Can fusion power be proven impossible?

[barbos]

So I read about H-bombs on wiki and read a couple of the external links. It seems that there is enough fusion fuel to act as a self-insulation for loss of energy and mass. Basically, the fusion fuel is igniting more fusion fuel - there is not an opening for the reactants to leak out. Also the design and the fission helps trap all the fusion fuel and the reaction happens too fast for much loss.

The sun is the ultimate for self-insulation with how massive it is. Compare that to the tiny pellets used in these experiments.

Sun nuclear reactions are extremely slow because they are H-H not D-D.
if Sun was made of D it would burn out in microsecond or something. (OK I am talking out my ass here but I am probably right about microsecond)

 

[skepticalbip]

skepticalbip, "applied" is actual energy which fuel received from compression.
Compression using lasers is inherently inefficient because it's done through heating and evaporating material, most of the energy is taken away by that material flying away.
Nevertheless it's important benchmark and when ignition actually happens there will be a lot more fusion than they are currently getting.

Granted. This was an important step but it wasn't the "breakthrough" that it was touted to be by the media. They still have not reached the crucial step of igniting the fusion reaction, at least not that I have heard. When that happens, it's likely that everyone will know about it because it will be such big news. The fusion they are seeing is incidental to the compression forces of the x-rays. The real breakthrough will be when the fusion caused by this is what is compressing the fuel, ignition.

Until (and if) they are able to accomplish ignition, they will only see fusion levels on the order of a percent or so, at most, of the laser power applied.

 

[barbos]

skepticalbip, "applied" is actual energy which fuel received from compression.
Compression using lasers is inherently inefficient because it's done through heating and evaporating material, most of the energy is taken away by that material flying away.
Nevertheless it's important benchmark and when ignition actually happens there will be a lot more fusion than they are currently getting.

Granted. This was an important step but it wasn't the "breakthrough" that it was touted to be by the media. They still have not reached the crucial step of igniting the fusion reaction, at least not that I have heard. When that happens, it's likely that everyone will know about it because it will be such big news. The fusion they are seeing is incidental to the compression forces of the x-rays. The real breakthrough will be when the fusion caused by this is what is compressing the fuel, ignition.

It's not due to x-rays, it's ordinary laser light.

Until (and if) they are able to accomplish ignition, they will only see fusion levels on the order of a percent or so, at most, of the laser power applied.

I think you are confused by the large disparity between mega-joules delivered by lasers and mere kilojoules output.
Laser output is irrelevant, once ignition is achieved there will be instant and exponential increase in output. Apparent minuscule output does not say how close they are to ignition but that particular benchmark does say. It says that actual fusion becomes comparable with compression itself and becomes a factor.

 

[skepticalbip]

Granted. This was an important step but it wasn't the "breakthrough" that it was touted to be by the media. They still have not reached the crucial step of igniting the fusion reaction, at least not that I have heard. When that happens, it's likely that everyone will know about it because it will be such big news. The fusion they are seeing is incidental to the compression forces of the x-rays. The real breakthrough will be when the fusion caused by this is what is compressing the fuel, ignition.

It's not due to x-rays, it's ordinary laser light.

Until (and if) they are able to accomplish ignition, they will only see fusion levels on the order of a percent or so, at most, of the laser power applied.

I think you are confused by the large disparity between mega-joules delivered by lasers and mere kilojoules output.
Laser output is irrelevant, once ignition is achieved there will be instant and exponential increase in output. Apparent minuscule output does not say how close they are to ignition but that particular benchmark does say. It says that actual fusion becomes comparable with compression itself and becomes a factor.

No. the pellet is the fuel of deuterium and tritium encased in a plastic capsule all inside a metal shell (the hohlraum). The laser beams aren't aimed at the fuel but through holes in the hohlraum so they strike the inside of the metal. This heats so much that it emits x-rays. The x-rays cause the plastic capsule to implode compressing the fuel. The laser has to have enough power to generate sufficient x-rays. Not only that but the laser pulse has to be shaped properly so that the x-ray energy generates the proper force at the proper time during the compression.

The reason I make a big deal about the disparity between the laser energy and the energy released by fusion is that it is what the whole idea of generating power by fusion reactors is all about. If it is found that, even with ignition of the fusion process, the process can not be designed to burn a sufficient percentage of fuel to produce fusion power significantly higher than the power put into the system then the whole study was just interesting science, not an answer to our power problems.
.

 

[barbos]

It's not due to x-rays, it's ordinary laser light.

Until (and if) they are able to accomplish ignition, they will only see fusion levels on the order of a percent or so, at most, of the laser power applied.

I think you are confused by the large disparity between mega-joules delivered by lasers and mere kilojoules output.
Laser output is irrelevant, once ignition is achieved there will be instant and exponential increase in output. Apparent minuscule output does not say how close they are to ignition but that particular benchmark does say. It says that actual fusion becomes comparable with compression itself and becomes a factor.

