EMC2 has published a polywell preprint on arXiv

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

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ladajo
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Re: EMC2 has published a polywell preprint on arXiv

Postby ladajo » Fri Jun 13, 2014 12:11 am

Nope, it does not.
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

D Tibbets
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Re: EMC2 has published a polywell preprint on arXiv

Postby D Tibbets » Fri Jun 13, 2014 5:08 am

I think this is the paper that is one of Dr Parks key references.

http://www.archive.org/stream/theoryofc ... 5/mode/2up

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

mattman
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Re: EMC2 has published a polywell preprint on arXiv

Postby mattman » Fri Jun 13, 2014 7:00 pm


pbelter
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Re: EMC2 has published a polywell preprint on arXiv

Postby pbelter » Fri Jun 13, 2014 8:18 pm

Alan Boyle has a new article on EMC2

http://www.nbcnews.com/science/science- ... ey-n130661

"Low-Cost Fusion Project Steps Out of the Shadows and Looks for Money"

EMC2 Fusion is planning a three-year, $30 million commercial research program to see if its unorthodox approach can provide a fast track to cheap nuclear fusion power

Roger
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Re: EMC2 has published a polywell preprint on arXiv

Postby Roger » Fri Jun 13, 2014 8:45 pm

I like the p-B11 resonance peak at 50 KV acceleration. In2 years we'll know.

choff
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Re: EMC2 has published a polywell preprint on arXiv

Postby choff » Fri Jun 13, 2014 9:49 pm

One thing I picked up from the paper was this in regard to figure 6.

At B=0.6 kG, the x-ray result shows
changes in electron beam con nement property but the
signal is complex to interpret. In comparison, the x-ray
result clearly shows a well-de ned period of large increase
in electron beam con nement at B=2.7 kG. The excluded
magnetic
ux shows faster peaking and bigger diamag-
netic e ects at B=0.6 kG compared to B=2.7 kG. The
peak
ux exclusion for the B=0.6 kG case is equivalent
to 44% of the vacuum magnetic
ux, compared to 10%
for B=2.7 kG. The injected plasma density is compara-
ble initially, while the density decays rather rapidly for
B=0.6 kG.

Sorry about the formatting, but what I get is that they have a higher beta at lower magnetic field strength for the same amount of plasma, while still having comparable confinement. That could either mean diminishing returns for confinement with bigger magnets, or, there's a sweet spot for high beta conditions that only requires intermediately strong magnets. I think I heard the word relaxed in describing to the Skunkworks configuration somewhere. It would be hard to believe both projects never collaborated or exchanged notes, especially if they did find a sweet spot from experimenting with the knobs.
CHoff

D Tibbets
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Re: EMC2 has published a polywell preprint on arXiv

Postby D Tibbets » Fri Jun 13, 2014 11:03 pm

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

classicpenny
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Re: EMC2 has published a polywell preprint on arXiv

Postby classicpenny » Fri Jun 13, 2014 11:38 pm

pbelter wrote, "Alan Boyle has a new article on EMC2: EMC2 Fusion is planning a three-year, $30 million commercial research program to see if its unorthodox approach can provide a fast track to cheap nuclear fusion power"

I have three multi-part questions:
1. Is the Navy still interested in the Polywell. If they are, why did they stop funding it?
2. If the Navy is still interested and the beta=1 wiffleball has been demonstrated, why isn't the US Department of Energy taking over and developing the full-scale Navy Nuclear Power System. It is their Congressionally Mandated job to do so. What is going on here?
3. Is it possible that Dr. Park is only asking for $30 million because he knows the VC people will never fund the full scale Polywell unless its a "sure thing"? And are we going to waste three more years "making sure?" I can see that that the potential rewards of a successful Polywell are BIG enough that in this case IT IS WORTH THE RISK to go for the full-scale machine at this point. Or am I missing some really important information here that both Dr. Bussard and Dr. Nebel also somehow missed?

I really want to know these things and I welcome any and all speculation - and if someone gets a chance to ask Dr. Park, all the better!

Bill Flint

Robthebob
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Re: EMC2 has published a polywell preprint on arXiv

Postby Robthebob » Sat Jun 14, 2014 12:04 am

1. Talk to ladajo

2. I'm gonna take a stab at it and say that because DoE is too invested with their current projects; I mean they didnt help when Bussard was looking for money, granted it's different back then, it was like, Bussard saying, "take my word for it." However, Park is saying, "look at the numbers."

I dont think DoE will help until after the demo is built and running; you cant argue anything when the gauge is reading positive. There are a couple people (some of them members of this forum) that has pieces of the story, I feel that at some point it may be useful to start writing down everything that has happened.
Throwing my life away for this whole Fusion mess.

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Re: EMC2 has published a polywell preprint on arXiv

Postby paperburn1 » Sat Jun 14, 2014 12:23 am

I can,t even get funding for a bigger ac unit for a network critical infrastructure. That much free money does not exist right now so 30 million.... not a chance.
I am not a nuclear physicist, but play one on the internet.

