Is nuclear fusion poised to deliver? | Hacker News Reader

Is nuclear fusion poised to deliver?

theguardian.com

121 pointstilt114 comments

I saw a guy called Dennis Whyte from MIT give a shockingly bullish fusion presentation a few weeks ago.

His view is that new superconductors make a compact (as in jet size) reactor that does better than break even and is operable feasible in five years.

He seemed to know his stuff

https://www.youtube.com/watch?v=KkpqA8yG9T4

Ten years ago I was in a set of lectures by one of the ITER consultants. There were a handful of challenges left (e.g. material degradation after long-term neutron bombardment) but it wasn't science fiction then.

The only question was if they could get the funding to finish the last research hurdles.

As the head of one of the most advanced plasma physics labs in the world, I think it is safe to assume Prof. Whyte knows his stuff.

From the video it seemed to be down to the new students coming up with new ideas, and using new technology.

DISRUPT!!!

This is one of the main goals of running these labs, and ideally the main goal of universities in general. Training new minds with the knowledge of the leaders in the fields.

It's not disruption, it's evolution and progress.

Too late to edit. Grammar of my comment is ambiguous/incorrect: Dennis Whyte is the leader of said lab, not me ;).

I watched that video a few weeks ago.

The main issue is that ITER is built and designed using legacy superconductors. Recent developments, and they're ongoing are allowing the designs to be reengineered.

The new superconductors can work with a much higher magnetic flux. There was something about the efficiency of a reactor increasing with the fourth power of the magnetic flux (B^4). And as I said they're still making improvements to superconductors.

Another idea used is FLiBe salt as a coolant. One of the issues with Fusion reactors is that most metals can't withstand the neutron flux. Using a molten salt blanket solves that problem, along with the idea of changing out the insides periodically.

Nuclear Fusion isn't my thing so I may be off of the mark.

Now that's very interesting. The main thing I've wondered about fusion - given the huge size and expense of the ITER reactor, even if they get power-positive, will they ever be able to build and run reactors cheap enough to be competitive with conventional power production, and keep them running for decades?

The first solar-cell or coal-power plant probably wasn't cost-competitive either. ITER is more like a horribly expensive experience, but a worthwhile one in my opinion.

ITER is mostly a let's-get-this-thing-started than a economically viable reactor. ITER forced development is areas direct related to the reactor, as magnets and construction techniques.

I think everyone agrees that ITER as a science platform is fantastic.

I'm finding it difficult to Google how efficiency scales with magnetic flux. I've ended up at a thirty five page pdf https://arxiv.org/pdf/1409.3540. Equation 1 on page 5 states the fourth power dependency. So using REBCO magnets, instead of Niobium-Tin, to get twice the magnetic field looks like a really big deal.

Page 6 adds a twist to the story. "For REBCO superconductors operating far below their critical temperatures, the toroidal field is generally limited by mechancical stress rather than the critical current density, which typically limits standard Nb3Sn." So further increases in magnetic field might be waiting on advances in mechanical engineering design, not on better superconductors.

Really big challenge keeping the magnets from flying apart. They exert absurd forces on each other.

Prof. Whyte thinks that they have that by making really interesting stainless steel coiled tape stuff. I really lost the plot at this point in the presentation and did not understand how it would work, but then he passed round some samples (which could have been anything at all to be fair) so I became convinced that the stainless steal coiled tape approach to fabrication is real and practical.

I think his idea is to make the magnets now, quickly, and use them for things like magnetic resonance scanners. I think that will prove the technology which he then intends to scale to a reactor; and several Ph.D folks are busily designing said reactors.

And even if the strong steel beams hold them initially, the bombardment with the neutrons will weaken them. And then... boom.

Damage from high-speed neutrons is deal killer. Periodically replacing neutron-damage magnets is too expensive.

Another key thing I didn't mention was that at higher magnetic fields they no longer need to worry about plasma instabilities.

I believe quite a lot of work had gone into how to managing instabilities. From the video the more powerful superconductors are supposed to reduced those issues.

Although a Phyics graduate I'm not an expert in nuclear fusion.

They also mentioned that the "magnetic pressure" is the equivalent of 5000 atmospheres, I think I have an idea what they mean.

