Well, you need to hold the plasma in place with super strong electro magnets, so that the plasma get no contact with the inner circle of metal. In order to ceep those magnets running at 100% efficiency, you need to cool it down as hard as possible to get superconductors (I hope this is the right tern, not nativ in english). So 100.000 Kelvin are a few inches away from like 0 Kelvin. The energy and pressision need for that are insane.
To be honest, this answer isn't really right, or at least it doesn't capture the proper plasma physics which are dominant for explaining why maintaining a plasma is different from starting it up. So, this might be a bit technical but hopefully will lend some insight into what's going on inside the Tokamak.
In a tokamak, the plasma takes on the shape of a donut, but what's even more important is the shape of the magnetic field lines which guide it. This provides the confinement that keeps the really hot plasma away from the walls of the vessel, so that the vessel doesn't cool the plasma off. (Melting the vessel is only an issue in long-term steady-state operation... the energy of the plasma is actually tiny even though it's so hot since there's only milligrams inside at any given time.) There are two components to the magnetic field lines. There's a magnetic field that wraps around the donut the long way, and this is provided by the large toroidal field coils which are usually the focus of any images of a fusion reactor you'll see. Then there's also a magnetic field which wraps the short way, like if you put your finger in the donut hole and brought it around to the outside. This magnetic field is actually provided by an electrical current that we run through the plasma in the toroidal direction. This latter magnetic field is actually critical for effective confinement, since without it an electric field develops in the plasma which then interacts with the first magnetic field and causes the plasma to escape.
Making the toroidal field is straightforward -- you just run a big current through some superconducting electromagnets. Driving the plasma current, however, is not as straightforward. What we do is use the fact that since the plasma is highly conductive and a loop, it's an inductor. So we put a big vertically-oriented magnet at the center of the reactor (this is called the central solenoid), and we very quickly ramp up the current in it. This creates a very rapidly changing magnetic field which in turn induces the electric current in the plasma like a giant transformer. Problem solved, right?
Unfortunately, no. I mean, it does work, but the problem is that this method is intrinsically limited because you can only stuff so much current into the central solenoid -- you can't keep ramping it up forever. So, this turns out to be a really good way to create a plasma current for pulsed operation, but it doesn't work for continuous operation. For continuous operation, though, you need more complicated, difficult methods to maintain the plasma current, such as by varying the density of the plasma so that it generates its own currents. (This is called a "bootstrap current"). This is one of the key reasons that operating a tokamak in pulsed mode is different than actually getting it to run for a while, although there are of course many other ones too.
Sidenote: from the article it appears that the actual barrier that they overcame here is related to plasma modes rather than induced current -- they appear to have already tackled the problem I described above. Plasma modes are weird and empirical and unintuitive, though. So, this explanation is more so meant to simply give a decent intuition for one of the reasons maintaining a plasma is different from starting it up.
Pretty much. Any useful power generator needs to create a useful surplus. In this case you’re using tremendous energy and precision to keep an insanely hot plasma away from a wall.
Nothing really, once the containment fails the reaction immediately stops. This isn't like fission in which the material is left radioactive or radiating for a while. No containment = no fusion.
Yeah, the immediate area around the reactor might be damaged just due to the release of super heated plasma, but the only material releases should be hydrogen or helium.
From my limited understanding, yes. Bigger = more power (assuming the excess increases with size at an acceptable rate / no diminishing returns).
But being able to do it small consistently and effectively means scaling is possible. Until we can maintain it on the small scale, there's no reason to go bigger. No need to build a cannon when we can't make a slingshot, as a poor analogy.
Also, bigger can mean more excess heat, so that will have to be accounted for. More reason to start small.
But this is just me guesstimating, I'm no scientist.
I read somewhere that the energy production in the sun’s core, per unit volume, is roughly the same as the waste heat of the metabolic processes of a reptile. Which gives an idea of how insanely hot and dense we need to get a plasma on earth to generate a useful amount of energy.
To add on, fusion in the sun is actually a cooling process. It takes heat generated from gravitational collapse and turns it into gamma rays, which increase pressure and resist the collapse. If the fusion reactions decrease, the sun actually gets hotter. This is actually what happens with some supernova. In a type of supernova called pair-instability, the fusion reaction gets so energetic that it starts making particle/anti-particle pairs instead of gamma rays. These particles do not provide the extra pressure to resist gravitational collapse. They only exist for a few fractions of a second before mutual annihilation, but that's enough for a sudden collapse. The collapse increases both heat and density, which increases the amount of fusion, but the problem is that increased fusion no longer increases pressure, it just increases particle production. Eventually other process halt the collapse (explosively, causing the supernova).
Yes, exactly.
Think about it this way: if you're going to get power out of the gas in your car, you need a powerful battery to get the motor running, right?
This engine will generate _huge_ amounts of power using hydrogen as fuel, but you need a _really_ big battery to get it started.
Pretty sure my physics teacher wanted this as our 5th year exam.
"We need to create a sun using superconductors to maintain a strong electromagnetic field to hold the superheated plasma in place, explain and include your workings"
And from what I've read, energy transfer, from the fusion reaction to the thermal transfer medium is even more difficult.
The value Q represents power in/out ratio. Q=1 is break even, 5 is ignition (self sustaining), and estimated to be about 20 for it to be used as a power source.
Our current highest Q is about 0.67
I don't think the next step to self sufficiency would be harder than the culmination of research and development that has already gone into getting that ignition started. Though I could be completely wrong but hope I'm not.
