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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mvanwink5
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Re: EMC2 has published a polywell preprint on arXiv

Postby mvanwink5 » Sun Jun 08, 2014 10:14 am

D Tibbets,
The central point of the research article was that the cusps do close at beta = 1 conditions, and that a potential well does form. Further, that the path to get to beta = 1 is by a start up procedure that jumps to that condition using hefty electron and ion injection (or other means). I think your point that the D-T example was to aid in comparison to other fusion efforts is correct and that it was not an engineering proposal. To get needed engineering data, WB-8 needs to be run as previously intended to get the data at beta = 1. I would suggest that start up of WB-8 solely by electron and ion gun injection might be assisted by another method and perhaps Park and team already have in mind what to do to achieve that. This report is definitely not the final research but a peer reviewed report to "get some real money" from properly supportive, serious about success, backers. The Navy appears to not fall into this category up to this point for whatever reason, and if my interpretation of the latest FPDS report is correct, this project is now considered complete as of 4-30-14.

So, this report proves polywell works and it is time to go to serious development mode, that the breakthrough needed for serious commitment is accomplished. Time to step it up, get some cash.

Maybe I am wrong here, but D-T has and always will have the first wall issue. General Fusion has an elegant real solution to that if they have the stable compression issue solved. Polywell's best hope is PB-11. This report keeps EMC2 in the trifecta 'Dark Horse' race, it is not a winning move, yet.
Near term, cheap, dark horse fusion hits the air waves, GF - TED, LM - Announcement. The race is on.

marvin57
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Re: EMC2 has published a polywell preprint on arXiv

Postby marvin57 » Sun Jun 08, 2014 10:48 am

mvanwink5 wrote:So, this report proves polywell works and it is time to go to serious development mode, that the breakthrough needed for serious commitment is accomplished. Time to step it up, get some cash.


Perhaps from the likes of Google? Finally?

Bill Gates? Elon Musk? Sir Richard Branson?

Some entrepreneur out there surely must have a bit of vision as well as some money with which to speculate.

TallDave
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Re: EMC2 has published a polywell preprint on arXiv

Postby TallDave » Sun Jun 08, 2014 1:46 pm

Tom Ligon wrote:...the conditions needed to instigate a proper wiffleball are apparently a bit steeper than first modeled, and it is quite helpful to have some data to tell just what it takes. Building a big machine and then trying to sneak up on a wiffleball from the bottom using inadequate equipment is a terrible waste of time and money.
That's a great point; remember, Bussard had some relatively expensive failures like HEPS and didn't really get what was he was after until WB-6. Until we hear otherwise, we should probably assume EMC2 is proceeding on a timeline that makes sense to them and the funders, given the risks and the unknowns.

As much money as people like Lerner have drawn in with promises of net power by 2010, the more circumspect approach achieves more credibility.
n*kBolt*Te = B**2/(2*mu0) and B^.25 loss scaling? Or not so much? Hopefully we'll know soon...

mvanwink5
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Re: EMC2 has published a polywell preprint on arXiv

Postby mvanwink5 » Sun Jun 08, 2014 2:02 pm

Money = Time. From day 1, Nebel, Park knew that they need large ion, electron guns, but couldn't get the support when the size needed to be much larger than the money they had. So, they went small as seen in this report.

Lerner had to go super cheap and virtually all his delays can be traced to that.

General Fusion is a good example of balancing risk, money, and development time. EMC2 and LPP, not so much.
Near term, cheap, dark horse fusion hits the air waves, GF - TED, LM - Announcement. The race is on.

mattman
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Re: EMC2 has published a polywell preprint on arXiv

Postby mattman » Sun Jun 08, 2014 4:31 pm

We have watched the polywell for many years, two questions have exist all that time:

1. Are the electrons in the center, non-thermal?
2. Does the electron cloud go diamagnetic?

If both were true, it would be huge. A non-thermal cloud means the Lawson criteria may not apply. (Gasp!) It also means Rider's criticisms may be less applicable. (Huge).

This publication partially answers the second question: electron diamagnetism.

They put a loop of wire into the plasma and measured the electron cloud exhibiting a real "extra" magnetic flux. This combined with an X-ray signal - detected from the cloud - was used to suggest the electrons have two modes: a low and high beta mode. In low beta, the confinement sucks. In high-beta, the electron cloud is diamagnetic, confinement Hell-a-rocks! The data suggests a clear switching between each.


Anyone know how a “Magnetic Flux Loop” works exactly?

mvanwink5
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Re: EMC2 has published a polywell preprint on arXiv

Postby mvanwink5 » Sun Jun 08, 2014 4:47 pm

As long as there is a potential well, which there was, electron distribution issue is satisfied.

