Where's the beef?

Discuss how polywell fusion works; share theoretical questions and answers.

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kresobilan
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Post by kresobilan »

Even if WB-7 experiment data indicate a success, science shall be called in. The pace of improvement of the device depends also on theoretically understanding processes in the device. We don't have the time of the blind watchmaker. Many thanks to Mr. Carlson for the effort, I think it is not in vain.
Kind Regards,
Kreso

tonybarry
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Post by tonybarry »

Art Carlson wrote:This one floored me. I was worried about whether there was published data on the scaling of confinement time with density, and then I discover that Bussard didn't even measure the density. No interferometry. No Langmuir probes. No spectroscopic methods. No Thomson scattering. Just the assumption of pressure balance and beta equals one. And even that he gets by making a scan of coil current and taking the peak of the photomultiplier signal. That takes real courage.
The lack of experimental rigor in these tests is a serious concern. Which is why we await further experimental results. In your original post t Talk-Polywell you wrote:-
Art Carlson wrote:If I can, I will uncover the soft underbelly of the polywell concept and eviscerate it. Then you will all thank me kindly for stopping your waste of time, and we will all move on. If, on the other hand, you are able to convince me using solid physics that the polywell has a real potential, I will meekly withdraw my arrogance and claim that I said that all along.
I think that many of us replied to your post agreeing with your intent, and to my knowledge, little has changed. You are thankfully aware of the limitations of our present state of understanding (both theoretical and experimental). If polywell succeeds as a practical device it will be because those constructing it worked within the laws of physics and engineering. To understand those laws is still what we are about.

Regards,
Tony Barry

scareduck
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Post by scareduck »

I'm not sure what you're hoping for here, Art. The only person here who has any idea of what is happening with WB-7 and has access to the data is Rick Nebel. The rest of us are largely guessing.

TallDave
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Post by TallDave »

From these eight counts you are not only deducing the quality of confinement in a small scale device
Hmmmm, no. Remember, WB trapping was not just discovered in WB-6. It goes all the way back to SCIFE and includes the intermediate machines. The counts are only one piece of evidence.
you are seeing the confirmation of scaling laws that must sustain you over seven orders of magnitude
Definitely not; the power scaling laws didn't come from the machine and most of us are actually quite worried about both the power and gain scaling, from an engineering standpoint as well as physics. But we haven't yet heard any good arguments why we shouldn't build a machine to find out if they work.

Most of us are of the opinion that with $20B slated for ITER, $2M was a reasonable sum to find out if Bussard had anything with WB-6. If WB-7 appears to show WB trapping, ion focus, and fusion counts like those Bussard reported, then given the huge payoff it's probably worth $100M or so to find out if it scales.

Roger
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Post by Roger »

TallDave, maybe only 20 to 50 mill for a 160cm device.

Actually proof of scaling can come far cheaper, WB-6 has 30cm coils, build one double the size, 70cm, and we should hope to see 128x the output. I think that might be done for 3-5 million. Easy.
I like the p-B11 resonance peak at 50 KV acceleration. In2 years we'll know.

dnavas
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Post by dnavas »

Roger wrote:TallDave, maybe only 20 to 50 mill for a 160cm device.

Actually proof of scaling can come far cheaper, WB-6 has 30cm coils, build one double the size, 70cm, and we should hope to see 128x the output. I think that might be done for 3-5 million. Easy.
Scaling is not the only concern, though, surely? pB11? And the expensive killer, continuous operation, which requires active cooling.... Would smaller machines be capable of those investigations?

If a cheap scaling test is all you're after, why not make the device 15% bigger and go for your first double?

-Dave

Scupperer
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Post by Scupperer »

dnavas wrote:If a cheap scaling test is all you're after, why not make the device 15% bigger and go for your first double?
Why not make it smaller? It'd be quicker and cheaper than the current WB-7 device, and it would achieve the same objective; assuming that a smaller device would still give distinctly measurable results.

Make a dodecahedron version, too, and compare.

Is there any point in going larger unless you're going to start tackling the engineering, design and materials problems?
Perrin Ehlinger

rcain
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Post by rcain »

Hi Dr Carlson

I just loved your 'eviscerative' salvo - and sardonic to boot!) - I'm sure Dr Bussard would be truly gutted - were he with us.

I'd really love to take you on concerning your 'electrons taking two paths at once' concept - alas, I think my both my maths and physics will fall woefully short, but I'm trying to get hold of a copy of the paper in any case - just in case I should feel 'so bold and audacious'.