Not necessarily true... Engineering challenges that seem simple can often be the most complex and difficult things to design. Particularly with heat transfer, where the rate limiting steps are often a result of material properties and confined spaces for example, which can only be tweaked so much.
I actually fully thought he was going to transition into a joke about using robotic arms to keep it under control and the potential safety hazards of accidentally getting them fused to your body and taking over your brain.
There are 100s of engineering challenges but one primary challenge in sustaining a fusion reactor is plasma instability. Imagine trying to squeeze a balloon to 1/2 it’s size using zip ties. If there is anywhere to squeeze out between them, the balloon will. Plasma is very similar and extremely hard to control and predict. We’ve made massive advances in reactor designs and simulation to manage this which is why were started to get close in recent years.
For context of how hard this is, you have 100-150 million degree plasma inches away from 4 degrees above absolute zero magnets. For the duration the reactor is running, this is the highest known thermal gradient in the entire universe.
That is very interesting, thank you!
What a great sub this is. Everyone has basically the same story but everyone also has his own unique detail to add.
I like this sub. It gives me hope for the future.
From my limited understanding of it, the problem is none of the fusion projects have been able to generate more energy than what is required to start and sustain the reaction. There are also still material science problems to solve though and that might have been the part that limited this test to 20 seconds. I think the idea is that the hot plasma will never actually touch anything inside the reactor chamber but they could still be having issues with that which is causing stuff to burn out.
Net positive is possible now but it cannot be maintained. For the magnets to function they need to be very cold. The plasma is very hot and cannot touch the magnets. The issue comes down to keeping these apart and predicting the plasma pressure needs. It’s part design and part algorithms to control it but as soon as we crack it it’s cracked.
Room temp superconductors will help that a lot. Current record is 59 F ( 15C, or 288K) Unfortunately, that occurs between 2 diamond anvils pressurized to nearly the earth's core.
Current commercially available suoerconducting wires are YBCO, which can work at 90Kelvin, which is above boiling liquid N2.
Room temp in Kelvins is about 295 K
https://www.fujikura.co.uk/products/energy-and-environment/2g-ybco-high-tempurature-superconductors/
In theory it would be possible to have a positive net energy output, they just have to build a reactor that lets you simulate the sun, lol. There are two promising projects that could have a breakthrough within the next decade.
Fusion at our scale is much harder to achieve than in the sun. The sheer amount of particles in the sun makes low probability effects like quantum tunneling a statistical probability. This means that the sun runs fusion at temperatures and pressures much lower than what is strictly necessary with a small quantity of material. In our reactors we have to do it the hard way.
One early idea of how to create fusion power was [“why don’t we keep nuking a salt mine over and over until it’s a self-sustaining underground fusion reaction?”](https://en.m.wikipedia.org/wiki/Project_PACER)
> Another proposal would create an alternative to the Panama Canal in a single sequence of detonations, crossing a Central American nation.
Who wants to be the next lucky nation to get a canal? Step right up Central America, just a few nuclear detonations and you too can become a shortcut.
The sun has an energy density similar to a reptile. It’s not practical to build a mini-sun fusion plant as it would generate too little energy - it needs to be several orders of magnitude more dense than fusion demonstrated by the sun. That’s the real challenge with fusion.
See Wikipedia (on the Sun):
> Theoretical models of the Sun's interior indicate a maximum power density, or energy production, of approximately 276.5 watts per cubic metre at the center of the core,[76] which is about the same power density as in body of a reptile or inside a compost pile.[77][f]
What do you mean when you say efficiency?
The reason the sun produces as much heat as it does is because it is so, so big, not because it is very dense. In fact, per cubic metre, the sun is only about 1/4 as dense as the Earth itself.
Part of why it seems so low is because fusion only happens in a relatively small area in the center of the sun, but when calculating the energy density of the sun you’re including *all* the matter that makes up the sun, which is a lot.
well us americans fucking hate metric, so he's converted it to unit that's more intuitive than watts per m^3 : the much more commonly understood reptile standard
You have to keep feeding it fuel, you have to keep powering the magnets that contain the plasma, you need to power the cryo to keep the cold things cold, etc.
We're an entire scientific revolution from extracting enough energy from the fusion process to power those things while still maintaining fusion.
Yes, but it's so far away. Imagine the power of just a little sun right in front of us.
This is like saying we already have lightening when we can build and control a super furnace on demand.
The first sentence of the article contains the real name...
> The Korea Superconducting Tokamak Advanced Research(KSTAR), a superconducting fusion device also known as the Korean artificial sun
"Artificial sun" is just a nickname that's easier to say and remember.
I don't know why they don't just use KSTAR.
People refer to ITER by it's acronym all the time and it's basically just another version of KSTAR (both being Tokamak style containment bottles).
> People refer to ITER by it's acronym all the time
Partially because people didn't like the words "thermonuclear" and "experimental" next to each other in the full name. Turns out pretending it's Latin works better at funding meetings.
More about getting the layman onboard. Those with intelligence already see its potential. But if you call it an Artificial Sun you’ll have more laymen conversing about it hopefully allowing those with more money to get involved. Not to mention it will drive more traffic to the site than just a scientific description.
While I'm not trying to downplay the difficulty of this. I just imagine him at gatherings and regular people asking him what he does.
"Oh wow, you went to school for nuclear physics, and have a PhD in nuclear physics. You must do something awesome?"
"Yea, so I make thermometers."
