Chinese Fusion Reactor Maintains 70 Million Degrees Celsius For More Than 17 Minutes (heise.de) 117
spth writes from a report via German publisher Heise: The Experimental Advanced Superconducting Tokamak (EAST) in Hefei, China has maintained a temperature of 70 million degrees celsius for 17 minutes at the end of 2021. It had previously held 120 million degrees celsius for 101 seconds and 160 million degrees celsius for 20 seconds. The goal is to keep 100 million degrees for one week. The purpose of the research at EAST is to support the International Thermonuclear Experimental Reactor (ITER) in Cadarache, France. The reactor maintained these temperatures for exactly 1,056 seconds, or 17 minutes, 36 seconds, notes the Institute of Plasma Physics Chinese Academy of Sciences in an announcement.
20 years (Score:1, Funny)
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Where does that number come from?
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the articles about fusion energy from the 1950s on.
Apparently none of the people actually working on Fusion, or who really understands the physics and technology involved, have ever said on record when it would be ready. It's always been the journalists and the Public relations people claiming that time frame.
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Well, they haven't said when it would be ready, but they have made predictions. Naturally those predictions are contingent on how big a priority the research program is; basically, the amount of funding.
We're rather ahead of the 1970s predictions.
https://www.reddit.com/r/Futur... [reddit.com]
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basically, the amount of funding.
If the funding had been more generous back in the 1950s, it would have been wasted because other technologies needed, such as high-temperature superconductors and fast microprocessors, didn't exist.
The Hefei reactor is cooled with liquid helium and doesn't use high-temperature superconductors, but a commercial reactor won't be cost-effective with liquid helium cooling.
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Yes. We hadn't been given those inventions by our patrons yet. They're very strict at only giving humanity a set number of presents on each of our birthdays.
Re:20 years (Score:5, Insightful)
Bad jokes from the ignorant or indifferent, I'm guessing.
The background:
Back when we first started getting serious about sustainable fusion research the researchers looked at how much work needed to be done, and how much funding they were getting per year with which to do that work, and estimated it would take about 20 years to complete.
Sadly, while progress per dollar has actually tracked remarkably well with those initial estimates, funding has not. Rather than receiving the same amount every year for twenty years, as the estimates had assumed, funding levels have been reduced almost every year, severely enough that all these decades later we're *still* 20 years away from delivering the total "20-year" funding initially promised. And not surprisingly, when you reduce the funding for expensive research, the pace of research diminishes in step, so estimates of when we'll have the first viable fusion reactor have also remained perpetually 20 years in the future.
Along the way the funding details have tended to get overlooked by the masses, and it has become a running joke that fusion is forever 20 years away - with the implication being that the problem is far more challenging than initially estimated. Basically trying to blame the researchers for being overly optimistic about the project difficulty, rather than laying the blame where it belongs, firmly at the feet of duplicitous politicians more interested in funding fossil fuel subsidies and military boondoggles.
On the bright side, the perpetual frustration at the lack of funding has promoted a lot of research into a wide range of wildly different and potentially much cheaper fusion technologies by various smaller groups, with Lockheed Martin backing one of the newer ones. A few of which promise to be far superior to tokamaks for conveniently sized commercial reactors, if they can get them working.
On the darker side - even if we had a fully functional experimental reactor today, there's still likely to be loads of practical problems to solve to make a mature commercial reactor - for example fusion produces FAR higher levels of neutron radiation per watt than fission, as well as operating at far higher temperatures, presenting major material science challenges for the reactor chamber. Then there's the bureaucratic roadblocks - licensing, dealing with NIMBY lawsuits, etc. As I recall it currently takes (in the US) about 15-20 years between deciding to build a boring old-school fission reactor (or even a hydroelectric dam) and when the first electricity is delivered to the grid. So basically, fusion isn't a realistic candidate to solve global warming - by the time we could reasonably expect the first reactor to become operational, it'd already be far too late. It is however a very promising long-term candidate to solve the problems with whatever technologies solve the global warming problem - e.g. we could build tons of fission reactors today, and when they're decommissioned in 50-100 years we replace them with fusion reactors that don't produce such an outrageous stream of long-lived radioactive waste.