Your 'observation' really does deserve a proper response, I feel, by someone properly qualified - I find it hard to believe that such an arithmetic blunder should have been overlooked for so long by so many.

on other points::

Your quote regarding - 'line cusps' is this referring to containment in the absence of the Wiffle Ball inflation effect (difficult to guess out of context, I'm afraid I don't yet have access to the paper)?

Supposing you didn't have access to Langmuir probes, spectroscopic methods, or Thomson scattering (and I am supposing Bussard didn't, else he would have utilized them), how best would you have estimated core density and confinement?

More generally, and this particular experiment aside, and even notwithstanding particulars of the WB Polywell/magrid configuration - would you not agree that IEC devices such as the Farnsworth–Hirsch Fusor represent a very good starting point to embark upon engineering design of fusion systems - given their propensity to produce neutrons in abundance.

(if not, how else would you approach the problem - note: in this example you do not have 10Bn$ of public money to throw at it).

seeking enlightenment...

TallDave
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Post by TallDave »

Re scaling and building a slightly larger machine:

Sure, you could, but keep in mind the scaling laws don't need to be proven (they're basic physics), just whether the various Polywell components are disrupted by known and unknown effects on the way from milliwatts to megawatts. A machine in the 1-watt range would not tell us much, and would take another couple years and a lot of money to build and test.
TallDave, maybe only 20 to 50 mill for a 160cm device.
To build it, yes. To get it to work, Bussard's 150M figure is probably more accurate.
Last edited by TallDave on Mon Jul 07, 2008 3:25 pm, edited 1 time in total.

Art Carlson
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Post by Art Carlson »

rcain wrote:Your quote regarding - 'line cusps' is this referring to containment in the absence of the Wiffle Ball inflation effect (difficult to guess out of context, I'm afraid I don't yet have access to the paper)?
.
Unless I misunderstood something, this is after going to high beta (= whiffle ball made).
Supposing you didn't have access to Langmuir probes, spectroscopic methods, or Thomson scattering (and I am supposing Bussard didn't, else he would have utilized them), how best would you have estimated core density and confinement?
I would cut corners someplace else rather than flying blind. A density diagnostic is a sine qua non, and these diagnostics are not that difficult or expensive, especially Langmuir probes.
More generally, and this particular experiment aside, and even notwithstanding particulars of the WB Polywell/magrid configuration - would you not agree that IEC devices such as the Farnsworth–Hirsch Fusor represent a very good starting point to embark upon engineering design of fusion systems - given their propensity to produce neutrons in abundance.

(if not, how else would you approach the problem - note: in this example you do not have 10Bn$ of public money to throw at it).
Fusion is easy. Just point a deuterium beam at a block of heavy parafin. But it's easy to show that this method, despite production of copious neutrons, can never produce net energy. It's the same with the Polywell and other IEC devices. Develop them for neutron sources. They're good at that. But forget about making power from them.

My personal favorite longshot for fusion energy is the Field-Reversed Configuration.

Munchausen
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Ecclesiastes 7

Post by Munchausen »



Ecclesiastes 7

3Sorrow is better than laughter: for by the sadness of the countenance the heart is made better.

4The heart of the wise is in the house of mourning; but the heart of fools is in the house of mirth.

5It is better to hear the rebuke of the wise, than for a man to hear the song of fools.
I have been following the Polywell internet debacle for about a year now. I have seen quote a lot of scepticism from those knowledgeable in this area but somehow I made the conclusion that it is hard to prove or disprove the Polywell without experiments. The WB-7 seemed to be a cheap and funny thing to try. So I joined in and signed the online petition for funding to the house of congress.

I must say dr. Carlson has done a better job in explaining his scepticism than the others in his guild. Perhabs I would not have signed that petition if he had joined the discussion earlier.

Perhabs the major lesson to be learned from the WB-7 will be that allocation of research funds should be done by schooled professionals.