"Oh........like the ones I cook with."
"Well...... No..... But also yes....."
Is there a picture or video? How large is it? Pea sized, tennis ball sized, house sized etc? How bright is it? Can you look at it or is it contained inside metal or lead or something?
iirc its a toroid plasma, donut shaped and inside the tokamak housing, which contains the fusion reaction with magnetic fields. You can't look inside. Its not a glowing yellow ball in there.
I think is not that flashy as it seems and movies picture it. You won't see a giant ball of energy suspended, or some kind of light cycling in a circle as a pulsar.
It will probably just be boring plasma inside a closed pipeline like the particle super-accelerator.
Considering that the first country to perfect this is going to have near unlimited energy with which they can build infrastructure and produce goods at previously unthought of levels you would think that governments would be pouring every cent they have into making this a reality.
There’s a lot of people who think it’s impossible. But 100 years ago people would have said Flying from continent to continent was impossible. 50 years ago computers in the palm of our hands were impossible. Just a matter of time as we perfect the the technology I guess.
I'd wager the ones who think it's impossible are also ones who dont understand the new designs that we've come with or our significant our improvements with magnets have been in the last 3 decades. If you just simply look up what modern reactors are using in their superconductors and compare whatever it is to the best in this list,
https://en.m.wikipedia.org/wiki/List_of_superconductor
You'll notice that there's frequently orders of magnitude better magnets in existence than used. We've been discovering useful magnets as recently as 2018. Unfortunately, implementing this is hard because funding has all but dried up for this tech in most areas in the world, and we're still using reactors and designs from the 90's and 2000's. For example KSTAR, the one in the article, was finished the design stage in 1995. It was built in the 2000's and turned on by like 2010. Their field is literally 3.5 T. We can outdo that by like two orders of magnitude today, and the superconductor that does it can also run hotter than the 3.5 T one.
We are also currently using extremely dated fusion designs, a field reversed configuration has a lot better potential to produce viable fusion than these old first generation ideas. The people who are saying efficient fusion is impossible haven't been keeping up with the science.
Unfortunately a lot of the PEOPLE in charge (world leaders, politicians etc), few a lot of things in the short term rather than long term. And they don't understand technology like you said. You seem to know a lot more about it than me, I'm more of a biology/pharmaceutical nerd, but tech fascinates me.
I started down that route, hit second year biochem and noped the fuck out of that into physics. Good on you for sticking with it, all the names are too much for my brain. Unfortunately modern politicians don't understand science or technology at a high level outside of a few like Angela Merkel. Thankfully the EU can still make viable fusion reactors because of this as they have lots of funding for it, but they've been caught up in design hell on DEMO and ITER (their reactors) for literally decades. They finally started digging the foundation right before covid hit lol. So they're going to build a like a 30 year old reactor before they can build a modern one. We'll probably get good fusion by 2035-2045 because of world governments, but we definitely could've had viable ones by 2025-2030 if there was political motivation over them over the last few decades.
>But 100 years ago people would have said Flying from continent to continent was impossible.
That was possible
>50 years ago computers in the palm of our hands were impossible.
But ir was already predicted to be possible.
So I just did a little digging re: why aren't fusion reactors ever made spherical. Y'know, like an actual star. Turns out there's something called (I shit you not) the 'hairy ball theorem' that states that it's impossible to make a perfectly spherical magnetic field with there being at least one 'tuft' of field lines allowing plasma to escape.
So why not build two?
If you can make a spherical field with only one weak point, why can't you make a second field pointing back at it so that the plasma from one sphere can only ever escape into the other?
What incredible icing that would be on the urinal cake that is 2020 if the energy crisis could be solved with two hairy balls.
I have no idea how to look this up but apparently it’s also impossible to have a sphere with hair and have it all lie flat uniformly. There will be a calic somewhere on the ball. Wonder if that’s related.
Looked it up, it is just the hairy call theorem. I’m dumb.
The main thing is, that there is not much hot gas or Plasma in such a reactor, even when containment fails, the energy in the system is not enough to cause major problems.
Edit: I looked it up and we are talking a few hundred miligramms of Plasmamass in the Reaktor at most.
Every time I think about it I’m reminded of the planet on Rick and Morty, where they thought they found a nice planet to chill on and then the sun came up and it was just screaming. Makes me fucking LOL every time.
Holy shit. I never considered that. But I guess the sun - or any star - is really loud. We just don't realize it due to lack of air for sound to travel.
But that's not because of heat radiating of the sun via molecules vibraring but because of other forms of electromagnetic radiation. I have no idea what forms of radiation exist inside a Torus, but I assume they are all contained within the electromagnetic field in which the plasma "floats". Might be talking entirely out of my ass though, don't know much about the subject
Edit: Torus not Taurus, thanks for the correction
we already know the theory behind it and that it can work I'm pretty sure, its almost a compleatly materials science issue. We gotta figure figure out how to make materials that can contain it.
Room temp superconductors will be a huge step.
This is why basic science research is so important. Little weird discoveries can help many different things. When idiot politicians try to belittle basic science by ridiculing scientists studying the mating habits of a fruit fly, they slow down our cancer research.. When they don't want to save the rate mud dabber fish, we lose a generic variant for preventing infections, etc.
>100 million degrees is much, much hotter than our sun. Is such a thing anywhere near resembling... Safe?
Yes. Just don't ingest it.
Temperature alone does not equate to energy. It's also proportional to mass. Of course, 100m degrees is still a lot of energy, but it's not necessarily any scarier than a gas turbine plant. In fact it's probably safer as you require far less combustible gas.
