Polywell: "Final nail?"

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

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Carl White
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Polywell: "Final nail?"

Post by Carl White »

Wikipedia has this section in its web page concerning polywell fusion now:
In June 2019, the results of long-running experiments at the University of Sydney (USyd) were published in PhD thesis form by Richard Bowden-Reid. Using an experimental machine built at the University, the team probed the formation of the virtual electrodes.[102]

Their work demonstrated that little or no trace of virtual electrode formation could be found. This left a mystery; both their machine and previous experiments showed clear and consistent evidence of the formation of a potential well that was trapping ions, which was previously ascribed to the formation of the electrodes. Exploring this problem, Bowden-Reid developed new field equations for the device that explained the potential well without electrode formation, and demonstrated that this matched both their results and those of previous experiments.[102]

Further, exploring the overall mechanism of the virtual electrode concept demonstrated that its interactions with the ions and itself would make it "leak" at a furious rate. Assuming plasma densities and energies required for net energy production, it was calculated that new electrons would have to be supplied at a rate of 200,000 Amps. This is essentially unfeasible.[102]

The paper sums up the results this way:

Initial results indicate negligible charge trapping with little to no potential well formation. Further, it is shown that the existence of potential wells reported in previous publications can be explained without the requirement of a virtual cathode produced by trapped electrons. Moreover, it is shown that potential wells, which produce electron confinement and heating from virtual cathodes, no longer exist with increasing plasma density.[102]

The results were so convincing that it has been described as a "final nail in the coffin for polywells."[103] However, Bowden-Reid's research admitted that it had little insight into what EMC2's research and development program entailed due to the lack of published articles and intellectual property restrictions, recommended upgrades to the SDyd machine, and concluded by stating, "Continued development of MCVC-0 is required in order to properly rule out the possibility of charge induced potential well formation. Owing to the poor confinement properties of the biconic cusp when compared with the Polywell configuration, it is possible that the observed behaviour is an artefact of insufficient electron injection current... It is hoped that the above upgrades will result in a machine that is capable of generating measurable deuterium-deuterium fusion".[102]:149

EMC2's last known publication was on the discovery of an electron gyroradius scale current layer and its relevance to magnetic fusion energy, the Earth's magnetosphere, and sunspots.[104]
102. Bowden-Reid, Richard (7 June 2019). An Experimental Study of Gridded and Virtual Cathode Inertial Electrostatic Confinement Fusion Systems (Technical report). University of Sydney.

103. "Is the polywell fusion approach still under active development anywhere?". I spoke to Joe Khachan (head of the USyd lab) about the results and he described the results as a "final nail in the coffin for polywells.

104. Park, Jaeyoung; Lapenta, Giovanni; Gonzalez-Herrero, Diego; Krall, Nicholas A. (2019-12-13). "Discovery of an Electron Gyroradius Scale Current Layer: Its Relevance to Magnetic Fusion Energy, Earth's Magnetosphere, and Sunspots". Frontiers in Astronomy and Space Sciences. 6: 74. arXiv:1901.08041. Bibcode:2019FrASS...6...74P. doi:10.3389/fspas.2019.00074. ISSN 2296-987X. S2CID 119411012.

Giorgio
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Re: Polywell: "Final nail?"

Post by Giorgio »

I would say no.

The experimental apparatus is different from a Polywell machine and the power and energy configurations are also order of magnitude smaller.

The conclusions and explanation on why he didn't measure a potential well with this apparatus are indeed interesting.
Interesting also the derived physic model that could reproduce the published results of the previous WB6-mini results.
That said, the design of this machine is so different that applying the observed results to a Polywell is just meaningless.

Let me make you an example.
Me an you are observing a volume of water waiting for ripples to appear over it.
I observe a volume of water sealed into a plastic transparent container rigidly fixed on the ground.
You observe a dish filled of water, open from the top and standing on ground over a seismic insulation base.

When it rains you observe ripples, I do not.
When there is a small quake I observe ripples you do not.
Both of us will be convinced that there must have have been an error in the observation of the other, while in truth we are both right.

His observations are interesting and worth to keep in mind for future Polywell experimenters, but his results do not add (nor subtract) any new piece to the Polywell puzzle.
A society of dogmas is a dead society.

choff
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Re: Polywell: "Final nail?"