By the way: Lets assume that the WB-7 will conclusively prove that this idea is wrong, no potential well, no neutrons, nothing whatsoever. Is that a result that may be published? Or will it all end with an anonymous report in an archive somewhere?

rcain
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Post by rcain »

Art Carlson wrote:
rcain wrote:Your quote regarding - 'line cusps' is this referring to containment in the absence of the Wiffle Ball inflation effect (difficult to guess out of context, I'm afraid I don't yet have access to the paper)?
.
Unless I misunderstood something, this is after going to high beta (= whiffle ball made).
Supposing you didn't have access to Langmuir probes, spectroscopic methods, or Thomson scattering (and I am supposing Bussard didn't, else he would have utilized them), how best would you have estimated core density and confinement?
I would cut corners someplace else rather than flying blind. A density diagnostic is a sine qua non, and these diagnostics are not that difficult or expensive, especially Langmuir probes.
More generally, and this particular experiment aside, and even notwithstanding particulars of the WB Polywell/magrid configuration - would you not agree that IEC devices such as the Farnsworth–Hirsch Fusor represent a very good starting point to embark upon engineering design of fusion systems - given their propensity to produce neutrons in abundance.

(if not, how else would you approach the problem - note: in this example you do not have 10Bn$ of public money to throw at it).
Fusion is easy. Just point a deuterium beam at a block of heavy parafin. But it's easy to show that this method, despite production of copious neutrons, can never produce net energy. It's the same with the Polywell and other IEC devices. Develop them for neutron sources. They're good at that. But forget about making power from them.

My personal favorite longshot for fusion energy is the Field-Reversed Configuration.
Just point a deuterium beam at a block of heavy parafin
- alas, it appears someone has already attempted to patent this method :)


Field Reversed Configuration - you mean something like these guys are working with -

A High Density Field Reversed Configuration Plasma for Magnetized Target Fusion - Intrator, Park and co - http://fusionenergy.lanl.gov/Documents/ ... tor03f.pdf - vis:

'...Significant progress towards a target plasma
has been achieved, with FRC parameters within a factor of 2-3
of the design goals.....'

sounds promising - so long as you don't mind changing the imploding Aluminium liners a few thousand times a second.

So you are suggesting that 'theoretically' IEC per se can't work at Q>1 (though contrary theories still abound it seems)?

I'd love to see experiment prove you wrong of course, though I feel we would somehow be cheated of a victory if we couldn't provide a conclusive and convincing theoretical model ahead of any real positive outcome.

Maybe I'm just stuck on Bussards quote - '...the heavens are filled with billions of fusion reactors, and not one of them is toroidal...' - (nor cylindrical i think). Hence its hard to shake a gut belief/hope that 1/r^2 has got to have some intrinsic usefulness in our endeavor.

Can you point me to any more up to date results/methods wrt FRC?

with thanks ...

seedload
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Re: Ecclesiastes 7

Post by seedload »

Munchausen wrote:Perhabs the major lesson to be learned from the WB-7 will be that allocation of research funds should be done by schooled professionals.
Wow. You talk like no "schooled professionals" have ever looked at this concept. You talk like the Navy just throws money at any silly idea that comes their way without constantly reviewing the ideas and the progress. You speak as if Dr Bussard and Dr Nebel have no schooling and are just making it up. Seriously, you need to step back and think. Dr. Carlson is talking about issues that he sees with the design which is always good because it creates opportunities for debate, but it isn't in and of itself a reason to stop funding. I am not even sure that he would object to the program at its current level of insignificant funding regardless of his opinion of its chances of success.

Besides, schooled professionals often get stuff funded at extreme levels creating teaming masses of new schooled professionals to perpetuate the funding of more of the same stuff at exponentially greater extreme levels resulting in the drying up of funding for dissenting schooled professionals. ITER and Global Warming being two in our face examples.

jmc
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Post by jmc »

Actually there's quite alot of published skepticism from people who have undergone a significant quantity of effort to show that the Polywell wouldn't work the way Bussard claimed it would (Rider, Nevins, Dolan).

I've done a fair amount of reading through Bussards reports and papers and I've seen a lot of dodgy stuff and one slip which was obvious even to me. (Where if you read it carefully you realised that he implicitly assumes ions only collide in the core). So that he could make a mistake in a report that few physicists have read that written with unclearly typed maths is not surprising.

100 million pounds is far too much to invest in an unproven concept unless its well diagnosed and tested so that the scaling laws are verified to a reasonable degree of certainty.

Still, the fact that it can achieve beta=1 means it merits further investigation at a low level until it can be understood. Even Dr. Carlson was surprised by Carter's plot of electron trajectories. I don't agree with killing harmless low level investigations into unexplained magnetic confinement regimes.

Munchausen
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Post by Munchausen »

I am not even sure that he would object to the program at its current level of insignificant funding regardless of his opinion of its chances of success.
Well, the money is gone no matter what Art Carlson say. We all had a nice time daydreaming and speculating about this and we are all interested in what comes out of it.

No use crying for spilled milk.

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