Mag flux loop will yield a current depending on the integrated Mag field that penetrates it. (Ampere's law)
Last edited by mvanwink5 on Sun Jun 08, 2014 5:01 pm, edited 1 time in total.
Near term, cheap, dark horse fusion hits the air waves, GF - TED, LM - Announcement. The race is on.

dnavas
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Re: EMC2 has published a polywell preprint on arXiv

Postby dnavas » Sun Jun 08, 2014 4:59 pm

D Tibbets wrote:Note that this performance / breakeven is ~ 10 times worse than projected for WB100. What is different? That is hard to say as no numbers were provided about confinement, recirculation, confluence, etc.


The way I read it, there was no recirculation. Lifetime of 300 bounce confinement, and the profusion of measuring devices along the cusps make me think that recirculation wasn't being attempted. That would affect the numbers by a factor of ~10. That said, high B remained for about an order of magnitude more than 7ns * 300 bounces would predict, so I'm not sure what to conclude from that. Also, 300 is far lower than reported previously (1k and 10k?) and it's not clear why that is either.

If I'm viewing the videos correctly, it looks like highest losses are out of the faces, and I thought recirculation was less certain for such losses?

Corrections welcome -- it's been a long time, and I'm no physicist....

DeltaV
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Re: EMC2 has published a polywell preprint on arXiv

Postby DeltaV » Sun Jun 08, 2014 5:27 pm

From the photo in the paper, the vacuum chamber used seems too small if electron recirculation was being attempted. Same for the box extents in the sim movies.

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

Postby D Tibbets » Sun Jun 08, 2014 8:21 pm

The Wiffleball effect is not feeble in this machine relative to WB6. I guesstimate that it is about the same. Improvement from the cusp confinement of 7 passes to 300 passes. That is a little more than a 40 fold improvement. If you take the numbers from WB6 the improvement was ~ 60 passes to several thousand passes, again about a 40X improvement. The improvement is relatively the same. Of course the accuracy of WB6 results are now in question. I have some ideas that might resolve the issue but may also be foolish.

The apparently dismal cusp confinement in this machine has two contributors that I can speculate on. First- have you noticed the magnet separation? It is huge relative to WB6. It goes from a few mm to ~ 23 mm (as measured from the picture). I wonder if this greater separation is necessary to control ExB losses in the cusp at these increased densities. Conversely the temperature is possibly less and the B field is greater in this machine, so how to calculate the balance? This increased spacing in the corner cusp may make them more leaky. I have operated with the assumption that in WB6 the corner cusps had less leakage than the face centered cusp. Comments in the patent application suggests this. Here Parks implies ~ equivalence in the losses between the types of cusps. At least this is suggested by his use of all cusp losses being equal in his calculation for a D-T fusing reactor. Note that this machine is ~ 1/2 the diameter of WB6, and this means the surface area is ~ 1/4. Applying this to the same spacing in the larger machine the relative surface area of the corner cusps relative to the total surface area would decrease and thus the confinement would improve perhaps by as much as the change in relative seperation / total magnet diameter ^2. This could significantly improve confinement , thoug the face centered point cusps would also be changing in the opposite direction ammumeing constant B field strength at the magnet can surface. The sum would possibly be some improvement, though not great. But, hay improvement from 7 passes to only 10 or 15 or more passes is significant.

The second contribution to the relatively poor cusp confinement in this machine is the penetration of the interior by two humongous (well, large) coaxial cables used for measuring the B field strength inside. I am too lazy and uncertain about the exposed length to calculate the exposed surface area, but I suspect it may greater loss areas than even the most exposed nubs. Bussard always harped about the need to limit exposed surface area to less tha 1/10,000 of the total surface area represented by the facing magnet surfaces.
How much charged particles were intercepted by these cables, even how much the cables penetrated inside the Wiffleball border is uncertain, but I will assume these cables resulted in an arbitrary halfing of the confinement time.

Using these two modifiers, the cusp confinement might be massaged to levels closer to those claimed for WB6. Using the r^3 /r^2 scaling, just going to 30 cm would result in 2^3/ 2^2 or 8/4 or twice the confinement time in terms of passes. And each pass would take twice as long, so things add up quicky.

Seven pass confinement in this machine was due to design and the priorities for certain instrumentation. It is a compromised and dirty machine (all sorts of carbon and tungston ions), but this was purposely chosen and served the purpose of Wiffleball confirmation. As such this machine may not serve as a good basis for scaling. And I have no idea what baseline paremeters Parks based his scaling on.