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The drop in funding can't totally excuse this slippery timeframe that has been reported ever since I first heard about Fusion 40 years ago when I was a kid reading articles about this.
From 1958 to 1975 funding remained relatively constant in inflation adjusted dollars at about 200M
It peaked sharply in 1977 at 1.3B dollars then gradually dropped to 400M in 1996 ahd has remained relatively stable at that level ever since. http://large.stanford.edu/cour... [stanford.edu]
I think it's more a lack of really knowing how long it
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Well, yes it can.
First, you can't build the kind of reactor needed, and the computer needed to control it, for $400m.
Second, that $400m would have been fine if the US was still involved in international projects. It pulled out and decided to go it alone. This increased costs by seveal orders of magnitude.
Third, the US isn't trying one approach but is trying many. So the slice of the pie that goes to each approach is falling.
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Fusion and specific extremely expensive prototype needs aside this is the problem with predictions like this.
In short term instances you can make reasonable guesses but when you are talking about something a decade out... you might as well be asking for a fictional work. No amount of expertise about what we do know tells you what we don't know o
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Then there's the bureaucratic roadblocks - licensing, dealing with NIMBY lawsuits, etc. As I recall it currently takes (in the US) about 15-20 years between deciding to build a boring old-school fission reactor (or even a hydroelectric dam) and when the first electricity is delivered to the grid.
Well, some people think fission reactors are dangerous, and when they do go wrong they can be rather expensive to clean up.
and dams can be insanely dangerous [wikipedia.org].
Fusion reactors should be way safer than either of those.
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But this is China we're talking about. A government studded with engineers, not lawyers. NIMBYs and anti-science folk have no political power. There is funding for all potential sources of energy. Fusion isn't here yet, but it's closer than ever, and advanced fission designs are about to roll out of Chinese factories while we're still dithering.
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Why in the world would you think China, of all places, is some technocratic utopia run by engineers? It's a state-capitalist authoritarian dictatorship. Engineers who say the wrong things or challenge China's rich and powerful get their organs harvested.
If any advanced fission designs roll out of Chinese factories, they will be designs created in the west and merely stolen by the Chinese. Educate yourself: https://en.wikipedia.org/wiki/... [wikipedia.org]
The only thing China is any good at is propaganda. Given all the obvi
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We may have thought of thorium fuel (4x more plentiful than uranium) and molten salt coolant to allow fission reactors to run at a sufficiently high temperature that they can use desert air as a heat sink, rather than oceans and rivers, but it's China that is actually testing both these designs:
https://www.nature.com/article... [nature.com]
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Second sentence of the article contradicts your claim that these technologies have not been tested before: "Although this radioactive element has been trialled in reactors before, experts say that China is the first to have a shot at commercializing the technology."
Experts? You mean, Chinese propaganda agents? Everyone has "a shot" at commercializing this.
And since when do communist countries "commercialize" things?
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We tested thorium at ORNL, and a reactor ran for twenty years. But it didn't interest the Pentagon, so we didn't bother producing a commercial version of it.
And while China's government is Communist and runs a dictatorship that suppresses free speech and builds concentration camps, its economy is capitalist. That's exactly why the Chinese economy is so strong.
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Color me confused, isn't communism an economic theory? How can a political party be communist but run a capitalist economy? What makes them "communist" besides the fact that they say so?
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The Chinese government is a totalitarian dictatorship, at that point where the ends of the political spectrum, bent into a circle, come together.
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>What makes them "communist" besides the fact that they say so?
Absolutely nothing. Just like every other "communist" regime in modern history.
Sadly, the number of people in the world that care about accurately labeling economic systems is apparently vastly outweighed by politicians and other blow-hards, eager to use "communism" as an empty buzzword to endorse or condemn their topic du-jour, along with armies of followers willing to take them at their word without knowing or questioning the actual defini
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That makes no sense. Either you are for worker control of the means of production, or you aren't. If you don't think the people who work should control their workplace and work life, you simply aren't a communist.