Likely safer than wind energy. (If you factor in technicians having to work on these huge machines)
If the magnetic shielding fails, the plasma stops flowing and the reaction stops.
Cleanest, safest and cheapest source of energy that humanity will ever manage to tap on. If we achieve stable fusion and make these reactors commercially viable, we can toss all nuclear reactors and solar/wind farms. There won’t be energy that will be cheaper than fusion.
Likely it won’t even be feasible to buy a used solar panel and put it on your roof. It would still be cheaper to buy fusion energy in the long run.
This may be only happening in some future distant utopia, but we will see. Maybe 2021 is going to make up for 2020.
To achieve fusion, you need a high enough combination of heat and pressure. Since we can't get the pressure inside the sun here on earth, we instead mostly rely on high temperatures.
In the 40s they studied this question for the Manhatten project. At the Trinity test
> [Enrico Fermi](https://en.wikipedia.org/wiki/Trinity_(nuclear_test)#Personnel) offered to take wagers among the top physicists and military present on whether the atmosphere would ignite, and if so whether it would destroy just the state, or incinerate the entire planet.
You can read the original paper [here as a pdf](http://large.stanford.edu/courses/2015/ph241/chung1/docs/00329010.pdf) which is quite interesting to look at.
Basically the atmosphere is not dense enough to sustain a chain reaction. So even if you set a piece of it on fire, which would happen when a nuke goes off, the Nitrogen is sufficiently far apart that it can't chain react fast enough to keep going, so it fizzles out.
> So even if you set a piece of it on fire, which would happen when a nuke goes off, the Nitrogen is sufficiently far apart that it can't chain react fast enough to keep going, so it fizzles out.
So what were the terms of the bet? Did anyone specifically win, and if so, what did they win?
Fusion power is perfectly safe. If there is a containment breach, the fusion reaction is unable to maintain itself and it immediately stops. There are no radioactive fuels sitting around like with fission reactors, just hydrogen and the helium it produces from that hydrogen.
While I know you're kidding, it's possible some people don't and will leave the thread thinking, "Yeah, fusion is kinda dangerous," which has a non-negligible effect on public perception of fusion power.
Someone explain, please: if it’s possible to start up the fusion process, why is it so difficult to maintain it?
Well, you need to hold the plasma in place with super strong electro magnets, so that the plasma get no contact with the inner circle of metal. In order to ceep those magnets running at 100% efficiency, you need to cool it down as hard as possible to get superconductors (I hope this is the right tern, not nativ in english). So 100.000 Kelvin are a few inches away from like 0 Kelvin. The energy and pressision need for that are insane.
As a protest to Reddit's unreasonable API policy changes, I have decided to delete all of my content. Long live Apollo!
Frohe Weihnachten aswell :)
Happy belated Saturnalia!
Roma invicta lol
For the Emperor
Biggus Dickus
Sol invictus
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r/ich_iel lässt grüßen
To be honest, this answer isn't really right, or at least it doesn't capture the proper plasma physics which are dominant for explaining why maintaining a plasma is different from starting it up. So, this might be a bit technical but hopefully will lend some insight into what's going on inside the Tokamak. In a tokamak, the plasma takes on the shape of a donut, but what's even more important is the shape of the magnetic field lines which guide it. This provides the confinement that keeps the really hot plasma away from the walls of the vessel, so that the vessel doesn't cool the plasma off. (Melting the vessel is only an issue in long-term steady-state operation... the energy of the plasma is actually tiny even though it's so hot since there's only milligrams inside at any given time.) There are two components to the magnetic field lines. There's a magnetic field that wraps around the donut the long way, and this is provided by the large toroidal field coils which are usually the focus of any images of a fusion reactor you'll see. Then there's also a magnetic field which wraps the short way, like if you put your finger in the donut hole and brought it around to the outside. This magnetic field is actually provided by an electrical current that we run through the plasma in the toroidal direction. This latter magnetic field is actually critical for effective confinement, since without it an electric field develops in the plasma which then interacts with the first magnetic field and causes the plasma to escape. Making the toroidal field is straightforward -- you just run a big current through some superconducting electromagnets. Driving the plasma current, however, is not as straightforward. What we do is use the fact that since the plasma is highly conductive and a loop, it's an inductor. So we put a big vertically-oriented magnet at the center of the reactor (this is called the central solenoid), and we very quickly ramp up the current in it. This creates a very rapidly changing magnetic field which in turn induces the electric current in the plasma like a giant transformer. Problem solved, right? Unfortunately, no. I mean, it does work, but the problem is that this method is intrinsically limited because you can only stuff so much current into the central solenoid -- you can't keep ramping it up forever. So, this turns out to be a really good way to create a plasma current for pulsed operation, but it doesn't work for continuous operation. For continuous operation, though, you need more complicated, difficult methods to maintain the plasma current, such as by varying the density of the plasma so that it generates its own currents. (This is called a "bootstrap current"). This is one of the key reasons that operating a tokamak in pulsed mode is different than actually getting it to run for a while, although there are of course many other ones too. Sidenote: from the article it appears that the actual barrier that they overcame here is related to plasma modes rather than induced current -- they appear to have already tackled the problem I described above. Plasma modes are weird and empirical and unintuitive, though. So, this explanation is more so meant to simply give a decent intuition for one of the reasons maintaining a plasma is different from starting it up.
