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(Phys Org2)   How far has nuclear fusion power come? We could be at a turning point for the technology just ten years from tomorrow   (phys.org) divider line
    More: Unlikely, Fusion power, fusion power, Nuclear fusion, global fusion industry, Private equity investment, government funding, world's most powerful operational tokamak, Nuclear power  
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476 clicks; posted to STEM » on 07 Dec 2022 at 2:56 PM (7 weeks ago)   |   Favorite    |   share:  Share on Twitter share via Email Share on Facebook



15 Comments     (+0 »)
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2022-12-07 2:34:39 PM  
"In recent years, several fusion experiments have also reached the all-important milestone of sustaining plasma temperatures of 100 million degrees Celsius or above. <...>

These incredible feats demonstrate an unprecedented ability to replicate conditions found inside our Sun and keep extremely hot plasma trapped long enough to encourage fusion to occur."


No. Stop it with this. Popsci articles on fusion all love to say that fusion reactors are trying to achieve the temperatures that exist in the core of the sun, but that is wrong.

The core of the sun is only about 15 million celsius.

As it says on the page (although it's fairly trivial to calculate yourself if you know the total solar luminosity and core volume,) the power density of the sun's core is only about an 276 W/m3. This is not a lot of power - the power density of the average human body is well over 1 kW/m3. The ~300 W number is most commonly compared to the power output of a compost pile. The sun only gets so hot and puts out so much power because it is unfathomably huge, but the relatively slow fusion reaction is what enables it to stay at a relatively stable output across billion-year timescales.

In fusion power research, running a reactor at that temperature would give you enough power to run maybe a hairdryer or two, which is far more power than the spend making and confining the plasma, which is why they put so much effort in getting plasmas to temperatures more that six times hotter than exist in the core of the sun.

(I don't think fusion power is around the corner, but I do think it's probably still worthwhile research, and that edgy cynicism about it never working shouldn't be confused for wisdom. A lot of times a technological principle is invented or understood, but the supporting technologies that make it viable take a lot longer. The Greeks knew how to use steam to spin a wheel, but it wasn't until the 1700s that metalurgy enabled reliable, non-explodey boilers. Most of the things enabled by modern battery technology, like increasingly popular EVs and commercial drones, are very, very old technology, but they didn't become commercially viable until battery technology caught up. Etc.

I do think a fusion reactor may turn out to have a minimum size, though.)
 
2022-12-07 3:00:13 PM  
It'll be ten or more years until we're only ten years away.
 
2022-12-07 3:12:40 PM  

Russ1642: It'll be ten or more years until we're only ten years away.


When I was much younger, other people were making the same jokes and I thought they were being pessimistic. Free energy and world peace were just around the corner. I was an idiot.

/I'm still an idiot.
//More realistic though.
///It's not around the corner, it's over the next dune.
 
2022-12-07 3:23:07 PM  
secure.img1-fg.wfcdn.comView Full Size


Something tells me that at least one of the scientists and engineers working at the NIH have this on the wall of their office.
 
2022-12-07 4:08:51 PM  
just as soon as Unix takes over the desktop, amirite?
 
2022-12-07 4:58:17 PM  
Martian_Astronomer:

Now I'm imagining a smartphone powered by a wheel of cats and amber rods
 
2022-12-07 6:17:29 PM  
Follow the money. It used to be only governments spending large amounts of moolah on fusion research, now a good chunk of that money is coming from deep pocketed private investors. One of them could eventually spring the equivalent of Ford's Model T on us, and you will want to buy in when they do.
 
2022-12-07 7:07:17 PM  

Martian_Astronomer: "In recent years, several fusion experiments have also reached the all-important milestone of sustaining plasma temperatures of 100 million degrees Celsius or above. <...>

These incredible feats demonstrate an unprecedented ability to replicate conditions found inside our Sun and keep extremely hot plasma trapped long enough to encourage fusion to occur."

No. Stop it with this. Popsci articles on fusion all love to say that fusion reactors are trying to achieve the temperatures that exist in the core of the sun, but that is wrong.

The core of the sun is only about 15 million celsius.