Lots of places say they are something they are not. And authoritarians response to communism is always to co-opt the language, while stoking anger at some perceived "other." It is this other: a foreigner, a gay, an intellectual, who is the enemy. Not the oligarchs running society. Look at history,
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Just give me a stateless society without currency and with democratic control of the means of production. Use rights not property rights. Telecommunications have made the price signal irrelevant, project CyberSyn in Chile showed that even in 1970, we had the technology to link customers, factories, and government together (Chile was socialist, not even claiming to be communist, under Allende. So still a state.)
And then keep the CIA killers away, thanks.
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17 minutes is a hell of a long time (Score:3, Informative)
In before the short sighted fools claiming fusion is always 50 years away. How about 17 minutes then, you jackballs. For a research reactor, that has to accommodate all kinds of instrumentation instead of a cooling system that is pretty good. If 17 minutes is possible then one week should be possible too with some modifications. This is good news for ITER and DEMO. If ITER demonstrations scientific breakeven, it means the tokamak scaling equations work and DEMO should be viable to prove economic profitability.
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Re: 17 minutes is a hell of a long time (Score:2)
Thankfully, if you look up MITâ(TM)s SPARC/ARC reactors (which theyâ(TM)ve just spun off Commonwealth Fusion Systems to build), youâ(TM)ll see that thereâ(TM)s a pretty good chance that high temperature superconductors can solve that problem.
Re: 17 minutes is a hell of a long time (Score:5, Funny)
We'll have viable commercial fusion before /. supports Unicode.
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Not 50 years, but sustaining fusion for a week should be possible within 20 years. :)
But seriously and joking aside, sustaining a temp of 70 million degrees for 17 minutes is quite an incredible accomplishment.
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But seriously and joking aside, sustaining a temp of 70 million degrees for 17 minutes is quite an incredible accomplishment.
It sure is impressive. But how does it, or 100m degrees for a week, actually translate to being able to extract energy from this?
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Path some of the heat to heat exchanger, heat water to pressurised steam, drive steam through a steam turbine connected to a generator that is synced to a grid. This part of the technology is actually tried and true except for primary heat exchanger that could channel heat from those temperatures.
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That is a problem with the process of fission without the massive gravity well of a star so far. We're forced to pump energy into the process to keep it going rather than have it become spontaneous and net energy producing. At least at this stage.
It has nothing to do with methods we use to transition heat into power.
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Impressive but you do realize that fusion power plants will still be decades away, 30 years from now would be rapid, so 50 years might indeed be the reality. This experiment is in support of ITER, which itself won't be a power plant but has a 20 year roadmap to 2035 to test in integrated way the subsystems of a fusion plant.
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The great thing about this is that it's a really international effort, including China. Working together we can do this.
We should do the same in space, and on everything else where we can cooperate.
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We can cooperate on genociding Uighurs, Mongols and Tibetans. Easily.
Should we?
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JFK wanted to cooperate with the Soviets for a moon mission back in the 1960s, even as the two countries had fingers hovering over the nuclear button. Plenty of bad stuff going on in the USSR. There was a bigger picture back then, as there is now.
Meanwhile Musk just opened a showroom in Xinjiang. Intel apologised for criticising the region. I'd say it's much better to cooperate on science and boycott economically.
https://www.theguardian.com/wo... [theguardian.com]
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But why? Because we were attacked and defended ourselves? Nope. It is because we recognize the evils of the Nazi's, their totalitarian socialist regime and their crimes against humanity to the extent that for many 'ki
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Is this a real development, or just using tritium? (Score:1)
Tokamak reactors have been around for ages. Everyone knows that if you use them with tritium, they get a lot more reactions out of them. Downside is that the entire tokamak structure has been rendered radioactive, and dangerous. Anyone know if this is an actual advance, or if someone just hooked up a N2O tank to a 1980s Lada engine to get 500-1000 horsepower... until rods get thrown.