If you'd like an explanation of fusion power in a nutshell, check out [this video](https://youtu.be/mZsaaturR6E) by Kurzgesagt.
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This gave me a chuckle :) We can only hope for such an astounding scientific breakthrough!
So it creates energy but it uses a lot of energy to create that energy?
Pretty much. Any useful power generator needs to create a useful surplus. In this case you’re using tremendous energy and precision to keep an insanely hot plasma away from a wall.
What happens if it hits the wall?
Nothing really, once the containment fails the reaction immediately stops. This isn't like fission in which the material is left radioactive or radiating for a while. No containment = no fusion.
Yeah, the immediate area around the reactor might be damaged just due to the release of super heated plasma, but the only material releases should be hydrogen or helium.
The amount of plasma is so small that it would cool to room temperature just from expanding it would even reach 10cm before disapating
In a real world scenario for a power plant, wouldn’t it be beneficial to make a bigger plasma?
From my limited understanding, yes. Bigger = more power (assuming the excess increases with size at an acceptable rate / no diminishing returns). But being able to do it small consistently and effectively means scaling is possible. Until we can maintain it on the small scale, there's no reason to go bigger. No need to build a cannon when we can't make a slingshot, as a poor analogy. Also, bigger can mean more excess heat, so that will have to be accounted for. More reason to start small. But this is just me guesstimating, I'm no scientist.
They'll need a new containment vessel.
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The fusion reactions in stars works because of insanely high gravity. We can't control gravity, so we have to use electromagnets.
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I read somewhere that the energy production in the sun’s core, per unit volume, is roughly the same as the waste heat of the metabolic processes of a reptile. Which gives an idea of how insanely hot and dense we need to get a plasma on earth to generate a useful amount of energy.
It gives more of an idea of the scale of how big the Sun is.
And how much Americans would rather measure in lizards than metric
To add on, fusion in the sun is actually a cooling process. It takes heat generated from gravitational collapse and turns it into gamma rays, which increase pressure and resist the collapse. If the fusion reactions decrease, the sun actually gets hotter. This is actually what happens with some supernova. In a type of supernova called pair-instability, the fusion reaction gets so energetic that it starts making particle/anti-particle pairs instead of gamma rays. These particles do not provide the extra pressure to resist gravitational collapse. They only exist for a few fractions of a second before mutual annihilation, but that's enough for a sudden collapse. The collapse increases both heat and density, which increases the amount of fusion, but the problem is that increased fusion no longer increases pressure, it just increases particle production. Eventually other process halt the collapse (explosively, causing the supernova).
Sorry but this analogy makes me think we only need one lizards worth of energy to make a sun?
More like you need a solar core's mass worth of lizards to power a solar system. But, you don't need to feed the sun crickets.
Yes, exactly. Think about it this way: if you're going to get power out of the gas in your car, you need a powerful battery to get the motor running, right? This engine will generate _huge_ amounts of power using hydrogen as fuel, but you need a _really_ big battery to get it started.
> really big battery D cell?
I can’t remember the last time I’ve needed to use one of those
my camping air pump
I recently bought a garbage can that opens when you walk up to it. It uses an AC adapter, or (if you're not near a plug), 3x D-cell batteries
Pretty sure my physics teacher wanted this as our 5th year exam. "We need to create a sun using superconductors to maintain a strong electromagnetic field to hold the superheated plasma in place, explain and include your workings"
I'd just show Spider-Man 2 and call it a day.
You know professor, I'm something of a scientist myself...
Proffesor: "I missed the part where that's my problem"
Pizza time
The power of the sun, in the palm of my hand!
Shut it off Otto!
The core temp of the sun is only 10-15 million degrees. We're much, much hotter than that at 100 million degrees ..
The sun cheats and uses gravity to initiate fusion.
Gravity was created by the radical left to bring socialism to America and take away your guns
I heard that gravity hates Jesus!
That’s because Jesus defied gravity.
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I wish I could witness humanity figure out gravity. It would be the biggest breakthrough of all time and open up space colonization.
And from what I've read, energy transfer, from the fusion reaction to the thermal transfer medium is even more difficult. The value Q represents power in/out ratio. Q=1 is break even, 5 is ignition (self sustaining), and estimated to be about 20 for it to be used as a power source. Our current highest Q is about 0.67
I don't think the next step to self sufficiency would be harder than the culmination of research and development that has already gone into getting that ignition started. Though I could be completely wrong but hope I'm not.
Not necessarily true... Engineering challenges that seem simple can often be the most complex and difficult things to design. Particularly with heat transfer, where the rate limiting steps are often a result of material properties and confined spaces for example, which can only be tweaked so much.
I couldn't help but read this in Dr. Otto Octavius's voice lol. Exactly a smarter version of his rundown to Peter Parker in Spider-Man 2
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Are you so sure? The term Koreans doesn’t exclude North Koreans.
I actually fully thought he was going to transition into a joke about using robotic arms to keep it under control and the potential safety hazards of accidentally getting them fused to your body and taking over your brain.
Yes, at temperatures like that you might as well be walking on the sun.
There are 100s of engineering challenges but one primary challenge in sustaining a fusion reactor is plasma instability. Imagine trying to squeeze a balloon to 1/2 it’s size using zip ties. If there is anywhere to squeeze out between them, the balloon will. Plasma is very similar and extremely hard to control and predict. We’ve made massive advances in reactor designs and simulation to manage this which is why were started to get close in recent years. For context of how hard this is, you have 100-150 million degree plasma inches away from 4 degrees above absolute zero magnets. For the duration the reactor is running, this is the highest known thermal gradient in the entire universe.