John Gallagher
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Re: EMC2 has published a polywell preprint on arXiv

Postby John Gallagher » Sat Jun 14, 2014 5:18 pm

The first wall problem for DT and the production of Tritium are known to be difficult engineering problems with fusion systems. I have often wondered how a large flux of high energy alphas would be handled in this geometry. Their interaction with the magnet housing and the coils themselves would make for an interesting thermal management problem. Also the alpha flux is not exactly a beam than can be decelerated as in a direct conversion device. I know that people have put a lot a effort and thought into this. I was wondering if anyone can tell me where to find information on these subjects.

hanelyp
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Re: EMC2 has published a polywell preprint on arXiv

Postby hanelyp » Sat Jun 14, 2014 6:55 pm

Alphas produced in a polywell would be mostly channeled through cusps in the magnetic field. From there it's through an electron recirculation grid, and across a potential gap to the direct conversion collector. The biggest obstruction I see in the path is the electron injectors.
The daylight is uncomfortably bright for eyes so long in the dark.

ladajo
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Re: EMC2 has published a polywell preprint on arXiv

Postby ladajo » Sat Jun 14, 2014 8:30 pm

Not all the cusps would need to have Electron injectors.
In fact, an emitting gun would act to some degree as a cusp "Alpha Plug" given the streaming of (e-) in, and the fact that other cusps with guns could provide an out.

Everyone seeks the path of least resistance right?
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)

What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

D Tibbets
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Re: EMC2 has published a polywell preprint on arXiv

Postby D Tibbets » Sat Jun 14, 2014 10:07 pm

Alphas do not impinge on the magrid hardly at all, so thermal loading of the magnets by alpha particles is a non issue. According to Nebel, provided the B field is great enough relative to the machine radius, the alphas will be turned by the B field (gyroradius) and return towards the center. It will continue in this manner till it hits a cusp (after ~ 1000 passes according to Nebel, or what ever the Wiffleball trapping factor is). After escaping through a cusp it can transfer its energy by hitting the wall like other escaping charged particles or neutrons, or it could be decelerated with direct conversion. Admittedly direct conversion with the distributed cusps would be complicated. But, you do not need to capture all of the energy by direct conversion, even capturing 50% of the energy puts you ahead in the game from several perspectives.
ExB diffusion is trivial for the alphas. With KE in the MeV, the Coulomb collision cross section is very small (scales as 1/ KE^2)so there are only rare collisions to drive ExB drift/diffusion. This is also why alphas do not contribute much to plasma heating inside the machine. No ignition is possible or desired.

For the magrids the issue of external heating applies to neutrons if present in significant numbers (D-D and D-T fuel) and Bremsstruhlung radiation. Cyclotron radiation is relatively trivial. Also, fuel ions (or electrons) could heat the magnets through ExB drift, or by impacting exposed nubs if present. From the patent application it is mentioned that ExB losses will amount to ~ 1 % of the cusp losses. So, if your cusp losses are made up for with ~ 100MW of injection, the magnets might be heated by ~ 1 MW of ExB drift particles. Not trivial , but small compared to possible neutron exposure and Bremsstruhlung radiation heating.

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

D Tibbets
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Re: EMC2 has published a polywell preprint on arXiv

Postby D Tibbets » Sat Jun 14, 2014 10:50 pm

mattman, the images are confusing me, especially the last two. If the B field is excluded there would be no noticable spiraling motions of the charged particles inside the Wiffleball border- which I take to be the transition zone. The drawing of a B field line inside this zone seems innapropriate. In the last image, the motion tracks seem to be curving, again this would not occur like this if the B field is excluded.

The transition zone is an interesting region. Ideally this transition zone would be a line, and thus any charged particle reaching it from the inside would immediately bounce back (billiard table analogy). With some thickness though complex partial orbits and multiple orbits may occur due to collisional effects. How many of these particles (promarily electrons get knocked deeper into the B field where their gyro orbits are complete without traveling inward enough to again encounter the border region the mirroring , spiraling motions seem appropriate. What percentage of the electrons are in this region as a percentage of the total is uncertain, but I would think it would be best if it is kept small. The ions are not involved with this border provided they are introduced below the peak of the electron induced electrostatic potential well. Those upscattered ions that do reach the border will also rebound back and only the most upscattered ions would enter the full magnetic domain. It is these upscattered ions and mostly electrons that proceed with ExB drift, and eventually hit the magnet unless they manage to escape a cusp.

It occurs to me though that with their greater gyroradius they are less likely to be trapped. Once turned the potential well may pull them back below the border region. I'm guessing that ExB losses for ions is small, even for those upscattered ions. Most ExB losses may be from electrons. And as claimed, that amounts to only about 1% of electron losses (before recirculation I believe). As such the electron current from the border is ~ 1% of the cusp current (eg: 100 MW through the cusps is accompanied by 1 MW to the magnets via ExB). The stable region is not really stable, though it may be convenient to consider it so for comparative purposes.

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


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