Energy recovery coils

[Francisl]

I’ve watched the animations for the collapsing plasmoid and they show a positive beam traveling in one direction and a negative beam traveling in the opposite direction. There has been discussion about using energy recovery coils for the positive beam. Can’t coils also be used for the negative beam?

[zapkitty]

Francisl wrote: I’ve watched the animations for the collapsing plasmoid and they show a positive beam traveling in one direction and a negative beam traveling in the opposite direction. There has been discussion about using energy recovery coils for the positive beam. Can’t coils also be used for the negative beam?

As I understand it the negative beam is supposed to expend its energy on the plasmoid that created it… heating it even further and thus increasing the fusion yield and the positive beam output,.. so it would already be increasing the electrical output in an indirect manner.

[Aeronaut]

zapkitty wrote:

I’ve watched the animations for the collapsing plasmoid and they show a positive beam traveling in one direction and a negative beam traveling in the opposite direction. There has been discussion about using energy recovery coils for the positive beam. Can’t coils also be used for the negative beam?

As I understand it the negative beam is supposed to expend its energy on the plasmoid that created it… heating it even further and thus increasing the fusion yield and the positive beam output,.. so it would already be increasing the electrical output in an indirect manner.

Right, Zap. The negative beam is shown for completeness, even though its circuit is virtual- it heats the plasma even further. The problem illustrating it is that you have to show that ion stream being balanced by an electron beam in order to be believable to scientists. Of course that’s at odds with illustrating how the theory says it works…

[Francisl]

That brings up a related question because of Newton’s law that for every action there is an opposite and equal reaction. The positive beam is carrying a lot of energy and momentum but the negative beam should have relatively little energy and momentum. That means there is an unbalanced directional force on the plasmoid forcing it to move in the opposite direction from the positive beam. If the plasmoid doesn’t move much that would indicate that either there is a significant amount of momentum in the negative beam or the strong magnetic field in the DPF is transferring the reaction force to the DPF structure.
If there is a reaction force that is transferred to the DPF structure would the force be significant? Would a vibration be detectable? Could a resonant vibration occur in a DPF running in continuous mode?

[Aeronaut]

Francisl wrote: That brings up a related question because of Newton’s law that for every action there is an opposite and equal reaction. The positive beam is carrying a lot of energy and momentum but the negative beam should have relatively little energy and momentum. That means there is an unbalanced directional force on the plasmoid forcing it to move in the opposite direction from the positive beam. If the plasmoid doesn’t move much that would indicate that either there is a significant amount of momentum in the negative beam or the strong magnetic field in the DPF is transferring the reaction force to the DPF structure.
If there is a reaction force that is transferred to the DPF structure would the force be significant? Would a vibration be detectable? Could a resonant vibration occur in a DPF running in continuous mode?

Good question that I’d overlooked. FF’s 1st 2 scaling experiments were funded by NASA’s JPL, so if it were configured as an ion drive, the magnetic field would couple that impulse to the DPF structure, and from there to the ship’s frame. I’d hazard a guess that, configured as a fusion electric power plant, this kinetic energy would be conserved as the coils convert it into electricity and heat.

[nferguso]

I have been following FFS website activities for a few months with interest. I hope your society and the LPPX continue to prosper. Perhaps someone could help me with answers to a couple of non-scientist questions I can’t find the precise answer for.

I have gotten the impression that when a fusion of boron and hydrogen occurs in a FF device, it is the alpha particles produced by the fusion that will leave the reaction area, and it will leave in a beam axial to the electrodes rather than evenly in entirely random directions. Is this true? That would be the implication if “particle decelerator” mechanisms are to be used to capture the electric energy directly from the particle momentum. Oh, and if true, is it a single direction axially, or bidirectionally out both ends of the reaction area? The thread suggests it’s unidirectionally but I want to be sure.

Second, If the particles emerge from the reaction area in a beam rather than omnidirectionally, is it because the electromagnetic forces of the plasma focus them to do so, or is it because the boron and hydrogen particles have been guided to fusion so that the alpha particles are thrown off in a uniform linear direction? The latter doesn’t seem possible to me, but I’m no physicist.

The gist of the thread has me wondering. My understanding is that the “positive” beam is composed of high energy helium ions formed and accelerated by the fusion reaction. There is no corresponding beam of “negative” electrons with equivalent energy created by the fusion, is there? The reaction is nuclear, not electrical. Is my layman’s understanding at all close? Or have I missed the point entirely?

[Ivy Matt]

I’m not a scientist either, but my understanding is that the beams are produced by strong magnetic fields in the plasmoid. As a plasma consists of unbound positive ions and negative electrons, the ions will exit the plasmoid in one direction (“outward”) while the electrons will (theoretically: see the discussion above) exit the plasmoid in the opposite direction (“inward”). This happens independently of whether or not any fusion reactions take place. Any neutral particles and electromagnetic rays will radiate in all directions, as they are not affected by the magnetic fields.

Note that the concentrated ion beam is a result of the plasma focus design. In a Polywell fusion reactor, for example, the alpha particles would radiate in all directions.

[nferguso]

Thanks, Ivy Matt. It’s still not making sense to me. It is the product of the fusion, the high energy helium nuclei (alpha particles), that carries the output energy of the system, is it not? Isn’t that what the focused beam will consist of? When talking about the plasmoids, aren’t we talking about different stuff – plasma created from the current from the capacitors that compresses ambient fuel to produce the fusion?

Wouldn’t it be the case that if the components of the fusion-triggering plasma do end up in the beams, they are there only incidentally? Isn’t the great majority of the energy in the beam specifically the alpha particles?