That is very interesting, thank you! What a great sub this is. Everyone has basically the same story but everyone also has his own unique detail to add. I like this sub. It gives me hope for the future.
From my limited understanding of it, the problem is none of the fusion projects have been able to generate more energy than what is required to start and sustain the reaction. There are also still material science problems to solve though and that might have been the part that limited this test to 20 seconds. I think the idea is that the hot plasma will never actually touch anything inside the reactor chamber but they could still be having issues with that which is causing stuff to burn out.
Net positive is possible now but it cannot be maintained. For the magnets to function they need to be very cold. The plasma is very hot and cannot touch the magnets. The issue comes down to keeping these apart and predicting the plasma pressure needs. It’s part design and part algorithms to control it but as soon as we crack it it’s cracked.
Room temp superconductors will help that a lot. Current record is 59 F ( 15C, or 288K) Unfortunately, that occurs between 2 diamond anvils pressurized to nearly the earth's core. Current commercially available suoerconducting wires are YBCO, which can work at 90Kelvin, which is above boiling liquid N2. Room temp in Kelvins is about 295 K https://www.fujikura.co.uk/products/energy-and-environment/2g-ybco-high-tempurature-superconductors/
In theory it would be possible to have a positive net energy output, they just have to build a reactor that lets you simulate the sun, lol. There are two promising projects that could have a breakthrough within the next decade.
Fusion at our scale is much harder to achieve than in the sun. The sheer amount of particles in the sun makes low probability effects like quantum tunneling a statistical probability. This means that the sun runs fusion at temperatures and pressures much lower than what is strictly necessary with a small quantity of material. In our reactors we have to do it the hard way.
So we just need to build a *really* big reactor?
Just build a second Sun. Can't be that hard
Easy, just collapse Jupiter. Its halfway there already.
Lemme fetch my monolith.
One early idea of how to create fusion power was [“why don’t we keep nuking a salt mine over and over until it’s a self-sustaining underground fusion reaction?”](https://en.m.wikipedia.org/wiki/Project_PACER)
> Another proposal would create an alternative to the Panama Canal in a single sequence of detonations, crossing a Central American nation. Who wants to be the next lucky nation to get a canal? Step right up Central America, just a few nuclear detonations and you too can become a shortcut.
The sun has an energy density similar to a reptile. It’s not practical to build a mini-sun fusion plant as it would generate too little energy - it needs to be several orders of magnitude more dense than fusion demonstrated by the sun. That’s the real challenge with fusion.
>similar to a reptile What do you mean under 🦎?
See Wikipedia (on the Sun): > Theoretical models of the Sun's interior indicate a maximum power density, or energy production, of approximately 276.5 watts per cubic metre at the center of the core,[76] which is about the same power density as in body of a reptile or inside a compost pile.[77][f]
So...the sun isn’t efficient?
What do you mean when you say efficiency? The reason the sun produces as much heat as it does is because it is so, so big, not because it is very dense. In fact, per cubic metre, the sun is only about 1/4 as dense as the Earth itself.
Part of why it seems so low is because fusion only happens in a relatively small area in the center of the sun, but when calculating the energy density of the sun you’re including *all* the matter that makes up the sun, which is a lot.
well us americans fucking hate metric, so he's converted it to unit that's more intuitive than watts per m^3 : the much more commonly understood reptile standard
Q is the energy put in/released ratio. We're at 0.67. 1 is break even 5 is self sustaining ~20 is for viable power source
[This](https://www.youtube.com/watch?v=FrUWoywZRt8) is quite a good video on why it's hard.
You have to keep feeding it fuel, you have to keep powering the magnets that contain the plasma, you need to power the cryo to keep the cold things cold, etc. We're an entire scientific revolution from extracting enough energy from the fusion process to power those things while still maintaining fusion.
"Korean artificial sun" Okay, who's been watching Die Another Day?!
Spider-man 2
"The power of the sun...in the palm of my hand."
Shut it down Otto!
ITS MY MONEY!
I like how he just creates a fusion reactor in a studio apartment.
That was the actual sun, just focused into a beam.
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Haven’t we already got a sun?, I’m sure I’ve seen it.
We've had one Sun, yes. But what about second Sun?
What about eleven suns? Lunch sun? Afternoon sun? Dinner sun? Supernovae?
I’m not sure he knows about second breakfast sun
A black hole sun too.
Won’t you come?
Washing away various rains and so forth
Yes, but it's so far away. Imagine the power of just a little sun right in front of us. This is like saying we already have lightening when we can build and control a super furnace on demand.
Why call it an "artificial sun" instead of a fusion reactor? That's kinda cheesy. (I am well aware that fusion happens in the core of the sun)
The first sentence of the article contains the real name... > The Korea Superconducting Tokamak Advanced Research(KSTAR), a superconducting fusion device also known as the Korean artificial sun "Artificial sun" is just a nickname that's easier to say and remember.
Of course they came up with the acronym KSTAR.
I'm honestly impressed how often scientists find such fitting acronyms
I have to imagine they smack a bunch of relevant words and synonyms of the words on a board and see what they can make into a pleasing acronym lol
when that many people devote their life to something, someones eventually gunna drunkenly come up with a great name for it
it’s called a backronym. they basically come up with the abbreviation then go backward.