Big Deal (Score:1)
70 million Celsius for 17 minutes ????
The Coma Cluster of galaxies is filled with gas at a temperature of 100 milliion K (not those whimpy Celsius degrees) and has been in that state for billions of years.
https://ned.ipac.caltech.edu/l... [caltech.edu]
Move along, nothing to see ...
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The difference between 100 million K and 100 million C is relatively so small it's an irrelevant rounding error. If you'd mentioned the obsolete Fahrenheit scale instead of Celsius, it would be a different story.
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But the same caltech document states that the intracluster gas in the Coma cluster has an "atomic density of approx 1/1000 per cm3" which is incredibly small. For comparison, the density at 1atm is 2.50x10^19 per cm while it is 4x10^5 on the Moon.
An object placed in such a vacuum at 100 MK would not become hot because it would lose more energy by its own black body radiations than it would gain from collisions with the surrounding (and almost non existent) gas molecules.
The article does not specify the dens
Sounds pretty impressive (Score:3)
Re: Sounds pretty impressive (Score:2)
Look up Commonwealth Fusion Systems. MITâ(TM)s been working with high temperature superconductors, and appears to have managed to solve a lot of the problems surrounding current reactors. Theyâ(TM)re saying they think they can have a reactor called SPARC with a Q_plasma above 1 (around 5 in fact) up and running within 5 years, and then a somewhat larger reactor with a Q_total greater than 1 within another 5 years after that.
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ITER is planning to be running with deuterium by 2035. I think that by the time it is commercialized I'll be pretty old, even if everything goes according to plan. It's a shame because we need solutions now.
By the time it's ready I do wonder how much demand for it there will be, as I'd expect most energy to be renewable and very cheap by then. That will make it harder to commercialize fusion, but it will probably happen for some specific new industries that need very large amounts of energy. To my mind the
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We already have solutions. Fission works fine, hydro works fine. Easily last us hundreds of years if not thousands if we actually went all in.
But they don't bring the glorious leftist revolution to the evil capitalist way of life and instead enable it to continue and improve, "stabilizing the working class" to use the Maxist lingvo you are so fond of, so they're obviously not acceptable to people like yourself. As exemplified by Greens in Germany today, where they're having a small meltdown within the gover
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Fission definitely does not work fine. It's not affordable either, and that has nothing to do with "leftists" or lawsuits or anything like that.
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"We're making it cost exorbitant amounts of money through various legal sanctions, so it's clearly too expensive!"
I know that being a far left nutjob, you firmly believe that by altering language, you can alter reality. But that still doesn't mean that your horrific actions toward someone or something make that someone or something horrid.
It just means that you are a horrid human being.
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Look at the plants being built in Europe. Minimal legal hassles, still insanely expensive.
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Hmm...how will electricity be created from fusion? (Score:5, Interesting)
Will it be the same way as with fission-heat water, turn it into steam, and then use the steam to run turbines?
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Re:Hmm...how will electricity be created from fusi (Score:5, Interesting)
The helium nucleus carries an electric charge which will be subject to the magnetic fields of the tokamak and remain confined within the plasma, contributing to its continued heating. However, approximately 80 percent of the energy produced is carried away from the plasma by the neutron which has no electrical charge and is therefore unaffected by magnetic fields. The neutrons will be absorbed by the surrounding walls of the tokamak, where their kinetic energy will be transferred to the walls as heat.
In ITER, this heat will be captured by cooling water circulating in the vessel walls and eventually dispersed through cooling towers. In the type of fusion power plant envisaged for the second half of this century, the heat will be used to produce steam and by way of turbines and alternators electricity.
In terms of sheer scale, the energy potential of the fusion reaction is superior to all other energy sources that we know on Earth. Fusing atoms together in a controlled way releases nearly four million times more energy than a chemical reaction such as the burning of coal, oil or gas and four times more than nuclear fission.
from https://www.iter.org/sci/Makin... [iter.org]
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Frankly I'm getting tired of the heat transfer through coolant to generator.
