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I’m pessimistic this will ever be able to work. Doesn’t fusion require tremendous pressure that’s equivalent to the Sun’s gravity? How on Earth are we going to

by dlcmh 7y ago

I’m pessimistic this will ever be able to work. Doesn’t fusion require tremendous pressure that’s equivalent to the Sun’s gravity? How on Earth are we going to be able to generate such a pressure?

retSava 7y ago
Not a nuclear physicist, but IIRC sustainable fusion requires three factors: time, pressure, temperature. So far, you can basically choose two of them at a time, and much research goes into having all three at the same time. Needless to say, but it also requires loooooots of related research, eg materials to handle the magnetic flux, temperature, etc etc etc.
- willis936 7y ago
  Time has really been the killer. It’s been well understood since the beginning (a brief 60 years ago) how to make plasma hotter and more dense. We’ve learned about limits to pushing these two, but at the end of the day if confinement time was infinity then fusion would be trivial. The thing is even 10^-6 Torr conductive particles squeezed by a 1 Tesla field still like to drift outward and hit the wall. I cannot, in short form, explain how complicated this problem is. However there are no apparent show stoppers.
- jacknews 7y ago
  I think we can only really do 1 of them, temperature. Pressures are no-where near the core of the sun (300 billion bar), nor are confinement times (years). Which is why we use D-T fusion, which is not at all the same as the "clean, natural hydrogen fusion" in the sun. That whole "clean energy, like the sun" argument is fake.
deleted 7y ago
[deleted]
neuronic 7y ago
We already are. Instead of gravity, magnetic fields are used to compress hot plasma and cause it to reach very high temperature levels to allow fusion. Temperature is basically atomic/molecular movement and the more energetic the movement the more likely that crashing nuclei will react and fuse. There are currently two major magnetic field designs: - Tokamak, such as ITER [1] - Stellerator, such as Wendelstein-7X [2] [1] https://en.wikipedia.org/wiki/ITER https://en.wikipedia.org/wiki/ITER [2] https://en.wikipedia.org/wiki/Wendelstein_7-X https://en.wikipedia.org/wiki/Wendelstein_7-X
- Zardoz84 7y ago
  Don't forget magnetic mirrors
alpaca128 7y ago
Generating the necessary heat and pressure is already possible. The problem is keeping the whole process stable over long periods while getting more usable energy out of the fusion than is needed to maintain it, if I remember correctly the experiments so far had extremely short durations. Apparently Iter was designed to make sure the energy balance works out, but we'll see.
OJFord 7y ago
It's been made to work, as I recall from a visit to Culham, the problem is keeping it there. We can 'do fusion' briefly, and more expensively than the value of the energy produced.
willis936 7y ago
Some required, light reading. https://en.wikipedia.org/wiki/Lawson_criterion https://en.wikipedia.org/wiki/Lawson_criterion

by dlcmh 7y ago

retSava 7y ago

Not a nuclear physicist, but IIRC sustainable fusion requires three factors: time, pressure, temperature. So far, you can basically choose two of them at a time, and much research goes into having all three at the same time. Needless to say, but it also requires loooooots of related research, eg materials to handle the magnetic flux, temperature, etc etc etc.

willis936 7y ago
Time has really been the killer. It’s been well understood since the beginning (a brief 60 years ago) how to make plasma hotter and more dense. We’ve learned about limits to pushing these two, but at the end of the day if confinement time was infinity then fusion would be trivial. The thing is even 10^-6 Torr conductive particles squeezed by a 1 Tesla field still like to drift outward and hit the wall. I cannot, in short form, explain how complicated this problem is. However there are no apparent show stoppers.
jacknews 7y ago
I think we can only really do 1 of them, temperature. Pressures are no-where near the core of the sun (300 billion bar), nor are confinement times (years). Which is why we use D-T fusion, which is not at all the same as the "clean, natural hydrogen fusion" in the sun. That whole "clean energy, like the sun" argument is fake.

deleted 7y ago

[deleted]

neuronic 7y ago

We already are. Instead of gravity, magnetic fields are used to compress hot plasma and cause it to reach very high temperature levels to allow fusion. Temperature is basically atomic/molecular movement and the more energetic the movement the more likely that crashing nuclei will react and fuse. There are currently two major magnetic field designs: - Tokamak, such as ITER [1] - Stellerator, such as Wendelstein-7X [2] [1] https://en.wikipedia.org/wiki/ITER https://en.wikipedia.org/wiki/ITER [2] https://en.wikipedia.org/wiki/Wendelstein_7-X https://en.wikipedia.org/wiki/Wendelstein_7-X

Zardoz84 7y ago
Don't forget magnetic mirrors

alpaca128 7y ago

Generating the necessary heat and pressure is already possible. The problem is keeping the whole process stable over long periods while getting more usable energy out of the fusion than is needed to maintain it, if I remember correctly the experiments so far had extremely short durations. Apparently Iter was designed to make sure the energy balance works out, but we'll see.

OJFord 7y ago

It's been made to work, as I recall from a visit to Culham, the problem is keeping it there. We can 'do fusion' briefly, and more expensively than the value of the energy produced.

willis936 7y ago

Some required, light reading. https://en.wikipedia.org/wiki/Lawson_criterion https://en.wikipedia.org/wiki/Lawson_criterion