Taking questions someone asks about modes of failure; however catastrophic structural failure wasn't one of them.

Not a huge deal since there's scant amount of fusion fuel.

This must be the lecture: https://www.youtube.com/watch?v=KkpqA8yG9T4

I'd really would like to know what the German Wendelstein people would do with those better Superconductors. Can you build a smaller Stellarator?

Professor Whyte said yes - he said that they would use the Stellarator design if it made more sense.

Did he mention using a stellarator as oppose to a tokamak? Apparently computer modeling makes a stellarator more feasible and I was wondering if using superconducting materials would make it even more so

Stellarator designs already use superconducting electromagnets.

The newer kind are just a lot more powerful and versatile.

He said that they were watching what was happening with the stellarator design in germany and if it proved out they'd use that rather than a tokamak.

Stellarators have become easier to design, but they're still a complete pain in the arse to build. Wendelstein 7-X was nine years behind schedule and significantly over-budget, mainly due to unforeseen problems in assembling the coils. The National Compact Stellerator Experiment was abandoned in 2008, again due to construction delays.

For stellerators to become viable, we need some major advances in manufacturing technology.

https://en.wikipedia.org/wiki/Wendelstein_7-X https://en.wikipedia.org/wiki/National_Compact_Stellarator_E...

But isn't simpler coil assembly what Mr. Whyte proposes? New Superconductors allow for simpler and more powerful coils, allowing smaller, cheaper designs. That should translate to the Stellarator configuration equally well, or am I wrong?

There is a private company close to me [1] that are working in this area and are also very bullish, I went to a talk there a couple of months ago and they said much the same, five to ten years.

[1] http://www.tokamakenergy.co.uk/

Can you possibly imagine them saying something else?

Big breakthroughs are always "five to ten years away" :-)

If this works, it would sure be good for the environment.

Imagine all the wars when the oil money vanishes from the middle east.

I'm having difficulty. Wouldn't it mostly go back to being a poor desert region?

And how many of them will be "happy" about that socioeconomic change?

Or the largest refugee crisis since the sea people.

It it becomes very cheap, it could change industry.

Could?

An alternative approach to generating power from fusion:

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

"A typical design called for a 4 m thick steel alloy blast-chamber, 30 m (100 ft) in diameter and 100 m (300 ft) tall,[10] to be embedded in a cavity dug into bedrock in Nevada."

It involves dropping H-bombs into holes in the ground - but at least we know those work... :-)

We also have good idea about Thorium reactors. There's plenty of it around, and good reasons to think they'd be safer than our current reactors.

Thorium reactors have no advantage over any other molten salt reactor.

The novelty in thorium isn't the fissile material but then reactor design which isn't novel either it just not a breeder reactor so no one is going to spend billions if when push comes to shove it can't be used to make nukes on the way.

Thorium reactors have no advantage over any other molten salt reactor.

More plentiful fuel?

And a considerably more expensive fuel cycle with breeding being questionable at best.

And you then either have to chose if you are going to irradiate the thorium when you make your fuel without purification which will introduce u232 into the mix which undergoes gamma decay making the thorium fuel very dangerous to handle, or purify it and end up with u233 in the mix which effectively makes thorium a dual use fuel now so all weapon related restrictions apply.

Not compared to fast uranium reactors, which can use all the uranium instead of 0.7% of it. There's a couple times more thorium than uranium on land, but with the resulting efficiency it'd be economical to get the small amount of uranium you need from seawater, which has vastly more. Moltex, Terrapower, and others are working on fast uranium MSRs.

Thorium can't be made into a bomb, so there's one advantage.

That depends on perspective. Probably a big disadvantage to the North Koreans.

Ha! Thanks for posting this, I hadn't seen it before. I love the 'go big or go home' nature of the projects that attempt to realize the promise of nuclear power, by simply using nuclear bombs. The famous example being nuclear pulse propulsion (project orion).

18 billion USD for a fusion reactor.

installed utility solar is right now about $1.50 / watt. The subsidy is 1/3 that. So $0.50 / watt.

$18 billion would incentivize 36 billion watts.

36 GW of fully installed utility solar is about half of all the PV solar installed in the world in 2016.

36GW vs 3GW (iter's 500MW * 6 because the panels provide maybe just 4 hours per day)

I realize fusion may be long term important, so well spent. Just hope people are remembering we've got that big fusion ball in the sky.

