, like a lot of the Department of Energy's work, their
         | nuclear research also relates heavily to civilian applications.
         | They are not 'bullshit' for the press.
        
       | dougmwne wrote:
       | "However, while the fusion reactions may have produced more than
       | 3 megajoules of energy -- more than was delivered to the target
       | -- NIF's 192 lasers consumed 322 megajoules of energy in the
       | process."
       | 
       | Well that says it all right there and really cuts through all the
       | fluff on this story. Sounds like a nice milestone that has
       | absolutely nothing to do with our ability to get a useful amount
       | of energy back out. We are still at least 2 orders of magnitude
       | away from a power source.
        
         | sigmar wrote:
         | No one at this lab is saying it is ready for commercial sales.
         | The technical Q&A even featured them saying high energy lasers
         | might not be the best tech for driving the fusion in a
         | commercial setting- https://youtu.be/Eke5PawU7rE?t=5250
        
         | dahfizz wrote:
         | We already have lasers which are an order of magnitude more
         | efficient than the one the lab was using. This is about a proof
         | of concept, not about being an actual power plant.
         | 
         | Also, as I understand it, the whole thing scales up very well.
         | Now that we can "ignite" fusion in the little pellet used for
         | testing, we can scale up to ignite a larger amount of fuel in
         | order to get out much more energy.
        
         | carabiner wrote:
         | They put 2.05 MJ in and got 3.15 MJ out. The 300MJ comes from
         | equipment inefficiency- remember this is a research facility to
         | prove plasma physics and ignition itself, mainly designed for
         | weapons research. The fact they got definite fusion at 1.53x
         | input energy is not just breakeven, but net gain. This is the
         | first time _ever_ we 've gotten net gain, in any fusion device.
         | A lot of people in gov leadership thought fusion was
         | impossible, the fact they can said they did it, despite 1980s
         | era technology and a shoestring budget for decades, really says
         | something.
         | 
         | ICF is just one fusion technology, and probably not the best
         | one, but fusion in general will probably see a massive budget
         | increase worldwide now that it's been proven it can be done.
         | 
         | I fully expect a working fusion plant of some kind by 2030,
         | assuming funding increases. Once we get them commercialized;
         | coal, wind, solar and other power production will be obsolete
         | for the most part. We can also use fusion heat to separate
         | waste into it's base elements (you can recycle anything!), and
         | help make any process needing a lot of thermal or electrical
         | energy more efficient.
        
           | boppo1 wrote:
           | How much easier to build and safer are they than fission
           | plants? Otherwise they will still be politically
           | bottlenecked.
        
             | ep103 wrote:
             | IANAScientist, but I believe I read that fusion requires a
             | steady input of energy to continue the reaction. So much,
             | much safer than fission, which is a chain reaction that can
             | go out of control at any time, fusion, you just turn off
             | the power and it stops.
             | 
             | IIRC
        
         | d23 wrote:
         | Do you have a background in this field?
        
           | dougmwne wrote:
           | I do not. I would say if I did.
        
             | d23 wrote:
             | To be blunt then: your comment does not add to the
             | discussion in a substantive way.
        
         | beezlebroxxxxxx wrote:
         | The next steps in the story are, how easy is it to make this
         | process more efficient? Is there something fundamental that is
         | lessening the efficiency, or is it a matter of needing to buy
         | part X or laser X or variant y to improve efficiency?
         | 
         | Most research achievements are wildly inefficient because
         | efficiency is not really their goal, they're looking for proof
         | of concept. Once the concept is proven, you step into a whole
         | different ballgame when efficiency is the goal. (Hopefully, who
         | knows.)
        
           | rini17 wrote:
           | There's a reason for optimism as for the lasers' efficiency.
           | But there are many other aspects that were only approached
           | theoretically so far, such as how to get useful energy out of
           | the reactor.
        
         | simplicio wrote:
         | Not useful for commercial energy production, but useful if you
         | want to study self-propagating fusion explosions in a bomb,
         | which is the actual purpose of the facility.
         | 
         | NIF is really confusing the issue (I think this is the first
         | pop-sci article Ive seen that even mentions nuclear weapons,
         | and its relegated to one sentence surrounded by discussion of
         | commercial energy). They're (justifiably) excited because after
         | a decade of trying, they've finally managed to fulfill the
         | facilities primary purpose and recreated an important aspect of
         | the conditions inside a thermonuclear bomb.
         | 
         | But they're obviously reluctant to foreground the bomb stuff,
         | so instead they hand-wave in the direction of energy
         | production, which doesnt make a lot of sense, and leads to a
         | lot of folks pointing out that the energy needed to get the
         | reaction going is more then just the laser pulse itself, which
         | would make a big difference for commercial production, but
         | doesn't really matter for the experiment theyre trying to
         | perform
        
         | TheCondor wrote:
         | This is closer to pure science. This is in a lab. They aren't
         | even attempting to make a "power source" so much as testing and
         | verifying the theory.
        
           | dougmwne wrote:
           | And that is great! My issue is the way the science is
           | reported in the media making it sound like we are on the cusp
           | on some kind of energy revolution, when we very much are not
           | and don't even have a line of sight on it yet. But then I
           | suppose public hype will lead to Congress dollars and nothing
           | gets done without those.
        
             | TheCondor wrote:
             | Seemed like this article in Nature did pretty good. They
             | explicitly said: "I don't want to give you a sense that
             | we're going to plug the NIF into the grid: that is
             | definitely not how this works," and "Although positive
             | news, this result is still a long way from the actual
             | energy gain required for the production of electricity,"
             | said Tony Roulstone, a nuclear-energy researcher at the
             | University of Cambridge, UK, in a statement to the Science
             | Media Centre.
             | 
             | Still, "the NIF experiments focused on fusion energy
             | absolutely are valuable on the path to commercial fusion
             | power", says Anne White, a plasma physicist at the
             | Massachusetts Institute of Technology in Cambridge.
             | 
             | There is a pretty solid disconnect between the public's
             | perception of how science works and happens and how it
             | does. For this to really matter, someone else needs to
             | duplicate the experiment and verify the data. It's a huge
             | win if the hype can lead to that.
        
       | cainxinth wrote:
       | It means practical fusion power, which has been 20 years away for
       | the last 60 years, will now be just 10 years away for the next 30
       | years.
        
         | trhr wrote:
         | Followed, of course, by being 5 years away for the next hundred
         | years.
         | 
         | Big oil is much more competent adversary than science.
        
         | MichaelZuo wrote:
         | Well not even that, there isn't even a roadmap to improve laser
         | efficiency 100x
         | 
         | Even a 90% efficient high powered laser is way beyond fusion in
         | terms of technical difficulty.
        
           | pdabbadabba wrote:
           | But am I wrong in thinking that it's conceivable that we
           | could see a further doubling in Q-plasma? If that happens,
           | perhaps along with significant-but-plausible improvement in
           | laser efficiency, then things could start to look fairly
           | promising.
        
             | MichaelZuo wrote:
             | Did you reply to the wrong comment?
        
               | pdabbadabba wrote:
               | Nope! My point was that your comment assumes no further
               | increase in Q-plasma. But the experience of the last few
               | years suggest that there's reason to hope that won't be
               | the case. We can come at the problem from both sides.
        
         | crispyambulance wrote:
         | Didn't someone the same thing about atomic power back in the
         | middle ages?
         | 
         | But that's OK, fusion is a hard thing to do outside of a star.
         | It may take decades longer for it to be practical but doesn't
         | the potential return on investment make it worthwhile to keep
         | working on it now?
        
       | androtech wrote:
        
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