It feels like the equivalent of leveraging an object with a long stick on a pivot point when people are using superconductors to levitate a magnet.
Where is the cooler but much more complex successor to electricity creation?
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I'm right there with you, I need something much more compact for my Terminator T1000 style power supply. Ideally the fusion products would be high energy charged particles that could transfer energy directly to an electrostatic field. This is theoretically possible when you use Helium-3 as a fuel. I'll leave it up to the reader to research Helium-3 fusion power. However this tech is probably what comes after the current generation
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Why do you want a complex solution to an industrial problem where a simple, efficient and functional solution exists?
That is number one the enemy of good engineering.
Re:Hmm...how will electricity be created from fusi (Score:4, Interesting)
I'm pretty sure that's per mass of reactant. So while fusion may yield 4x as much energy per mass than fission, because your reactants are super-light hydrogen (about 11 grams per liter at STP) vs super-dense uranium (about 19 kg per liter, or over a thousand times denser), the volumetric energy density of fission is still a lot higher than for fusion.
Some quick searching says EAST generates about 7.5 MW thermal, with the highest power output tokomak thus far being JET in England at 16 MW. ITER's target is 500 MW thermal for a few minutes at a time. For comparison, a large fission reactor generates 3-4 GW of thermal power continuously. So we are still very much in the baby steps stage of fusion. (The volumetric energy generation (W/m^3) by fusion inside the sun's core is even worse. It's about the same as a compost heap [wikipedia.org] - a bit less than 300 Watts/m^3. Yup, that pile of dead leaves in your backyard generates as much heat per volume as the sun's core.
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Basically, at least on earth. Outside of earth there are many ways - you have photosynthesis, solar power, solar heating (wind, hydro, etc).
Everything ends at iron. For elements lighter than iron, fusion produces energy. For elements heavier than iron, fission produces energy. Once your each iron, you're stuck.
Stars produce heavier elements because they are extremely dense, so gravity keeps fusing
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"gravity keeps fusing the heavier elements"
I'm 99% sure elements heavier that iron are not made by gravity, but by neutron stars going boom.
Per https://www.science.org/conten... [science.org]:
Some of the heavier elements in the periodic table are created when pairs of neutron stars collide cataclysmically and explode, researchers have shown for the first time. Light elements like hydrogen and helium formed during the big bang, and those up to iron are made by fusion in the cores
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Yes, because there are no more efficient ways to convert heat to electricity at scale that we know of that is cost effective.
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What happened after 17 minutes? (Score:5, Interesting)
Having trouble with the German translation so I'll just ask it - what happened at 17 minutes that required them to stop?
This isn't a criticism in any way, I'm just wondering what it is that requires them to shut it down. What would have happened if they went for 18 minutes?
(...really hoping the explanation involves the word "portal"...)
Re:What happened after 17 minutes? (Score:5, Informative)
Fusion reactions in this kind of reactor occur in a stream. I'm unsure about this specific case, but one common problem seems to be something called "the sausage instability", where the plasma pinches. https://en.wikipedia.org/wiki/... [wikipedia.org]
In order to avoid the instability of the plasma, you need extremely good sensors and very, very fast, computers capable of digesting the masses of information and adjusting the magnetic fields at every point at high speed in real time.
What was the pressure and tripple product (Score:3)
This lets you know how close you are to break-even. A paper at https://ui.adsabs.harvard.edu/... [harvard.edu]
seems to say the triple product was 1e19 m^-3 KeV-S That isn't bad but the Japanese JT-60 reports 100X higher 1.5e21 https://en.wikipedia.org/wiki/... [wikipedia.org]
Unless there is some difference in units (quite possible) the Chinese EAST project seems OK but not yet at state of the art. But if someone knows that the units are somehow different, or the abstract a mistake, I'd be interested in knowing
Re:What was the pressure and tripple product (Score:5, Informative)
EAST is a member of the ITER collaboration. It's a test reactor designed to test specific things, the big one being how to keep the plasma stable.