I expect my lights to turn on when it's dark or cloudy outside. Fusion facilitates that, solar doesn't (unless we also get breakthroughs in battery tech).

Lighting takes very little power once you switch to LEDs. I replaced all the bulbs in my house a couple of years back, and the total draw - were we to turn all interior and exterior lights on at once - would come in at around 250 watts. This is effectively negligible - the refrigerator alone uses at least twice that much.

In any case, the real answer is not solar by itself, but solar plus other sustainable sources like wind and hydro.

You aren't counting real estate costs, environmental impact, etc.

I'll believe it when I see it. Fusion power is in that bin of technologies/capabilities that are always 20 years away, which includes things like cures for aging and manned missions to Mars.

...or maybe I've just become too cynical.

Aging is a very complex and poorly understood process. Mars has hard physics limitations, though the real limitation is political will.

I'd rank in probability

cure aging < fusion < man on Mars

I would argue that the probability of viable fusion rises faster with funding than does ending the aging process, if we assume that they're both possible. It sounds like fusion is largely a materials problem, where it seems like more funding would let us try more things more quickly (assuming some current underutilization of people who are capable or nearly capable (with some small amount of education and training)), whereas with human body processes, ethical concerns make it largely a black box for more complex functions like aging.

Someone please correct me if I'm way off base here.

The reason it's always 20 years away is because it's chronically under-funded, and always has been.

Sounds like the space program for landing on the moon, until it became a national goal.

I don't recall any timelines like that for a cure for aging. Mars has, but on the other hand, the technology has existed for Mars for a long time, it just never happens because organizations don't want to spend the huge amount of money it would cost. Fusion is different, since it still requires fundamental technological breakthroughs, not just piles of money (although we're getting closer to the "piles of money" phase now).

Fusion being 20 years away was contingent on receiving an appropriate level of funding. Given the funding it's received (below the "fusion never" level), it's exactly on track. In fact, if anything it's ahead of "never" given the advances in superconducting materials we've made, since the director of MIT's fusion program seems to think that we're now only 5 years away from energy-positive fusion.

http://i.imgur.com/sjH5r.jpg (source: https://hardware.slashdot.org/story/12/04/11/0435231/mit-fus...)

MIT director: https://www.youtube.com/watch?v=KkpqA8yG9T4

Manned missions to Mars are also perfectly feasible. Like fusion, we just don't devote enough resources to it.

Pretty much anything space-related would be much easier with two simple steps: first, you build a launch loop to drop launch costs. It's all the capabilities of a space elevator but doesn't require any exotic materials. Launch costs are estimated at ~$3 per kg for a 20GW system, figuring $30B construction cost with 5-year payback if you can hit 100% utilization. And no that's not a typo, that's 5 years to profit at $3/kg - where's Elon Musk when you need him, right? :P

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

http://launchloop.com/LaunchLoop?action=AttachFile&do=get&ta...

Then, you drag an asteroid into orbit and mine it, so you have a bunch of material that's not at the bottom of a gravity well. Both of those steps are in a similar category to a manned mission to Mars - feasible, but would take some serious engineering and serious resources. But once you do them, you also open some serious doors. There is a massive quantity of literally any metal you want in an asteroid. One small rocky asteroid has about 10x the total amount of minerals ever mined on Earth, and why stop at one?

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

Even if we couldn't feasibly return them to earth, they're infinitely more valuable in orbit where they are. We are talking about just a mind-boggling amount of resources exactly where we need them.

If you have large amounts of lead and other radiation-resistant material in orbit you've solved one of the main impediments to a Mars mission, and large-scale space construction in general. Then it just comes down to lifting enough fuel to get you on your way, or finding a way to refine it in orbit.