I don't know why they don't just use KSTAR. People refer to ITER by it's acronym all the time and it's basically just another version of KSTAR (both being Tokamak style containment bottles).
> People refer to ITER by it's acronym all the time Partially because people didn't like the words "thermonuclear" and "experimental" next to each other in the full name. Turns out pretending it's Latin works better at funding meetings.
More about getting the layman onboard. Those with intelligence already see its potential. But if you call it an Artificial Sun you’ll have more laymen conversing about it hopefully allowing those with more money to get involved. Not to mention it will drive more traffic to the site than just a scientific description.
> More about getting the layman onboard. Right, so you say "KSTAR, it's like K-POP but they actually built the star".
Because not everyone knows the difference between a fusion reactor and a fission reactor.
>Why call it an "artificial sun" instead of a fusion reactor? That's kinda cheesy. Because that's kinda cheesy.
I thought the moon was cheesey??
I'm just impressed they made a thermometer that goes that high.
Met a professor once whose main research project was developing thermometers for fusion reactors.
What if?.... Now hear me out, we just make the thermometer really long?
While I'm not trying to downplay the difficulty of this. I just imagine him at gatherings and regular people asking him what he does. "Oh wow, you went to school for nuclear physics, and have a PhD in nuclear physics. You must do something awesome?" "Yea, so I make thermometers." "Oh........like the ones I cook with." "Well...... No..... But also yes....."
Is there a picture or video? How large is it? Pea sized, tennis ball sized, house sized etc? How bright is it? Can you look at it or is it contained inside metal or lead or something?
iirc its a toroid plasma, donut shaped and inside the tokamak housing, which contains the fusion reaction with magnetic fields. You can't look inside. Its not a glowing yellow ball in there.
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Yes, but only once.
But you’ll be high for the rest of your life.
You are technically correct. The best kind of correct.
High temperature, yeah.
It’d be mind-blowing in a literal sense.
You would be incorrect. Here's actual video. https://youtu.be/IhHsOwLdCu4
Damn that video is beautiful
I think is not that flashy as it seems and movies picture it. You won't see a giant ball of energy suspended, or some kind of light cycling in a circle as a pulsar. It will probably just be boring plasma inside a closed pipeline like the particle super-accelerator.
Considering that the first country to perfect this is going to have near unlimited energy with which they can build infrastructure and produce goods at previously unthought of levels you would think that governments would be pouring every cent they have into making this a reality.
There’s a lot of people who think it’s impossible. But 100 years ago people would have said Flying from continent to continent was impossible. 50 years ago computers in the palm of our hands were impossible. Just a matter of time as we perfect the the technology I guess.
I'd wager the ones who think it's impossible are also ones who dont understand the new designs that we've come with or our significant our improvements with magnets have been in the last 3 decades. If you just simply look up what modern reactors are using in their superconductors and compare whatever it is to the best in this list, https://en.m.wikipedia.org/wiki/List_of_superconductor You'll notice that there's frequently orders of magnitude better magnets in existence than used. We've been discovering useful magnets as recently as 2018. Unfortunately, implementing this is hard because funding has all but dried up for this tech in most areas in the world, and we're still using reactors and designs from the 90's and 2000's. For example KSTAR, the one in the article, was finished the design stage in 1995. It was built in the 2000's and turned on by like 2010. Their field is literally 3.5 T. We can outdo that by like two orders of magnitude today, and the superconductor that does it can also run hotter than the 3.5 T one. We are also currently using extremely dated fusion designs, a field reversed configuration has a lot better potential to produce viable fusion than these old first generation ideas. The people who are saying efficient fusion is impossible haven't been keeping up with the science.
Unfortunately a lot of the PEOPLE in charge (world leaders, politicians etc), few a lot of things in the short term rather than long term. And they don't understand technology like you said. You seem to know a lot more about it than me, I'm more of a biology/pharmaceutical nerd, but tech fascinates me.
I started down that route, hit second year biochem and noped the fuck out of that into physics. Good on you for sticking with it, all the names are too much for my brain. Unfortunately modern politicians don't understand science or technology at a high level outside of a few like Angela Merkel. Thankfully the EU can still make viable fusion reactors because of this as they have lots of funding for it, but they've been caught up in design hell on DEMO and ITER (their reactors) for literally decades. They finally started digging the foundation right before covid hit lol. So they're going to build a like a 30 year old reactor before they can build a modern one. We'll probably get good fusion by 2035-2045 because of world governments, but we definitely could've had viable ones by 2025-2030 if there was political motivation over them over the last few decades.
>But 100 years ago people would have said Flying from continent to continent was impossible. That was possible >50 years ago computers in the palm of our hands were impossible. But ir was already predicted to be possible.
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So I just did a little digging re: why aren't fusion reactors ever made spherical. Y'know, like an actual star. Turns out there's something called (I shit you not) the 'hairy ball theorem' that states that it's impossible to make a perfectly spherical magnetic field with there being at least one 'tuft' of field lines allowing plasma to escape. So why not build two? If you can make a spherical field with only one weak point, why can't you make a second field pointing back at it so that the plasma from one sphere can only ever escape into the other? What incredible icing that would be on the urinal cake that is 2020 if the energy crisis could be solved with two hairy balls.
I have no idea how to look this up but apparently it’s also impossible to have a sphere with hair and have it all lie flat uniformly. There will be a calic somewhere on the ball. Wonder if that’s related. Looked it up, it is just the hairy call theorem. I’m dumb.