It's not supposed to edge closer to breakeven, it's supposed to discover specific techniques that, when combined with those from other research programs, will help ITER to do so.
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How far back... (Score:2)
Glorified steam engines and a propaganda moment (Score:1)
Whoopdedo! I'm so impressed... (Score:2)
Call me when they reach 20 minutes in 2050.
Re:Question (Score:5, Insightful)
I don't study stellar nucleosynthesis, but I believe it has something to do with the huge mass of gravity involved, creating pressure.
Re:Question (Score:5, Insightful)
The pressure makes a big difference. Because we don't have the pressure, a tokamak has to be much hotter than the core of the sun. The sun's core is at about 15M K. Tokamaks need to be at 100M K, and that is for DT fusion which is much easier than the P-P fusion used by the sun.
Solar trivia: Per unit volume, the sun produces less energy than a backyard compost bin.
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How is it we have so much difficulty trying to create a fusion reaction, yet the hydrogen atoms in the universe don't seem to have much problem coalescing into stars and starting their own fusion reactions?
It just seems odd how quadrillions of atoms can miraculously come from all over to a single point and get things rolling on their own.
Three reasons: time, gravity, and sheer number of hydrogen atoms.
Like the proverbial butterfly's wing-flap leading to a hurricane, any inhomogeneity in the distribution of the universe's hydrogen atoms can, given time, lead to clumping that forms stars. There's more involved of course, but that's pretty much the basics of it.
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There's a fourth, symmetry. In a fusion reactor, the hydrogen is placed in a stream that has a habit of pinching, requiring extremely rapid, delicate control to prevent. A star doesn't have this problem because it's a sphere and not a stream.
Re: Question (Score:4, Funny)
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Because we lack the ability to create something with the mass of a star on Earth under lab conditions.
Gravity might be a weak force, but quantity on an astronomical scale rapidly makes it a force to be reckoned with. The quantity of hydrogen we can get together in one place is a mere speck compared with the brute force approach that causes stars.
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Still, for fusion you want enough temperature ~few X 100M degrees and enough pressure and time. The sun provides fantastic pressure and lots of time.
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Gravity. We can't warp space and time to create the requisite gravity well to create the huge pressures and temperatures to fuse hydrogen atoms. That would take something with some multiples the mass of Jupiter to spark auto-ignition in the core of that mass, at the bottom of that gravity well.
Perhaps there is another easy, elegant way to fuse hydrogen nucleii. [energy.gov] There was that buzz about the Pons and Fleischmann cold fusion possibility in 1989, which turned out to be false. Perhaps some way yet unguessed. Ho
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Because the pressure at the sun's core is a one million gazillion times higher than here on earth. In fact the sun's core is so dense it blocks the light from leaving and it takes a photon a million years to finally reach the surface, then another 7 minutes to reach earth. That's right, the light you see tomorrow will have began it's journey one million years ago (plus 7 minutes :)
With that kind of pressure the sun's core only needs to be 25 million degrees in order to fuse H. We can't create sustainabl
Re:Question (Score:4, Funny)
How is it we have so much difficulty trying to create a fusion reaction, yet the hydrogen atoms in the universe don't seem to have much problem coalescing into stars and starting their own fusion reactions?
Put a quantity of hydrogen several times the mass of Jupiter in a thermos and get back to me ...
It just seems odd how quadrillions of atoms can miraculously come from all over to a single point and get things rolling on their own.
You call it "miraculous", the rest of us call it gravity and millions of years.
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When you've always lived in the desert, seeing an ocean for the first time would seem magical and like a miracle as well.
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Still a miracle. Understanding how the magic works does not always make it less magical.
Indeed. Just try explaining why the magic works. Physics is the way it is because.... magic?? God?? just because??
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Re: Question (Score:3)
Because we don't have the benefit of a literal sun's worth of mass to compress the atoms together for us?