Heck, you can even use the husk of the asteroid itself as an Aldrin cycler. You kit it out as a radiation shelter, then you can put it on a periodic orbit that will make a 146-day trip to Mars every 2 years and then you never have to touch it again, you just dock your payload to it and ride it along. That way you don't need to accelerate and decelerate all the mass of your radiation shelter every single trip. There are even some orbits that will make faster trips (but less frequently)

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

Another possibility you open up there is using some of a rocky asteroid's uranium for nuclear-thermal rocket engines. The problem with them has always been that nobody wants to use them for takeoff, or even really risk lifting them off with a regular rocket. But if you source uranium in orbit, that problem is solved. Firing them in orbit is still kinda questionable, but it's much more plausible to be able to give them a good kick to build distance if you're not starting from a terrestrial launch. Having orbital infrastructure just makes everything so incredibly much easier since you are saving at least 2 stages, maybe three.

Nuclear-thermal rockets use hydrogen as a reaction mass, which you may know as "the most abundant element in the universe". Ramscoops could even allow such craft to have a plausible mechanism to acquire more fuel (reaction mass, technically) on long-duration or interstellar missions. You could even combine nuclear thermal propulsion to get you up to ramscoop speeds, switch to ramjet for cruising, and then brake on the nuclear-thermal engine again - all on a single fuel source.

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

Viable interstellar probes are the marquee selling point of the uranium, but of course you would also be able to power reactors in orbit to run all this infrastructure, breed more Pu-239 for RTGs for probes safely in orbit without the risk of a launch accident, etc.

At this point the solutions exist on paper to go anywhere we want within our solar system, and even start exploring beyond. You can even make it pretty easy by laying down this infrastructure. But we could do it the hard way right now as well, if we wanted to. There's nothing stopping you from using big rockets to lift big parts into orbit and then assembling a huge ship suitable for a long-duration interplanetary mission. We just don't want to. Bummer, especially since we could get unlucky tomorrow and have another K-T extinction event.

Aging is a tough nut to crack and we're not going to plausibly break Death anytime soon (maybe in a few hundred more years - but sorry kiddos, that still means that in the grand scale of the human timeline you still are some of the last people that are ever going to die). But there's animals that are capable of living much longer lives than you would expect, and we can certainly adopt some of their mechanisms for maintaining genetic homeostasis. There's no reason to think that our current lifespan is the limit, after all people living to 100+ was absurd not too long ago. Nature and science undoubtedly still have some tricks up their sleeves.

You don't suddenly discover one weird trick to live forever (doctors hate him!). It's a debugging process, we are going to crack one problem and then move onto the next one, getting a little farther each time as we go. Someone will figure out how to switch cancer cells off, someone else will figure out how to cure dementia, then the average lifespan will start creeping up to 150 years old. At that point the predominant cause of death will shift to skin failure or boneitis or some other failure point, we will spend another 50 years curing that, and the cycle repeats. (a word of warning: do NOT use squirrel bones)

PS: the nutshell on nuclear-thermal engines is that it allows you to finally break the "tyranny of the rocket equation".

Right now the reason space travel sucks is staging. To send a small ship to mars, you need a small rocket. But you have to inject that small rocket into orbit with a medium rocket. And you have to get that medium rocket out of the atmosphere with a large rocket. At each stage, the only way you can gain forward speed is by throwing an equal mass backwards (not quite but works for a description). So to throw a tiny mass where you want it, you need to throw a whole bunch of crap away first to push you. The Saturn-V rocket was more than 90% fuel by weight. Chemical rockets are literally just big gas tanks that you can drop part of when they're empty so you don't have to drag around dead weight, that's it.

Working temperature is an extremely important factor for the specific impulse (thrust per mass of fuel consumed) a rocket generates. The hotter the reaction mass, the more thrust you get out of it. I'll come back to this but the point is you need to heat the gas.

In chemical rockets the energy source and the reaction mass are integral, you burn the fuel and it uses its hot exhaust as a reaction mass. The advantage of a nuclear-thermal engine is that they're separate - with fission/fusion you can heat an immense amount of reaction mass with a small amount of fuel, and you can pick up more reaction mass as you go (via ramscoop). Suddenly the whole picture changes, because you no longer need to lift the skyscraper full of reaction mass that you don't really care about in order to move the tiny spacecraft you do want. As long as you're going fast enough you can ramscoop yourself more from hydrogen that's just floating around space at about 1 atom per cm^3.

Not only that but nuclear rockets get much hotter than chemical rockets and you could produce about twice the specific impulse, making your reaction mass go a lot farther.

