The end of the world? Or the end of fossil fuels?

Discuss how polywell fusion works; share theoretical questions and answers.

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Stoney3K
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The end of the world? Or the end of fossil fuels?

Post by Stoney3K »

Just a little discussion going after a little brain-fart I had this afternoon, when reading the news.

I was wondering, why we're building all of these new machines when we might have a really viable option of getting there, already in place...

It's 18 miles long, and crosses the border of France. Enough hints?

I mean, everything we're trying to do here is an attempt to get ions to go fast enough to smash together and fuse. The LHC is a machine designed to do just that: Smash ions together. And with a big bang. The machine is designed to throw protons around with an energy of 3,5 TeV (yes, TERA-electron-volts) per proton injected. Which is quite some orders of magnitude bigger than the 10 keV required for D-T or even the 123keV required for p-B11.

So, my question is, aren't we already there by a very, very large margin? Isn't the Large Hadron Collider actually the world's biggest ICF machine in existence? And if not, would it be possible to adapt LHC-like topology to ICF to make it more viable? The only thing we don't have in the LHC is a way to extract any neutrons or ions for power production, but all of the other elements (vacuum, acceleration, beam confinement) are already there. And there are quite a few particle accelerators in the world that don't produce LHC-level energies, but will probably crank out enough grunt to accelerate fuel ions to the required energy.

I could think of a concept that works similar to the LHC and is just smaller. In case an ion misses, it just loops around for another go. It's different from a tokamak, since toks have a plasma in equilibrium, and fusion occurs everywhere around the circumference. In a 'beam-beam' fusion device derived from the LHC, fusion will only occur at one point of impact.

I wonder whether the LHC scientist already witnessed some fusion events during the device's operation. Maybe the proton densities are not high enough for that by intention, but I can imagine a proton smashes into another once in a while.
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blaisepascal
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Re: The end of the world? Or the end of fossil fuels?

Post by blaisepascal »

Stoney3K wrote:I wonder whether the LHC scientist already witnessed some fusion events during the device's operation. Maybe the proton densities are not high enough for that by intention, but I can imagine a proton smashes into another once in a while.
Since the whole intention of the LHC is to smash protons into one another, and they've announced they've already had proton collisions, I'd say yes, a proton smashes into another once in a while.

As for the rest, and fusion events....

Here's an analogy... Imagine a ball of water floating in zero-g. It's wibbly and wobbly, but roughly spherical. If you have two of them, and gently push them together, the surface tension of the two balls will keep them separate, and they will actually bounce. If you push them together harder, enough to overcome the surface tension, they will fuse together into one big wibbly ball. The harder they collide, the wibblier they are when they fuse. The larger they are, the more wibbly they are. If they get too wibbly, they'll break up into smaller balls.

A polywell tries to pull the water balls together hard enough to fuse. the LHC is trying to study the splash you get when you drop the balls from the equivalent of the top of the Empire State Building.

There are lots of losses involved with a synchrotron machine like LHC. Whenever you accelerate a charged particle, you get Bremsstrahlung radiation. One of the reasons to bury the ring is as radiation shielding. Particle accelerators are one of the, if not the, most powerful X-Ray sources made by man, and those X-Rays are used for research purposes as well. But they constitute a loss for power generation.

Stoney3K
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Re: The end of the world? Or the end of fossil fuels?

Post by Stoney3K »

blaisepascal wrote:Here's an analogy... Imagine a ball of water floating in zero-g. It's wibbly and wobbly, but roughly spherical. If you have two of them, and gently push them together, the surface tension of the two balls will keep them separate, and they will actually bounce. If you push them together harder, enough to overcome the surface tension, they will fuse together into one big wibbly ball. The harder they collide, the wibblier they are when they fuse. The larger they are, the more wibbly they are. If they get too wibbly, they'll break up into smaller balls.
I doubt the LHC can only be 'on' or 'off' and therefore is incapable of producing lower energies that are enough to generate fusion events, but not so much overkill that the strong nuclear forces are shattered along with the weak and electrostatic ones, leaving us no protons to fuse with! ;)

A Polywell is also a type of particle accelerator, albeit a spherical one instead of a linear or circular (synchrotron, or LHC) type. So it produces just as much Bremsstrahlung as another type of machine would, to accelerate the fuel past it's threshold energy, right?

The fact of the matter may be that the LHC is just too big. But doesn't that just mean we've already reached the potential energies required a long, long time ago?
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D Tibbets
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Post by D Tibbets »

Producing fusion is very easy and cheap. It has been done at least since the 1930's when accelerator use began. The trick is to produce fusion at a net profit. That is very difficult to do. Atom smashers at energies of a few MeV or more may actually produce less usefull fusion. The goal is to overcome the coulomb repulsion with enough energy to 'gently' push the necleons together, the strong force then takes over and compleates the fusion. To much energy and the nucleons may smash each other apart, and in the process scatter various particles. Many, if not most, of these particles are endothermic (a net negative energy balance).

Bremmstrulung radiation is a significant problem for the Polywell. According to Bussard, cyclotron radiation is not.

The only process that I know of where atom smashers/ acceleraters of more than a few million electron volts may be useful is in muon catalized fusion. But,it has it's own set of problems- see the wikapedia article on 'muon catalized fusion'.

Dan Tibbets
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93143
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Post by 93143 »

There's no reason you couldn't make a 200 kV cyclotron. But most collisions (especially glancing ones) don't result in fusion, and if there's even a small change in a particle's direction it is NOT going to make it all the way back around for another pass - it's going to embed itself into the wall, and that will be the end of that.