Cheers,
Neil Ferguson

[Aeronaut]

nferguso wrote: Thanks, Ivy Matt. It’s still not making sense to me. It is the product of the fusion, the high energy helium nuclei (alpha particles), that carries the output energy of the system, is it not? Isn’t that what the focused beam will consist of? When talking about the plasmoids, aren’t we talking about different stuff – plasma created from the current from the capacitors that compresses ambient fuel to produce the fusion?

Wouldn’t it be the case that if the components of the fusion-triggering plasma do end up in the beams, they are there only incidentally? Isn’t the great majority of the energy in the beam specifically the alpha particles?

Cheers,
Neil Ferguson

Welcome to FFS, Neil. Yes, a large portion of the plasmoid’s energy is released in a beam of helium ions traveling at near relativistic speeds. They’re slowed in the recovery coils as their magnetic field and speed induce electric current in the energy recovery coils. Another large chunk of the plasmoid’s energy is radiated in the form of X-rays (Bremstrahlung radiation). Heat is the third major energy produced, and many of the system’s components will need active cooling. The general consensus seems to be high pressure helium for a number of reasons.

The machine has an axial phase, where the donut runs down the electrodes, followed by the kinking in the radial phase, where the collapsing magnetic fields from hopefully several million amps, for around a millionth of a second, will crush the plasmoid into a near-solid around 9nm across, where the fusion reactions are thought to occur. We’re hoping for 10 to 12 GG.

I’m not a physicist either. The easiest way I can relate to all of this is in terms of electro-magnetics. By following the current and resulting fields, you can understand just about everything outside of the plasmoid.

btw- the ion beam carries half of the plasmoid’s energy. The electron beam leaving the other end is absorbed by and heats the plasmoid further, which speeds up the rate of reactions. No single fusion produces much energy to speak of, but with a plasmoid producing somewhere between millions and billions of these reactions in the space of around 10nS, commercial quantities of energy can be produced (hopefully).

Hope this makes it all clearer.

[nferguso]

Hi. Yes, that’s what is still confusing me. Maybe it’s the word “plasmoid”. I take that word to refer to the stuff that is being pinched, producing fusion of H and B ions. It’s what’s there before fusion. The helium ions are a product of the fusion. That’s two different things. The fusion doesn’t produce electrons; at least Wikipedia doesn’t mention them. So if someone refers to even just a virtual beam of electrons, if they’re implying high-energy (as in MeV) electrons, I don’t see where they exist. The only highly energetic matter in a beam would be the He nuclei.

If we’re talking about the material remnants of the plasmoid (and if that word means what I think it means), and if the story is that the nuclear and electron particles also end up in a beam coming out of the reaction area, ok, but they would be relatively low energy (kV) and unimportant. I might like to know just out of curiosity if that part of the beam is formed before, during, or after fusion occurs.

Corollarily, would there not also be two distinct bursts of (x-ray/gamma-ray/heat) radiation to consider – a large amount from the fusion, and a smaller amount during the production, compression, and collapse of the plasmoid? Naturally, all the radiation would be omnidirectional, though perhaps not uniform.

Cheers,
Neil

[JimmyT]

Eric’s term “plasmoid” actually refers to the tiny ball made of plasma filaments.

Plasma, except perhaps for jets. must be electrically neutral. That is it must contain a roughly equivalent number on protons in its constituent nuclei, and electrons either bound or free. At these high energies they are all free.

The beam is not a direct result of the fusion reactions. It is a result of the collapsing magnetic field which is confining the plasma which makes the plasmoid. This collapsing field accelerates the electrons in the plasma in the opposite direction as the nuclei. The fusion reactions in turn fuel the magnetic field. I’m not sure we understand how exactly. Eric might.

As to the electron’s energy, Eric believes that in the process of spiraling around in the filaments which make up the plasmoid; they will transfer most of their momentum to the helium nuclei.

[Aeronaut]

A lot of this is explained in this month’s update, which contributors get a few days before it gets posted here. Of particular importance is how the sensors are arranged and interpreted – and the underlying theory.

The beam is entirely high energy he ions, balanced by the virtual beam (great term, btw!) of high energy electrons. Hmm… rapidly leaving the parts I have some kind of handle on…

[nferguso]

…waiting for update…

[Ivy Matt]

Would this update be for November, December, or both months?

[vansig]

nferguso wrote: Hi. Yes, that’s what is still confusing me. Maybe it’s the word “plasmoid”. I take that word to refer to the stuff that is being pinched, producing fusion of H and B ions. It’s what’s there before fusion. The helium ions are a product of the fusion. That’s two different things. The fusion doesn’t produce electrons; at least Wikipedia doesn’t mention them. So if someone refers to even just a virtual beam of electrons, if they’re implying high-energy (as in MeV) electrons, I don’t see where they exist. The only highly energetic matter in a beam would be the He nuclei.

If we’re talking about the material remnants of the plasmoid (and if that word means what I think it means), and if the story is that the nuclear and electron particles also end up in a beam coming out of the reaction area, ok, but they would be relatively low energy (kV) and unimportant. I might like to know just out of curiosity if that part of the beam is formed before, during, or after fusion occurs.

Corollarily, would there not also be two distinct bursts of (x-ray/gamma-ray/heat) radiation to consider – a large amount from the fusion, and a smaller amount during the production, compression, and collapse of the plasmoid? Naturally, all the radiation would be omnidirectional, though perhaps not uniform.

During the reaction, individual fusion products are trapped by the high magnetic fields in the plasmoid. The exit beam is the final result, as those fields collapse at the end.. after the bulk of fusion has taken place.

The electron beam width is much more spread out and cooler than the ion beam, and traveling in the opposite direction. The ion beam is tightly focused.

Individual fusions emit almost no gammas or neutrons, as those are side-reactions only (.1%)

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