Post by choff »

If it's the final nail in the coffin for the Polywell, is it also the final nail for Lockheed Martins experiment, they have a lot in common. Did the paper also look at the results from the last EMC2 WB-X device?
CHoff

paperburn1
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Re: Polywell: "Final nail?"

Post by paperburn1 »

I am not a nuclear physicist, but play one on the internet.

Giorgio
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Re: Polywell: "Final nail?"

Post by Giorgio »

choff wrote:
Sat Jan 23, 2021 12:24 am
If it's the final nail in the coffin for the Polywell, is it also the final nail for Lockheed Martins experiment, they have a lot in common. Did the paper also look at the results from the last EMC2 WB-X device?
The test apparatus of the paper was just two magnetic coil rings parallel to each other, run at voltages between 0,5KV and 6Kv and with an electron beam of 0,15A.......
Applying this paper findings to a Polywell hexahedral configuration running at higher values has really little scientific meaning.

I have to wonder if the people involved in defining this as a "final nail" actually took care of reading the paper in its fullness and understood what the results are all about, or they simply extrapolated some phrase out of general context.
A society of dogmas is a dead society.

Giorgio
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Re: Polywell: "Final nail?"

Post by Giorgio »

I went to quickly read it back to refresh my memory.

Here is the paper for everyone to read:
https://ses.library.usyd.edu.au/bitstre ... sAllowed=y
The Apparatus description and experimental runs start from page 53

And here is a passage of the last paragraph of the conclusion of the research:
"Owing to the poor confinement properties of the biconic cusp when compared with the Polywell configuration, it is possible that the observed behaviour is an artefact of insufficient electron injection current. High rates of electron loss through the large equatorial line cusp prevents the trapping of an excess electron population and hence the formation of a virtual cathode."


Quite a blunt "final nail"..... :roll:
A society of dogmas is a dead society.

RERT
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Re: Polywell: "Final nail?"

Post by RERT »

Edits could be proposed for the Wikipedia page...

Giorgio
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Re: Polywell: "Final nail?"

Post by Giorgio »

RERT wrote:
Mon Jan 25, 2021 10:22 pm
Edits could be proposed for the Wikipedia page...
Indeed, but I have no idea how the procedure works.
If someone knows how to do it than changes should be done as that section is highly misleading.
A society of dogmas is a dead society.

RERT
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Re: Polywell: "Final nail?"

Post by RERT »

Anybody can sign up to be a wikipedia editor.

Once done, go to the ‘talk’ page, propose an edit. Best be unemotional and quote some authority figure from a ‘reliable source’ publication. Monitor responses, and in due course make the edit or a version modified by comments received. Not hard unless there are other editors with an axe to grind.

Polywell isn’t a topic where you will get armies of insane trolls censoring posts - at least i don’t think so! On the other hand, there may be a ‘fusion-is-impossible-we-need-fewer-people’ bunch if crazies out there...

kunkmiester
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Re: Polywell: "Final nail?"

Post by kunkmiester »

This is the one I posted about a while back. It didn't look like it was as conclusive as the authors thought, but I didn't get any answers then.
Evil is evil, no matter how small

daveklingler
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Re: Polywell: "Final nail?"

Post by daveklingler »

I just noticed that the intro to the Wikipedia article says that research was conducted between the 1960's and 2019. My memory is that Bussard had the idea well before he retired, but didn't actually start researching it until he formed EMC. Of course, I can't refer to Wikipedia any more to check.

Where's MSimon?

choff
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Re: Polywell: "Final nail?"

Post by choff »

Did a little internet search on Polywell for the first time in a while and noticed this publication. It talks about Diocotron Pumping to remove cold electrons. Has this been covered before?

https://www.researchgate.net/publicatio ... Generation
CHoff

choff
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Re: Polywell: "Final nail?"

Post by choff »

The article talks a lot about computer simulation with an ITER sized Polywell reactor, 75 meter outer wall running PB11 steady state having Pout/Pin at 0.13, and how only a slight scale up would make it over unity.
CHoff

ltgbrown
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Re: Polywell: "Final nail?"

Post by ltgbrown »

Isn't this from Feb 2018?
Famous last words, "Hey, watch this!"

choff
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Re: Polywell: "Final nail?"

Post by choff »

Yeah, but I did a quick search on T-P and didn't see anything about it. Maybe it was discussed, maybe not, been so long.
CHoff

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