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 » Sun Jun 08, 2014 8:44 pm

I am confident that the Polywell is not a candidate for a working D-T exclusive reactor. The neutron bombardment is to fierce and critically the first wall tritium production is severely compromised by the presence of the internal magnets and cusps.
But, D-D has much less neutron intensity and energy. It is more survivable. The question is if the reduced cross section and lower energy yield per reaction is enough to over come losses, including bremsstruhlung. In this regard I think D-D is easier than P-B11, and perhaps equivalent to D-He3.

Then there is the proposed D-D 1/2 catalyzed setup. There is 1 tritium and one He3 produced for each pair of D-D reactions. Here these more energetic fuels can be recycled and boost the yield from the basic D-D reactions. Especially the tritium. It can nearly triple the energy out for each D-D reaction. In a sense you can have your cake and eat it too. You have the problem of the fierce D-T neutron to handle, but you do not need to conserve it to produce more tritium. There is no need for a first wall absorber and all of the complexity that entails. You might utilize the neutron to make some more energy in say an external boron10 blanket, but no need to account for nearly every fusion neutron in order to maintain tritium against consumption in a dedicated D-T reactor like a tokamak. Even if the Polywell did grow to near tokamak size in order to achieve the same excess fusion power, the avoidance of the lithium first wall challenges (and the diverter?) may make a big difference in cost. The General Fusion approach is somewhat different as the lithium/lead first wall is an integral part of the reactor and has purposes other than just capturing neutrons and making tritium.

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

Stubby
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Re: EMC2 has published a polywell preprint on arXiv

Postby Stubby » Mon Jun 09, 2014 12:11 am

http://www.dailykos.com/story/2014/06/0 ... early-2006

word is spreading

mvanwink5 and tom quoted in blog

which one of you is Roger Fox? :lol:
Everything is bullshit unless proven otherwise. -A.C. Beddoe

CaptainBeowulf
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Re: EMC2 has published a polywell preprint on arXiv

Postby CaptainBeowulf » Mon Jun 09, 2014 1:09 am

It is indeed good to see some news. It must be around a year to a year and a half since I last posted here. I have lurked occasionally, but I haven't had anything to say about LENR etc.

The DailyKos article now says "Also republished by Climate Change SOS, Scitech, and DK Greenroots" at the bottom. So, word is spreading quickly.

Hopefully we will get to see some WB 7 and WB 8 based research papers with details over the next several months too, although I guess there is the possibility that all work relating to those two devices is proprietary to the Navy, and the Navy won't allow publication. Is anyone clear on whether this smaller device that proved the wiffleball effect was definitely part of the Navy contract, or could it have been something they put together after finishing work for the Navy on WB 8?

Also, what do people think of Roger Fox's analysis that WB-8 could have proven the wiffleball but needed bigger E-guns which the navy wouldn't fund? He seems to think that they had to go to this smaller device in order to have the ratio of E-gun power to machine size that they needed. I can see how such a narrative could be pieced together from some of the news threads including this one and "Recovery.Gov Project Tracker," but is it really a verified narrative or is it a conjecture?

Hopefully word spreads in the right directions (whether private or public sector) and EMC2 gets some real funding...

tauntaun_rider
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Re: EMC2 has published a polywell preprint on arXiv

Postby tauntaun_rider » Mon Jun 09, 2014 3:33 am

CaptainBeowulf wrote:Roger Fox [...] seems to think that they had to go to this smaller device in order to have the ratio of E-gun power to machine size that they needed....

The E-gun power in the smaller device is miniscule compared to the plasma sources. It works like a diagnostic, only providing enough high-energy electrons to demonstrate the wiffleball. There's no evidence that it has any effect on the potential well or the main plasma population.

mattman
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Re: EMC2 has published a polywell preprint on arXiv

Postby mattman » Mon Jun 09, 2014 3:47 am

Hello,

What I want to see is an energy distribution. I can tell you right now research is going to take flack for that.

Especially from ICF and Tokamak experts defending their funding.

===

Electrons go in at 7 KeV, on a beam, fine.

But if they bounce around 300 times... there are electron-electron interactions, electron-ion, magnetic field deflections, ect...

The energy distribution is going to start moving towards a bell curve via a Wiener process, like this:


Image


Explain to me how this process not happening?

Robthebob
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Re: EMC2 has published a polywell preprint on arXiv

Postby Robthebob » Mon Jun 09, 2014 5:45 am

hello folks, has everyone calmed down?
Throwing my life away for this whole Fusion mess.


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