And we can create fusion reactions no problem, the issue is containing them in a useful, non-destructive way. If you want to level a city, that fusion technology exists. If you want to power that city cleanly, we have a lot of work to do to contain and harness the reaction.
Fusion is easy (Score:5, Insightful)
>How is it we have so much difficulty trying to create a fusion reaction, yet the hydrogen atoms in the universe don't seem to have much problem coalescing into stars and starting their own fusion reactions?
Actually, fusion is easy. We've been creating fusion reactions for decades, and any sufficiently clever teenager can build a Farnsworth Fusor in their basement with a couple hundred bucks of second-hand equipment. And the cleverness is really only needed to avoid electrocution and dosing anyone with dangerous levels of neutron radiation - the reactor is just a couple of concentric spherical wire electrodes in a vacuum chamber.
What's hard, is *break even* fusion - fusion that releases more energy than was consumed to cause the reaction. Farnsworth Fusors got a lot of attention for many years because they are so easy to build, and so theoretically elegant: It takes a lot of energy to slam two atoms into each other fast enough to enable fusion to occur, and in a Fusor the collision happens at the bottom of a deep electrostatic potential well, so if the atoms bounce off each other rather than fusing (which is what usually happens) they simply race up the sides of the well before falling back in to collide again, with no loss of energy. Sadly the atoms will occasionally collide with the inner electrode rather than flying out and falling back in, and their energy is lost as heat. And despite many attempts at clever designs, nobody ever managed to get them past about 80% of break-even - though they did serve as the starting point for Dr. Bussard's Polywell reactor, which judging by the last NAVY progress report published was showing very promising results before funding ran out and the team took their research private several years ago.
Anyway - point is, fusion is easy - it's making more energy than you put in that's hard.
And for the sun - well, you have around 95% of the entire mass of the solar system crammed into a tiny ball (hopefully that part doesn't confuse you - gravity + "air resistance" makes a cloud condense into a star, and the planets formed similarly from the scraps that were left over.) That creates a massively deep gravitational potential well accelerating atoms toward the center. Not entirely unlike the Farnsworth fusor's electrostatic well, but deeper, and with no inner electrode for atoms to collide with and lose energy.
And It's actually even a lot better than that - the sun's core is incredibly dense, about 14x denser than lead. You pack hydrogen that closely together and you've got near-continuous collisions at fusion-enabling speeds.
But even with all that, it's *still* really rare for hydrogen atoms to fuse. The sun actually has an incredibly low power density - the core only produces about 573microwatts per kg [1] - your body actually produces about 2000x more energy per kg than the sun's core. It's just that the sun is so insanely huge that it's total output wins by a landslide.
So, for a useful fusion reactor we actually need to build something with a radically higher energy density than the sun itself. Not really so surprising that it's so much more difficult than just letting a big hydrogen cloud condense under its own gravity.
[1]
Total solar output = 383x10^24W
total solar mass = 2x10^30kg (34% of which is in in the core, the inner 20% of the radius where virtually all the energy is actually produced)
W/kg = 191uW/kg (573uW/kg of core)
Re: Fusion is easy (Score:2)
Wow! Thank you for the fascinating explanation. The thing about power density was eye opening.
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Yeah, that really blew my mind the first time I heard it.
Re: Fusion is easy (Score:2)
Yeah.
What we need (if such a graph exists) is a multi-dimensional plot of the variables involved with fusion and the surface that represents probable break-even to be drawn. Then, for each experimental announcement, all of the parameters can be plotted and we can judge how far from that surface they have come. Sure, you can get 70 million degrees, but at what plasma density? Etc, etc.
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The problem is that we don't know the variables - what they even are depends almost entirely on the reactor design. (not just their values, but what properties are available to *have* values)
From the physics side, fusion (of light elements) always makes more energy than you put in. Simple. You just need the atoms to collide with each other fast enough to overcome their electrostatic repulsion, which is most easily accomplished by heating them to many millions of degrees.
The difficulty is that it's very unl