Possible fusion power plants of the future

In summary: The pressure is determined by the plasma density and temperature (P = nkT), and it is counter balanced by the magnetic field, which is limited by what field the superconducting magnets can provide. The temperature is determined by the energy balance in the plasma, with the goal that energy generated by fusion would greatly exceed the loses from the plasma.
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hagar
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Question about fusion power sources. An article I just read stated that they would be safe as if anything went wrong they would just stop working. Is this correct ? If so than why do stars continue to burn and seem (to me at least) to be self feeding.

Respectfully,
Pat Hagar
 
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hagar said:
An article I just read stated that they would be safe as if anything went wrong they would just stop working. Is this correct ?
If the plasma reaches the first wall, it loses heat rapidly, i.e., it is quenched and the fusion process would cease. The plasma density is on the order of 1014 particles/cm3.
hagar said:
If so than why do stars continue to burn and seem (to me at least) to be self feeding.
Think of the size of stars compared to the Sun or our planet, and then think about the size of a power plant compared to the plant. Stars are orders of magnitude greater in size and mass compared to a power plant [understatement].

The plasma density, temperatures and pressures are much, much greater than we could ever achieve in a terrestrial tokamak.

https://en.wikipedia.org/wiki/Solar_core
http://solarscience.msfc.nasa.gov/interior.shtml
https://fusedweb.llnl.gov/CPEP/Chart_Pages/5.Plasmas/SunLayers.html

The sun has been around for about 4.5 billion years, so it's remarkably stable. Occasional CMEs blow off a very small fraction of a percentage of solar mass.

If you're standing on the photosphere of the sun -- the "surface", the gravitational strength of the sun will be about 27.9 times that of the Earth, if you were standing on the surface of the Earth. In metric units, on Earth, the acceleration due to gravity is 9.81 meters/sec^2, so on the Sun, that would be 273.7 meters/sec^2.
Ref: https://van.physics.illinois.edu/qa/listing.php?id=1063
 
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This would be "safe" by comparison with nuclear fission plants.
 
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Astronuc said:
The plasma density, temperatures and pressures are much, much greater than we could ever achieve in a terrestrial tokamak.
The temperature in tokamaks (if they do fusion) is higher than in the core of sun, roughly a factor of 7.We don't have gravitational pressure, if anything goes wrong and the plasma containment gets lost. fusion stops immediately. In the worst case, some parts of the reactor wall will melt. Bad for the reactor, but not dangerous for anyone.
 
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mfb said:
The temperature in tokamaks (if they do fusion) is higher than in the core of sun, roughly a factor of 7.

Fascinating, I had no idea of this.

Than size,density and gravity controlling pressure and temperature would be the limiting factors.
Thanks to all for the responses and links.

Respectfully,
Pat Hagar
 
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There is no relevant gravity in the plasma on Earth. Pressure is maintained by the magnetic field.
 
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mfb said:
There is no relevant gravity in the plasma on Earth. Pressure is maintained by the magnetic field.

I thank you for the correction. My comment was not stated correctly. I meant the gravity of the sun maintains the pressure and temperature.

Respectfully,
Pat Hagar
 
  • #8
mfb said:
The temperature in tokamaks (if they do fusion) is higher than in the core of sun, roughly a factor of 7.
Thanks for the correction. I had switched the numbers.

hagar said:
Than size,density and gravity controlling pressure and temperature would be the limiting factors.
As mfb mentioned Earth's gravity is relatively weak. The pressure is determined by the plasma density and temperature (P = nkT), and it is counter balanced by the magnetic field, which is limited by what field the superconducting magnets can provide. The temperature is determined by the energy balance in the plasma, with the goal that energy generated by fusion would greatly exceed the loses from the plasma.
 
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Astronuc said:
Thanks for the correction. I had switched the numbers.As mfb mentioned Earth's gravity is relatively weak. The pressure is determined by the plasma density and temperature (P = nkT), and it is counter balanced by the magnetic field, which is limited by what field the superconducting magnets can provide. The temperature is determined by the energy balance in the plasma, with the goal that energy generated by fusion would greatly exceed the loses from the plasma.
Thank you for the correction, it seems I did it again. I was referring to the suns fusion process and not to a local power plant.

Respectfully,
Pat Hagar
 
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1. How does fusion power work?

Fusion power is the process of combining two or more atomic nuclei to form a heavier nucleus, releasing a large amount of energy in the process. This is the same process that powers the sun and other stars.

2. What are the potential benefits of fusion power?

Fusion power has the potential to provide a nearly limitless source of clean, sustainable energy. It does not produce greenhouse gas emissions or long-lived radioactive waste, making it a much safer and more environmentally friendly alternative to traditional fossil fuels.

3. What are the challenges of developing fusion power?

The main challenge of developing fusion power is creating the extreme conditions necessary for fusion reactions to occur. This requires very high temperatures and pressures, as well as containing the extremely hot plasma that is created. Additionally, the technology and materials needed to build and sustain a fusion reaction are still being developed.

4. When will fusion power become a reality?

Unfortunately, it is difficult to predict when fusion power will become a reality as it is a complex and ongoing research and development process. However, scientists and engineers are making significant progress and some estimates suggest that fusion power could become commercially viable within the next few decades.

5. What are the potential risks of fusion power?

One potential risk of fusion power is the release of radioactive materials in the event of a reactor malfunction. However, these risks are much lower than those associated with traditional nuclear power plants, and ongoing research is focused on making fusion power even safer. There is also the possibility of a runaway reaction, but this is highly unlikely due to the inherent instability of fusion reactions.

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