No. the pellet is the fuel of deuterium and tritium encased in a plastic capsule all inside a metal shell (the hohlraum). The laser beams aren't aimed at the fuel but through holes in the hohlraum so they strike the inside of the metal. This heats so much that it emits x-rays. The x-rays cause the plastic capsule to implode compressing the fuel. The laser has to have enough power to generate sufficient x-rays. Not only that but the laser beam has to be shaped properly so that the x-ray energy generates the proper force at the proper time during the compression.

Ok, there seems to be different variants including this one with indirect heating via x-rays.

The reason I make a big deal about the disparity between the laser energy and the energy released by fusion is that it is what the whole idea of generating power by fusion reactors is all about. If it is found that, even with ignition of the fusion process, the process can not be designed to burn a sufficient percentage of fuel to produce fusion power significantly higher than the power put into the system then the whole study was just interesting science, not an answer to our power problems.

You don't understand my point. Ignition means reaction produce enough energy to sustain itself and what they currently have is roughly a parity.
energy delivered by lasers is utterly irrelevant, once it's ignited it will produce orders of magnitude more that that.

Also, thermodynamically speaking laser pulse energy is not lost at all, because it eventually adds up to the heating of the water and making a steam.
What is lost is inefficiencies of lasers themselves.

 

[skepticalbip]

It's not due to x-rays, it's ordinary laser light.

Until (and if) they are able to accomplish ignition, they will only see fusion levels on the order of a percent or so, at most, of the laser power applied.

I think you are confused by the large disparity between mega-joules delivered by lasers and mere kilojoules output.
Laser output is irrelevant, once ignition is achieved there will be instant and exponential increase in output. Apparent minuscule output does not say how close they are to ignition but that particular benchmark does say. It says that actual fusion becomes comparable with compression itself and becomes a factor.

No. the pellet is the fuel of deuterium and tritium encased in a plastic capsule all inside a metal shell (the hohlraum). The laser beams aren't aimed at the fuel but through holes in the hohlraum so they strike the inside of the metal. This heats so much that it emits x-rays. The x-rays cause the plastic capsule to implode compressing the fuel. The laser has to have enough power to generate sufficient x-rays. Not only that but the laser beam has to be shaped properly so that the x-ray energy generates the proper force at the proper time during the compression.

Ok, there seems to be different variants including this one with indirect heating via x-rays.

Of course there are. They are trying to initiate a fusion burn but haven’t yet been successful so they have to keep changing the test parameters to try to reach their goal. The pellet design and use of x-rays I described was the test design that was used in the “groundbreaking” test you cited. So far, none of the approaches they have tried has gotten them there so who knows what the next test design will be? Maybe gamma rays? Repeating the same test under the same parameters that didn’t ignite the fusion reaction would be a rather futile effort.

The reason I make a big deal about the disparity between the laser energy and the energy released by fusion is that it is what the whole idea of generating power by fusion reactors is all about. If it is found that, even with ignition of the fusion process, the process can not be designed to burn a sufficient percentage of fuel to produce fusion power significantly higher than the power put into the system then the whole study was just interesting science, not an answer to our power problems.

You don't understand my point. Ignition means reaction produce enough energy to sustain itself and what they currently have is roughly a parity.
energy delivered by lasers is utterly irrelevant, once it's ignited it will produce orders of magnitude more that that.

I understand your point but you seem to assume that once there is ignition that the reaction will continue until all the fuel is burned. It won’t. No one expects it to. But they do want to find a design that will burn the greatest percentage of the fuel possible. How much that is, is not known but is dependent on a lot of parameters and conditions that they will only be able to experiment with once they finally achieve ignition (if they manage to achieve ignition).

Also, thermodynamically speaking laser pulse energy is not lost at all, because it eventually adds up to the heating of the water and making a steam.
What is lost is inefficiencies of lasers themselves.

Indeed, but the energy in the laser pulse is only a very, vary minor part of the energy used in generating the fusion. The yield has to be sufficient to greatly exceed all the power going into the facility to be of any use as a power source for our grid.

 

[Loren Pechtel]

skepticalbip, "applied" is actual energy which fuel received from compression.
Compression using lasers is inherently inefficient because it's done through heating and evaporating material, most of the energy is taken away by that material flying away.
Nevertheless it's important benchmark and when ignition actually happens there will be a lot more fusion than they are currently getting.

Ignition already happens.

 

[barbos]

skepticalbip, "applied" is actual energy which fuel received from compression.
Compression using lasers is inherently inefficient because it's done through heating and evaporating material, most of the energy is taken away by that material flying away.
Nevertheless it's important benchmark and when ignition actually happens there will be a lot more fusion than they are currently getting.

Ignition already happens.

More like smoldering.
ignition is when it produce bigger bang than lasers themselves.

 

[barbos]

It's not due to x-rays, it's ordinary laser light.

