Talk-Polywell.org

The summary states this project's deliverable is a report. It appears that there is no hardware to deliver.

I still don't think that there is much hope of the current polywell work getting to the point of actually producing fusion [of provable beam-beam origin]. The whole term 'plasma scaling' of the current contract worries me - conventional plasma diagnostics should not work for polywell. In point of fact, using DD and measuring fusion output [by neutrometry] should actually be one of the best and unambiguous measures of particle behaviour in such a device, operating at the energy levels it should be.

What I am expecting in the report is some pre-ramble about the difficulties of measuring the properties of the thing, then a series of dubious assumptions about some measurement technique of 'Beta' and well-depth, then those measurement assumptions configured in such a way that makes beta look like it goes up with increasing B and E, according to a theory [which has also magically transformed into something more conservative than previous theories].

Whilst brushing aside the lack of neutron-counting and actual fusion measurements, it will conclude by saying that this 'beta scaling' proves a larger device will 'work', whilst the conclusion fails to direct any concern towards cusp or brems losses [dismissing their scaling as insignificant for larger devices] and also doesn't concern itself with what will actually happen to the physics of the thing if it actually does start producing significant fusion power [and all the high-current beam instabilities and reactor volume contaminations from the mega-amp ion currents that would be required].

What will then happen is that whosoever is driving this thing will manage to find a half-dozen or so independent physicist to say 'well, I suppose there could be something in this - after all, these results don't prove polywell doesn't work'. This, in turn, will be enough to convince a panel of government/military folks who make decisions based on what they are told [rather than know], it'll get funding for a bigger version, and it will get built.

Fusion would have to be done with this device. But the fusion it generates is weak and seemingly inconsequential. Folks will say 'gosh, there must be some physics here that we haven't quite understood, but, hey look at the two data points we have, this should extrapolate to real energy gains if only we make it bigger'.

&c.,

&c.,

...and therein lies the history of tokamak.

...Sorry, I meant polywell.....

.. or, it 'could' just work ...

.. or someone else will built something else, or maybe something similar, and it 'might' just work.. maybe beat EMC2-Navy to the prize and glory.

unless you believe nothing will work.

Why don't we just wait the report?

Well, that would be boring...

But, I am waiting regardless.

Giorgio wrote:Why don't we just wait the report?

Because eventually, delays become indicative evidence.

A report was promised as of yesterday at latest, and is now "delayed." At the least, the plausibility-meter should be twitching.

chrismb wrote: ....
Fusion would have to be done with this device. But the fusion it generates is weak and seemingly inconsequential. Folks will say 'gosh, there must be some physics here that we haven't quite understood, but, hey look at the two data points we have, this should extrapolate to real energy gains if only we make it bigger
......

That is a narrow viewpoint for the Polywell research WB6-8. As far as fusion output as evidenced by neutron counts WB6 is indeed very limited. Added to earlier results it allows for some uncertain predictions on scaling. But WB7 and 8 are much different. At least they presumably are- darn, where are those results!

WB 7 MAY have data from eg: ~ 500-1500 Gauss, voltages from ~5,000 to 20,000 volts, plus numerous other knob settings, plus at least two to three configurations (original, possible nub interconnect adjustments, ion guns). WB 8 MAY scale the B fields from ~ 500 to 8,000 Gauss, voltages from ~ 5,000 to ~ 80,000 volts if they got serious about comparing fusion to scattering rates and thermalization rates vs restoring effects.

So, within the ranges above they should have (or soon have) a broad range of size, B-field, and voltage scaling effects on properties and performance.
Admittedly, things could change at even larger scales, but the projections should be much more reliable than those available through WB7.

Mostly what you are saying is that, if they were interested in evaluating performance at full scale, they should have gone to full scale tests directly, and not temporized with this intermediate scale. Either that, or abandon the efforts entirely because they didn't know the answer. That you bemoan the spending of ~$10,000,000 for this level, makes me doubtful that you would have been in favor of going to a full scale testbed at ~ $200,000,000.

Personally, I would have liked to see a larger project, perhaps a 1 meter diameter or slightly larger machine, or a staggered parallel process. I admit they are doing this in a sense, at least from a planning aspect, as a scaled up machine design is part of the provisional part of the contract.

And, actually WB 8 may be a nice compromise size. Big and powerful enough to accommodate the required instrumentation and to give a sufficient scaling range to make predictions with an acceptable (note: not a 100%) level of confidence.
It also will apparently allow for testing and characterization of advanced fuels like P-B11, perhaps even more important if the recent alpha energy distribution claims are true (~ 2 x 4 MeV + 1 x 0.75 MeV alphas, instead of ~ 1 x 4 MeV + 2 x 2.4 MeV alphas).