Obviously the task of building orbital infrastructure is an immense one. It's a 50-year project, maybe a little less if we pipeline things to push it along. There is a massive amount of R&D that would have to happen, but almost all of the technology described here literally exists today. There are no magic materials we need to invent, it's just engineering the pieces together. We have linear induction motors, we have externally-stabilized supertall structures (antenna towers), we have steam catapults, we have nuclear reactors. We just need to turn them into a launch loop. And you don't even need all that launch capacity, it just makes things easier - Deep Space Industries wants to pull an asteroid in with just small probes, it's just going to take a lot, lot longer. NASA has tested nuclear rockets (NERVA program). etc etc. We would have some work to do on implementing a practical ramscoop, and we would need to figure out how to do mining, refining, and fabrication effectively, but those are relatively discrete tasks that are solvable with current technology, it's just a matter of figuring out what works and what doesn't.

Our children could live in an interplanetary (bordering on interstellar) society if we wanted them to, using shit we've got lying around right now. Our children could walk on other planets and work in space. They could live to see the first pictures beamed back from another solar system, and if not them then their children would.

Throughout history humans have looked up at the stars and wondered what was going on up there. They watched the gods wander the sky, and made up tales of what they might be doing. The truth is that we are a unique generation of human beings, because we are the first humans to ever live who have had the planets and the stars in their grasp and yet turned away. The Greatest Generation didn't. It's really only in the last 20-30 years that we have lost our way, but now it's just perceived as normal. Like the grandparent said - a mission to Mars is just some impossible fantasy that's always 20 years away. The truth is that it's 20 years away because we never bothered to get started. It's the pile of dishes in our sink that we never wash, or the "check engine" light we always ignore. It's always easier to put it off until tomorrow. We're just so busy with [crisis of the day], or the standoff with [enemy of the day], or if there's no crisis then taxes need to be cut and there's just no money left in the budget to spare.

I don't particularly care that the moon landings were done out of a sense of nationalistic dick-waving. We don't refuse to drive on the interstates just because they were built so the military could move troops around during World War 3. We don't refuse to use the Internet just because it was designed as a military command-and-control system. We don't refuse to use computers because they were designed to break military codes and simulate the wing flutter of bomber aircraft and the explosions of nuclear warheads. The history of technological advancement is literally bathed in blood. I don't know for sure but I imagine the first tool humanity ever invented was used to bash someone's head in. The fact that we can reflect on that is the self-awareness we need to come together and make this push for our species' future.

I was actually reading about mining uranium from asteroids recently. It seems like it would be impractical because the chemical processes (involving water) that concentrate uranium on Earth don't operate in asteroids. How does uranium mining and refinement actually work in space?

My theory is that could be the martian "killer app"; shallow gravity well and benign climate (unlike venus) for the industrial processing of asteroid sourced resources.

Probably not poised. At best ITER might show some interesting results, but it's not a cost effective way to build a power plant.

While I would of course be very happy if a workable fusion system ever becomes practical I think there is almost no chance of it happening in my lifetime. Every time there is some positive news like this going back 50 years it turns out that we are still "20 years away".

The article fails to mention the elephant in the room: damage from high-speed neutrons. From https://www.scientificamerican.com/article/can-small-fusion-... Deuterium-tritium fusion releases most of its energy as high-speed neutrons, which damage steel parts and gradually turn them radioactive.

In contrast, much simpler Molten-salt-fueled reactors can burn current stock piles of spent fuel rods. Safely generating electricity while reducing nuclear waste. References:

http://en.wikipedia.org/wiki/Molten_Salt_Reactor#Molten-salt...

http://transatomicpower.com/white_papers/TAP_White_Paper.pdf

The molten salt reactor (MSR) in generation IV: Overview and perspectives http://www.daretothink.org/wp-content/uploads/2015/03/serp14...

> “We are convinced we can deliver hundreds of megawatts through Iter,” up to 10 times more energy than is put in, says David Campbell, the director of science and operations at Iter (which means “the way” in Latin).

That doesn't sound great to me.

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

I'm all for fusion but I think we're some way off it being a staple energy source.

ITER isn't supposed to be a full-scale production plant. It's a reactor specifically to prove that power generation is feasible. DEMO (https://en.wikipedia.org/wiki/DEMO) is the plan for making a practical power station after ITER is done.