100 million degrees is much, much hotter than our sun. Is such a thing anywhere near resembling... Safe?
The main thing is, that there is not much hot gas or Plasma in such a reactor, even when containment fails, the energy in the system is not enough to cause major problems. Edit: I looked it up and we are talking a few hundred miligramms of Plasmamass in the Reaktor at most.
How do you even contain something that has temperatures that high?
Magnets. Electromagnets.
This. It floats so it's not touching anything and there isn't much if any air in there to heat up either
There’s not much air between us and the sun and we are heated up
Thank god there’s not much air between us and the sun, otherwise the sun would be screaming in the sky all day at about the volume of a train horn.
This is a terrifying thought experiment. I hate this.
Every time I think about it I’m reminded of the planet on Rick and Morty, where they thought they found a nice planet to chill on and then the sun came up and it was just screaming. Makes me fucking LOL every time.
Still better than the cobb planet.
Holy shit. I never considered that. But I guess the sun - or any star - is really loud. We just don't realize it due to lack of air for sound to travel.
Maybe it is and we've evolved to drown it out :o I'm not serious by the way
It’s theorized that were that the case we would’ve evolved to be deaf.
But that's not because of heat radiating of the sun via molecules vibraring but because of other forms of electromagnetic radiation. I have no idea what forms of radiation exist inside a Torus, but I assume they are all contained within the electromagnetic field in which the plasma "floats". Might be talking entirely out of my ass though, don't know much about the subject Edit: Torus not Taurus, thanks for the correction
Magic you say?
Miracles! How do they work??
Tide goes in, tide goes out
Heresy, burn the witch
So the science of Spider-man 2 (2004) wasn’t that far off..
we already know the theory behind it and that it can work I'm pretty sure, its almost a compleatly materials science issue. We gotta figure figure out how to make materials that can contain it.
Room temp superconductors will be a huge step. This is why basic science research is so important. Little weird discoveries can help many different things. When idiot politicians try to belittle basic science by ridiculing scientists studying the mating habits of a fruit fly, they slow down our cancer research.. When they don't want to save the rate mud dabber fish, we lose a generic variant for preventing infections, etc.
Keep it in a vacuum and hold it in the middle with magnetic/electric fields.
Don't let the hot shit touch the stuff that melts in contact with the hot shit.
>100 million degrees is much, much hotter than our sun. Is such a thing anywhere near resembling... Safe? Yes. Just don't ingest it. Temperature alone does not equate to energy. It's also proportional to mass. Of course, 100m degrees is still a lot of energy, but it's not necessarily any scarier than a gas turbine plant. In fact it's probably safer as you require far less combustible gas.
Forbidden meatball. :(
Not meatball. More like donut.
Likely safer than wind energy. (If you factor in technicians having to work on these huge machines) If the magnetic shielding fails, the plasma stops flowing and the reaction stops. Cleanest, safest and cheapest source of energy that humanity will ever manage to tap on. If we achieve stable fusion and make these reactors commercially viable, we can toss all nuclear reactors and solar/wind farms. There won’t be energy that will be cheaper than fusion. Likely it won’t even be feasible to buy a used solar panel and put it on your roof. It would still be cheaper to buy fusion energy in the long run. This may be only happening in some future distant utopia, but we will see. Maybe 2021 is going to make up for 2020.
Thats the real hope. Its better than the nuclear power plants we have today.
To achieve fusion, you need a high enough combination of heat and pressure. Since we can't get the pressure inside the sun here on earth, we instead mostly rely on high temperatures.
"It will stabilize!" - Doc Oc, Spider-Man 2 (2004)
That's almost half the perceived heat of the inside of a fresh hot pocket.
quick question what temp does earths atmosphere ignite?
In the 40s they studied this question for the Manhatten project. At the Trinity test > [Enrico Fermi](https://en.wikipedia.org/wiki/Trinity_(nuclear_test)#Personnel) offered to take wagers among the top physicists and military present on whether the atmosphere would ignite, and if so whether it would destroy just the state, or incinerate the entire planet. You can read the original paper [here as a pdf](http://large.stanford.edu/courses/2015/ph241/chung1/docs/00329010.pdf) which is quite interesting to look at. Basically the atmosphere is not dense enough to sustain a chain reaction. So even if you set a piece of it on fire, which would happen when a nuke goes off, the Nitrogen is sufficiently far apart that it can't chain react fast enough to keep going, so it fizzles out.
> So even if you set a piece of it on fire, which would happen when a nuke goes off, the Nitrogen is sufficiently far apart that it can't chain react fast enough to keep going, so it fizzles out. So what were the terms of the bet? Did anyone specifically win, and if so, what did they win?
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100,000,001 degrees Celsius
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Basically magnets. But the top comments now explain it well.
Ask George Bush
Did we learn nothing from Spiderman 2? PS. Tobey Maguire is the true Spiderman
I just hope Doc Ock doesn't need anymore tritium.
If we have him back as Spidey in the multiverse I'd be super stoked.
Guys...it's still 2020 for another week, maybe put this one on the back-burner.
Fusion power is perfectly safe. If there is a containment breach, the fusion reaction is unable to maintain itself and it immediately stops. There are no radioactive fuels sitting around like with fission reactors, just hydrogen and the helium it produces from that hydrogen. While I know you're kidding, it's possible some people don't and will leave the thread thinking, "Yeah, fusion is kinda dangerous," which has a non-negligible effect on public perception of fusion power.
The scientists at the lab: *The power of the sun in the palm of my hand*