Fusion is easy. Fusion that produces energy at a rate high enough to offset the losses is not.

chrismb
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Post by chrismb »

93143 wrote:There's no reason you couldn't make a 200 kV cyclotron. But most collisions (especially glancing ones) don't result in fusion, and if there's even a small change in a particle's direction it is NOT going to make it all the way back around for another pass - it's going to embed itself into the wall, and that will be the end of that.

Fusion is easy. Fusion that produces energy at a rate high enough to offset the losses is not.
So, 93143, if a device could be configured such that a non-fusing scattered ion is recovered back into the beam and carries on around again (and repeats as many times as necessary before it gets to fuse), then you'd give such a device some serious attention as a possible means forward for fusion?

TDPerk
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Post by TDPerk »

"So, 93143, if a device could be configured such that a non-fusing scattered ion is recovered back into the beam and carries on around again (and repeats as many times as necessary before it gets to fuse), then you'd give such a device some serious attention as a possible means forward for fusion?"

Come now Chrismb, quit asking such circular suggestions in a roundabout way.
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hanelyp
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Post by hanelyp »

chrismb wrote:So, 93143, if a device could be configured such that a non-fusing scattered ion is recovered back into the beam and carries on around again (and repeats as many times as necessary before it gets to fuse), then you'd give such a device some serious attention as a possible means forward for fusion?
That, roughly, is what a polywell tries to do, using an excess of electrons in the plasma to accelerate ions into the center of the device.

Stoney3K
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Post by Stoney3K »

hanelyp wrote:
chrismb wrote:So, 93143, if a device could be configured such that a non-fusing scattered ion is recovered back into the beam and carries on around again (and repeats as many times as necessary before it gets to fuse), then you'd give such a device some serious attention as a possible means forward for fusion?
That, roughly, is what a polywell tries to do, using an excess of electrons in the plasma to accelerate ions into the center of the device.
Here's my vision on it, in lament's terms:

Objective: Smash together two ping pong balls, fast enough for them to turn into one large one, but not too fast to slam them into oblivion.

Tokamak approach: Dump a lot of ping pong balls into a football stadium, and create an earthquake that you hope is big enough to smash the balls together at random.

Polywell approach: Dig a large hole at the middle of the stadium, drop ping pong balls in there. Sooner or later they'll smash, right?

Synchrotron approach: Get two Major League baseball pitchers and let them try to throw ping pong balls at each other. Hope they don't throw a home run and miss.

Nature's approach: Just make sure you have enough ping pong balls, they'll stick together through their own mass anyway. :mrgreen:
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Art Carlson
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Post by Art Carlson »

Stoney3K wrote:Polywell approach: Dig a large hole at the middle of the stadium, drop ping pong balls in there. Sooner or later they'll smash, right?
Except it's not in a stadium, it's at the beach. As soon as you dig the hole, the sand starts flowing in again. The ping pong balls have to smash before the hole fills up.

D Tibbets
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Post by D Tibbets »

Art Carlson wrote:
Stoney3K wrote:Polywell approach: Dig a large hole at the middle of the stadium, drop ping pong balls in there. Sooner or later they'll smash, right?
Except it's not in a stadium, it's at the beach. As soon as you dig the hole, the sand starts flowing in again. The ping pong balls have to smash before the hole fills up.
That is a good discription of a dynamic system like the Polywell. Defining questions would then be how fast does the sand flow back into the hole and how much work do you have to do to keep digging it out.

Dan Tibbets
To error is human... and I'm very human.

alexjrgreen
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Post by alexjrgreen »

chrismb wrote:So, 93143, if a device could be configured such that a non-fusing scattered ion is recovered back into the beam and carries on around again (and repeats as many times as necessary before it gets to fuse), then you'd give such a device some serious attention as a possible means forward for fusion?
Is this what you're experimenting with?
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Stoney3K
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Post by Stoney3K »

chrismb wrote:So, 93143, if a device could be configured such that a non-fusing scattered ion is recovered back into the beam and carries on around again (and repeats as many times as necessary before it gets to fuse), then you'd give such a device some serious attention as a possible means forward for fusion?
Here's my thought on it:

In most 'current' IC machines, the same mechanisms are used both to accelerate the ions to a sufficient energy as well as confine them in the core. For a fusor/Polywell type device, this is done through electric fields.

My idea is that these mechanisms only need to confine the ions in a certain spot long enough to let them impact, and add the neccessary energy through external means. Here's a diagram of what I'm thinking of:

Image

Shown here is a synchrotron storage ring with 6 segments in a hexagon (for convenience of demonstration) which accelerates the fuel ions to the desired energy. On a point-of-impact at the corner, the ions will slam together and (possibly) fuse, but to keep the ions in the right place when they're undergoing fusion, they need a small nudge inward. Something like a lower-voltage Fusor grid or MaGrid could be useful for that.

Any ions that miss the boat altogether will go around for another loop, any non-fused, low-energy ions that are scattered will cause no harm and stay in the core until they get recovered by the vacuum system.
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Art Carlson
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Post by Art Carlson »

Stoney3K wrote:... any non-fused, low-energy ions that are scattered will cause no harm and stay in the core until they get recovered by the vacuum system, ...
taking with them the energy you invested in them with so much love and caring. Bzzzzz! You lose.

Stoney3K
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Post by Stoney3K »

Art Carlson wrote:taking with them the energy you invested in them with so much love and caring. Bzzzzz! You lose.
That energy has got to go somewhere, though. If the stuff hits the wall, part of it can be recovered through the cooling circuit and waste heat recovery (e.g. Stirling engine), but the entire endeavour is meant to prevent that from happening, and to get the most misses back in the loop so they can recover their energy.

As far as ideas go, I've seen more stupid endeavours get funding, just because they talk so much (like the SEG, which is a dead obvious fraud!), and I'm in favour of anything that thinks outside the (toroidal) box.
Because we can.

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