Yes sorry my comment was in response to the tone of "poised to deliver?".

Wouldn't that put it on the same level as fission?

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

It actually doesn't matter. It just has to be energy positive and cost competitive.

Take the case of fully tracked wholesale cost of fusion power at $0.01 a kw-h. Would you buy more expensive power just because it had a better EROI?

> It actually doesn't matter. It just has to be energy positive and cost competitive.

Very true.

Maybe I'm missing something but since there's tons of government money going into this, you're not paying the full cost. There's an externality which makes doing the same thing somewhere else unlikely to happen.

Edit: I'm not sure why this is getting downvoted. I'm asking a genuine question. It's not just about energy invested vs. energy harvested. If it costs $100 to build a power plant and you put $1 of energy in and get $2 worth of energy out over its lifetime, you didn't get $2 worth of energy for $1, you got $2 worth of energy for $101.

You'd have to look at the opportunity cost of some other energy technology to know if it was a good investment or not.

Am I looking at this wrong somehow?

I don't know why you were downvoted, but my point was that if it costs less after accounting for the costs you mention, the EROI doesn't matter. That's what I meant by "fully tracked".

If it costs less after accounting for construction and decommissioning costs, then the EROEI is in all likelihood quite good. Cost can often be used as a proxy for energy invested, since energy isn't free after all.

Yeah, sorry. That was my mistake. I misunderstood your point.

I think the parent was referring to spending $1 in electricity to generate $2 worth vs. spending $10 in electricity to get $11 worth. Either way you have a net gain of $1 electricity.

As you've illustrated cost of building the power plant certainly matters however it is orthogonal to the discussion being had.

I have more hope in the German fusion reactor that was constructed in 2015. It would provide continus energy output and not the 50 minutes or so outburst of energy of the ITER reactor.

http://newswise.com/articles/pppl-and-max-planck-physicists-...

"Stellarators confine the hot, charged gas, otherwise known as plasma, that fuels fusion reactions in twisty -- or 3D -- magnetic fields, compared with the symmetrical -- or 2D --fields that the more widely used tokamaks create. The twisty configuration enables stellarators to control the plasma with no need for the current that tokamaks must induce in the gas to complete the magnetic field. Stellarator plasmas thus run little risk of disrupting, as can happen in tokamaks, causing the internal current to abruptly halt and fusion reactions to shut down."

None of them are self sustaining or energy positive as of yet.

Fusion works but stellar fusion is effectively powered by gravity, no one knows yet if it will be viable on smaller scales hence why while a lot of process has been made no one has a made sufficient progress to claim they have a working reactor.

You can initiate fusion in your garage making it energy positive even by a small margin is what we haven't really managed to break.

> You can initiate fusion in your garage making it energy positive even by a small margin is what we haven't really managed to break

That is WORLD changing right there. No we don't have fusion, but the sustaining part has come down to possibly just needing Lithium. Now if you look at where we have come from we are getting closer to where we actually will get more energy out and that will be a game changer.

Lithium is for Aneutronic fusion, while this is being researched it's a completely different fusion mechanism than the hydrogen plasma these reactors fuse.

I made a few comments about this in a previous thread https://news.ycombinator.com/item?id=12877466

Lithium is used to breed tritium, which is a neutronic reaction.

Tritium breeding isn't a primary fusion reaction, Deuterium-Li(6) -> Helium(4) is.

You're thinking of boron.

No, I'm thinking of Lithium.

>no one knows yet if it will be viable on smaller scales

If? I never thought there was any doubt that it can be made viable with sufficient research. The problems are related to when/if we actually do that research.

There is MASSIVE amounts of doubt. We don't know. That's why ITER is being made in the first place. And the cost and build time has been staggering for a test platform.

We've done the reactions, we 'just' need to hold them together for longer. Why is that in doubt? Can you link something by an expert that doesn't think it's guaranteed to be possible?

Because we haven't gotten an energy positive reaction and because the reaction efficiency actually goes down the longer it's going because of how the magnetic flux works in these types of reactors.

There is a huge doubt that this type of fusion can be energy positive at small scales, which is why other types of fusion are being investigated primary aneutronic and ICF based ones.

