Tri-Alpha recent patent reject.

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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KitemanSA
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Post by KitemanSA »

Tom Ligon wrote: Bussard stipulated that the p-B11 machines must have "virtual anode height" controlled. We've seen a couple of papers targeting about 15% of well depth. Thus, if you had 100 kV of well depth (and 500 keV of kinetic energy on the boron ions at +5 charge), the electrons would be at only 15 keV, presuming the system does not thermalize. Control of the virtual anode height essentially means you have to fuel starve the reactor a little, keeping ion density down.

WB6 did not need to keep the electrons cold because it was a DD machine and bremsstrahlung is not a big issue with that fuel. It had no mechanism for ion control, and probably ran only for a fraction of a millisecond as the ion population increased exponentially. But when it was working it would most likely have passed thru a zone in which the virtual anode height was low.
I was under the impression that the primary means of controlling brem in the p-¹¹B machine was to boost the "p" relative to B to maintain the fusion rate but lower the relative z. No?

happyjack27
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Post by happyjack27 »

well i hear microsoft is puttingtheir money into this. if they're also influencing the ip rights stuff then it's no surprise that they're criticized for insufficient disclosure. -it's apropo.

Tom Ligon
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Post by Tom Ligon »

Kiteman,

Diluting with about 8:1 p to B to reduce effective Z is another part of the brem reduction strategy.

The fact that the machine is electrodynamic offers the final benefit. Since the boron has a charge of +5, it winds up with 5x the kinetic energy of the protons. I think the protons end up a bit faster due to their low mass. Since fusion rate is actually a function of relative velocity rather than kinetic energy, that's good.

I've had in the back of my mind that the electrons are "cool" only in the center of the machine. They're fast as hell near the magrid, and that is probably where the dilution pays off. Fuel does hit pretty high density in the band where it slows down and turns around.

D Tibbets
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Post by D Tibbets »

mattman wrote:I can't speak for everything here - however I noticed the rejection included an important point about getting the electrons cold. The polywell has a similar issue. If the electrons in the middle were cold, unmoving, this would be helpful for the machine working. Ion to electron energy transfer would be low - ions are about 1,000 times more massive then electrons. So if the electrons are cold it would not necessarily mean the ions would also be cold.

Some people have made the argument that the electrons in the center of the polywell are cold, moving at low speeds. I am not so sure this was true in WB-6. The electrons are certainly experiencing A VERY LOW Lorenz force in the center. With no fields from the magnets in the center, the only Lorenz force the electrons experience would be caused by the movement of other electrons and ions - I think. No force means no acceleration. No acceleration means no new energy added to the electrons. .....
I think you are confused. Magnetic fields have nothing to do with acceleration. They can only change the vector of a charged particle. In the simplest system they change the direction by 90 degrees. But, there are other complexities, such as gyroradii, bouncing (or mirroring), magnetic field entry angle, magnetic field strength gradient, etc. to consider. When the magnetic field strength changes rapidly in comparison to the charged particle speed, the particle can be nearly reversed (180 degree turn) and travel nearly in the opposite direction from it's initial direction. The quasi sphericity of the magnetic surfaces are important in this regard to help maintain a central focus/ confluence of the electrons. The speed change of the electrons is due to the electrostatic forces between the charged particles. Starting with the kinetic energy and vector they receive from the electron gun, and the symmetric positive charge on the magrid areas surrounding a cusp, the electrons shoot towards the center. In this spherical geometry, as the electrons approach the center they are concentrating into a smaller volume and mutual repulsion slows and reverses them. Ideally they then accelerate away from the center until they are reversed at the Wiffleball / magnetic border, and start a new cycle. In an ideal system this would continue indefinitely. But with curving of the magnetic surfaces away from the center, thermalization issues, cusp loss issues, ion interaction issues, etc, the process becomes extremely complex. The goal is not to have an ideal perfect system, but through a series of compromises, to have a system that is good enough.

There is no magnetic field inside the Wiffleball border to effect the charged particals. The magnetic field from the magrid is excluded. There are of course localized magnetic effects on the charged particles, but the net effect of these local interactions average out to zero. In contrast to Tokamaks, stellorators, Tri- Alpha FRC (?) the Polywell fusion plasma is not magnetic (within the Wiffleball).

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

Ivy Matt
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Post by Ivy Matt »

happyjack27 wrote:well i hear microsoft is puttingtheir money into this.
Microsoft? Or just Paul Allen? Bill Gates and Nathan Myhrvold have invested in TerraPower (nuclear fission), and Gates was rather dismissive of fusion at his TED talk.

mattman
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Post by mattman »

OK,

We should just build a polywell, fill it with electrons, and do Thomson scattering to determine electron structure and energy.

That is a very hard measurement to do, but they already do it with Inertial Confinement Fusion.

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