As it says on the page (although it's fairly trivial to calculate yourself if you know the total solar luminosity and core volume,) the power density of the sun's core is only about an 276 W/m3. This is not a lot of power - the power density of the average human body is well over 1 kW/m3. The ~300 W number is most commonly compared to the power output of a compost pile. The sun only gets so hot and puts out so much power because it is unfathomably huge, but the relatively slow fusion reaction is what enables it to stay at a relatively stable output across billion-year timescales.

In fusion power research, running a reactor at that temperature would give you enough power to run maybe a hairdryer or two, which is far more power than the spend making and confining the plasma, which is why they put so much effort in getting plasmas to temperatures more that six times hotter than exist in the core of the sun.

(I don't think fusion power is around the corner, but I do think it's probably still worthwhile research, and that edgy cynicism about it never working shouldn't be confused for wisdom. A lot of times a technological principle is invented or understood, but the supporting technologies that make it viable take a lot longer. The Greeks knew how to use steam to spin a wheel, but it wasn't until the 1700s that metalurgy enabled reliable, non-explodey boilers. Most of the things ...


Good explanation.

I never really needed to understand all the science to realize these "FUSION JUST AROUND THE CORNER" articles are BS.

It's the physics publication equivalent of a financial article telling you to invest in crypto. I usually lose interest once they start talking about a fusion generator like a mini-sun.

In some ways stars have it easier. They just need a big cloud of hydrogen gas, gravity and a little time for the cloud to collapse. We need super powerful lasers, magnetic containment fields and deuterium / tritium fuel pellets.

We're not trying to do is not "create a mini sun on earth". Saying that is like saying that building an electric generator is like trying to build a mini thunderstorm.

But what do I know? I ain't no smart scientician.
 
2022-12-07 7:25:59 PM  

fragMasterFlash: Follow the money.


I know you're going to think I'm a crazy person, but that's one of the reasons I still have suspicions about cold fusion. Imagine the social and political upheaval that would be caused by power that's both portable and (basically) free. Now, I believe what we've been told, but if there was a news story in a couple of decades that said cold fusion had been suppressed by people with money, I wouldn't be surprised.
 
2022-12-07 8:14:47 PM  

Dadoo: fragMasterFlash: Follow the money.

I know you're going to think I'm a crazy person, but that's one of the reasons I still have suspicions about cold fusion. Imagine the social and political upheaval that would be caused by power that's both portable and (basically) free. Now, I believe what we've been told, but if there was a news story in a couple of decades that said cold fusion had been suppressed by people with money, I wouldn't be surprised.


The people in power can't suppress a fart let alone a major discovery made by a research group not already housed at Area 51.
 
2022-12-07 8:32:24 PM  

Dadoo: I still have suspicions about cold fusion


I don't see anyone investing in cold fusion, not when cryptocurrency has already sucked up most of the rube's disposable income. There is however significant private capital invested into improving hot plasma containment research, and those dominoes appear ready to start falling.
 
2022-12-07 8:38:34 PM  

fragMasterFlash: Dadoo: I still have suspicions about cold fusion

I don't see anyone investing in cold fusion, not when cryptocurrency has already sucked up most of the rube's disposable income. There is however significant private capital invested into improving hot plasma containment research, and those dominoes appear ready to start falling.


external-preview.redd.itView Full Size
 
2022-12-07 9:42:13 PM  

Russ1642: The people in power can't suppress a fart let alone a major discovery made by a research group not already housed at Area 51.


Really? They did a pretty good job suppressing the fact that the tobacco companies were deliberately spiking their product with nicotine.
 
2022-12-07 10:12:06 PM  

Martian_Astronomer: I do think a fusion reactor may turn out to have a minimum size, though.)


I think that it's becoming more and more clear that fusion ENERGY will never be commercially viable. If we're very, VERY lucky, we might get a demonstration powerplant that runs for about 15 years that, while capable of producing net power to the grid, can only do so at 3 times the cost of fission and 10 times the cost of natural gas. IF we're lucky.

The science behind it will probably lead to the invention of things like fusion propulsion systems for spacecraft large scale research reactors. But fusion as a POWER source is as much a dead end as the Tesla Tower.
 
2022-12-07 10:37:32 PM  
Tell me more about proton boron fusion.
 
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