Aneutronic is pretty interesting because it produces almost no radiation that is directly harmful to living organisms, and ICF (almost has to be at this time) can be scaled down to very small scales, even molecular levels.

Thermonuclear fusion on the other hand isn't a given, it's just the most studied form because it's piss easy to trigger you can build a thermonuclear reactor in your home and produce neutrons which means that fusion is going on, but there is a lot of doubt if it can be scaled to a controlled and energy positive reaction.

The only forms we know of that work is a star which is effectively powered by the force of gravity so it's not necessarily an energy positive reaction in the classical sense or an H-Bomb which requires an energy source that is a not an especially small nuclear fission bomb.

If I would have to make a bet It would be that Beam/ICF fusion and possibly aneutronic fusion when we'll have better hold over nanotechnology will be the energy sources of the future I'm actually somewhat skeptical that thermonuclear fusion will ever become an energy source in the future, even if we figure out that it can be energy positive under controllable circumstances.

Wendelstein 7X is not technically a fusion reactor.

Sure it is. Put deuterium in the reactor and some of it will fuse, and they plan to do that. You can fuse deuterium on a home-built device in your garage, and that's technically a fusion reactor. It won't be a net energy producing reactor, but neither are any of the other devices we've built. We still call them fusion reactors, because fusion reactions happen in them.

It'd be silly not to put deuterium in the 7X, because you get a lot of information by observing the neutrons.

If you have ever wondered about why one goes through the difficulties of the tritium fuel cycle: It's really politically motivated, so none of the participating countries has to rely on an external fuel supply.

If you are depending on ITER to do it, then forget about it. ITER is a money sink. It was designed to suck up as much fusion research money as possible to slow the progress of fusion development.

Don't take my word for it. Go to their website, study the annual reports and time lines, the ever consistent delays, and the mammoth budget and budget overruns. Then go read about the (far too few) more promising experiments in other labs achieved with shoe-string budgets.

"Give it another 20 years" - Said every year since 1980

While funding fell through the floor and came no where near what the recommendation was when those models were developed. Those "in another 20 years predictions" are simple adjusted time lines based on the current level of funding.

Source: https://hardware.slashdot.org/story/12/04/11/0435231/mit-fus...

It's not a failure of the model, and it's unknown if the science failed (as it didn't get a chance to be fully explored), but it's a social/economic/governmental failure. Probably for the same reasons that we are failing to address climate change - in large part, the entrenched interests of existing energy companies.

Can this thing blow up? I mean is there an equivalent in fusion technology to a meltdown in fission tech?

Theoretically yes, every star is a self-sustaining fusion reactor.

However, in practice not because fusion requires much more delicate conditions to work then fission. A breach in the reactor chamber would cause the plasma to quickly expand and cool down, which means the necessary conditions for fusion disappear. Basically fission can cause a self-sustaining chain reaction once started, while fusion requires very specific artificial conditions to be maintained.

More precisely, stellar fusion is self-sustaining because of the immense gravitational pressure. You need around 1/10 the mass of the sun for this to be possible. In the current economic situation, it would be difficult to get funding for a fusion reactor that large.

So Spiderman 2 is wrong then?

https://youtu.be/7OMa51hJOhY?t=42

Exciting times. I'll be watching this, but I'm very curious to see what happens with stellarator designs which appear to be much easier to operate (if massively harder to build).

How do they deal with weather on complex installations this size? I have to imagine some of the equipment they're installing isn't meant to be wet?

My guess is that they first build the concrete support for the instruments, then make a roof, and then bring in the actual instruments.

Much like an ordinary building, I suppose.

5 years ago, I would have thought that ITER is a step in the right direction.

After studying alternative physical model and looking into more logical sun models that explain more while require less assumptions, I came to the conclusion that ITER is the wrong way to go. Dense Plasma Focus is way more promising for hot fusion direction while still not optimal.

What're your credentials?

Or reasoning?

Not the poster but Tokamaks reactors makes energy for maybe 50 minutes at a time before it has to be shut down. This is due to it's 2D magnetic fields.

While Stellarator reactors use 3D magnetic fields in a modulus loop which can have a continuous energy output.

beta factor is bad. stellerator is better, but still wrong approach to fusion. It really depends on the physical model you use - I don't think in the Standard Model anymore - it's falsified and there are better models out there.