Until (and if) they are able to accomplish ignition, they will only see fusion levels on the order of a percent or so, at most, of the laser power applied.

I think you are confused by the large disparity between mega-joules delivered by lasers and mere kilojoules output.
Laser output is irrelevant, once ignition is achieved there will be instant and exponential increase in output. Apparent minuscule output does not say how close they are to ignition but that particular benchmark does say. It says that actual fusion becomes comparable with compression itself and becomes a factor.

No. the pellet is the fuel of deuterium and tritium encased in a plastic capsule all inside a metal shell (the hohlraum). The laser beams aren't aimed at the fuel but through holes in the hohlraum so they strike the inside of the metal. This heats so much that it emits x-rays. The x-rays cause the plastic capsule to implode compressing the fuel. The laser has to have enough power to generate sufficient x-rays. Not only that but the laser beam has to be shaped properly so that the x-ray energy generates the proper force at the proper time during the compression.

Ok, there seems to be different variants including this one with indirect heating via x-rays.

Of course there are. They are trying to initiate a fusion burn but haven’t yet been successful so they have to keep changing the test parameters to try to reach their goal. The pellet design and use of x-rays I described was the test design that was used in the “groundbreaking” test you cited. So far, none of the approaches they have tried has gotten them there so who knows what the next test design will be? Maybe gamma rays? Repeating the same test under the same parameters that didn’t ignite the fusion reaction would be a rather futile effort.

The reason I make a big deal about the disparity between the laser energy and the energy released by fusion is that it is what the whole idea of generating power by fusion reactors is all about. If it is found that, even with ignition of the fusion process, the process can not be designed to burn a sufficient percentage of fuel to produce fusion power significantly higher than the power put into the system then the whole study was just interesting science, not an answer to our power problems.

You don't understand my point. Ignition means reaction produce enough energy to sustain itself and what they currently have is roughly a parity.
energy delivered by lasers is utterly irrelevant, once it's ignited it will produce orders of magnitude more that that.

I understand your point but you seem to assume that once there is ignition that the reaction will continue until all the fuel is burned. It won’t. No one expects it to.

I neither assume nor expect that. I am trying to explain you importance of their achievement.

But they do want to find a design that will burn the greatest percentage of the fuel possible. How much that is, is not known but is dependent on a lot of parameters and conditions that they will only be able to experiment with once they finally achieve ignition, if they manage to get to that point.

Also, thermodynamically speaking laser pulse energy is not lost at all, because it eventually adds up to the heating of the water and making a steam.
What is lost is inefficiencies of lasers themselves.

Indeed, but the energy in the laser pulse is only a very, vary minor part of the energy used in generating the fusion. The yield has to be sufficient to greatly exceed all the power going into the facility to be of any use as a power source for our grid.

Just saying that these particular mega-joules are not lost. So assuming lasers 100% efficient and fusion energy is about equal to the lasers input the whole thing becomes economically meaningful. Of course lasers are not more than 10% efficient.

 

[Tom Sawyer]

I saw one documentary which demonstrated that if Superman were to throw a punch at your face with his fist travelling at 99% of the speed of light, the the energy created by the passing of his fist through the air would fuse the air molecules together with enough power to vaporize everything within a 45 mile radius.

So ya, fusion power is easy. All you need is Superman and he's always ready to be helpful.

 

[Kharakov]

I saw one documentary which demonstrated that if Superman were to throw a punch at your face with his fist travelling at 99% of the speed of light, the the energy created by the passing of his fist through the air would fuse the air molecules together with enough power to vaporize everything within a 45 mile radius.

So ya, fusion power is easy. All you need is Superman and he's always ready to be helpful.

Hmm, thought it was a "What if?" from xkcd (haha, first what if!), but it was a vsauce (found via iflscience).

[video=youtube;V-fL8zopddI]https://www.youtube.com/watch?list=UUwmFOfFuvRPI112vR5DNnrA&feature=player _embedded&v=V-fL8zopddI[/video]

 

[skepticalbip]

Ignition already happens.

More like smoldering.
ignition is when it produce bigger bang than lasers themselves.

I like your "smoldering" - a quite apt analogy. Like the smoldering in a campfire before it ignites (or goes out), there is evidence that something is happening but it is useless for cooking or warming yourself by.

 

[Tom Sawyer]

I saw one documentary which demonstrated that if Superman were to throw a punch at your face with his fist travelling at 99% of the speed of light, the the energy created by the passing of his fist through the air would fuse the air molecules together with enough power to vaporize everything within a 45 mile radius.

So ya, fusion power is easy. All you need is Superman and he's always ready to be helpful.

Hmm, thought it was a "What if?" from xkcd (haha, first what if!), but it was a vsauce (found via iflscience).

Ya, that's the one. I just discovered vsauce over the weekend and am quite impressed with all the stuff they have. It's a cool series of videos.