Dan Tibbets

D Tibbets wrote:Mostly what you are saying is that, if they were interested in evaluating performance at full scale, they should have gone to full scale tests directly, and not temporized with this intermediate scale. Either that, or abandon the efforts entirely because they didn't know the answer. That you bemoan the spending of ~$10,000,000 for this level, makes me doubtful that you would have been in favor of going to a full scale testbed at ~ $200,000,000.

No, not at all. What I am saying is that I, and I expect most reading this, would want them to be pumping DD into it and be measuring neutrons. I would want to see a multi-dimentional scan of the variables and a plethora of different neutron detectors distributed isotropically around the kit, sufficient to demonstrate fusion - and lots of it - is happening at the centre, beam-beam wise. Like I say, I don't expect that. Just look at the way the summary words have been re-written.

I don't believe this project requires $10M to demonstrate fusion across a wide set of variables. Just look at what amateurs can do on a few thousand bucks. And what is one big concern for amateurs - why! measuring neutrons, of course!

I'll summarise my prediction - this project is going to show scarce few neutrons, just like earlier experiments. Better to show 'plasma behaviour' and milk the budgets, tokamak-like.

Just like Bob Hirsch said of US fusion research several decades ago - they've forgotten it's a project about doing fusion!!

You know for a fact that Park & co have forgotten that this is about doing fusion?

Betruger wrote:You know for a fact that Park & co have forgotten that this is about doing fusion?

Well, if the project summary goes from;

We expect to determine if the Polywell is suitable as a clean energy source for electrical generation.

to

We expect to determine if the plasma scaling agrees with the Theoretical models.

..dunno.. you tell me?

Besides, it's a bit like everything about this project has been conducted in a way that nothing is going to ever be 'known' about it.

chrismb wrote:I still don't think that there is much hope of the current polywell work getting to the point of actually producing fusion [of provable beam-beam origin]. The whole term 'plasma scaling' of the current contract worries me - conventional plasma diagnostics should not work for polywell. In point of fact, using DD and measuring fusion output [by neutrometry] should actually be one of the best and unambiguous measures of particle behaviour in such a device, operating at the energy levels it should be.

What plasma diagnostics are you thinking, and why do you think they won't work?

I do agree that neutrons from running deuterium would be a very useful diagnostic, especially if some degree of spacial resolution can be obtained.

As for a change in language from a direct question of whether the polywell is suited as a power generator to characterizing plasma scaling, the latter appears to be the largest uncertainty related to the former.

a direct question of whether the polywell is suited as a power generator to characterizing plasma scaling

In other words, if you prove scaling then you prove viability of
"Polywell ... as a clean energy source for electrical generation".

"Working as designed." Sounds like scaling is being proved.

From the past few posts, I agree that I would like to see the data and lots of it, Proving central converge4nce and focused beam beam fusion would be nice, although according to Nebel it is not absolutly nessisary for D-D fusion.
Also, beam beam fusion is, I believe, implicit in the scaling law predictions. Neutron counts isotropically should easily see this.
As far as costs there is a very large gap between a ~ 6 inch vacuum chamber and a few dozen milliamps of current (perhaps adding up to ~ 1 kilowatt power input. And a ~ 1.5 meter vacuum chamber, lots of expensive equipment, very powerful power supplies well in excess of Magawatts, if they push the drive voltage any. Add to that the business costs of a small company, etc, and I think $10,000,000 over a two year period is a bargin.
I suspect EMC2 is borrowing, stealing and begging for equipment, and if not the costs would be significantly higher.

I also suspect that the loss scaling is one of the most important aspects of WB8 testing. WB 7 may have given confident data on other questions.

Dan Tibbets

djolds1 wrote:

Giorgio wrote:Why don't we just wait the report?

Because eventually, delays become indicative evidence.
A report was promised as of yesterday at latest, and is now "delayed." At the least, the plausibility-meter should be twitching.

You do have a point about the plausibility-meter twitching, especially when you discover changes in the "project summary".
Still, only on reading the report we will clarify these points.

hanelyp wrote:As for a change in language from a direct question of whether the polywell is suited as a power generator to characterizing plasma scaling, the latter appears to be the largest uncertainty related to the former.

Chris main issue is that you should not have any type of change in language in an awarded contract, and I do agree with him on this.
Plus the "power generation" part already includes the "characterization of plasma" as a fundamental step (you can't get to power generation without having fully understood the way the plasma inside a Polywell behaves). By chancing the language the way they did they are actually reducing the scope of their work and not simply defining it in a different way.

An extra post in 'theory', just made.

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