Modeling Polywell

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

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Art Carlson
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Post by Art Carlson »

Well, Rick saw something happen that he interpreted as formation of a WB. He has never told us exactly what his definition of WB physics is, nor the chain of logic he used to draw his conclusion. Thus there are considerable uncertainties involved in interpreting Rick's statement, even if we accept his integrity. But hey, it's plenty if all you want to do is speculate. I guess your choice of words - "we know it happens" - triggered a red flag.

TallDave
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Post by TallDave »

Heh. Fair enough.

How about "we know something happens that Rick says looks like WB confinement (as did Bussard), which Joel has been trying to model without much success yet"?
n*kBolt*Te = B**2/(2*mu0) and B^.25 loss scaling? Or not so much? Hopefully we'll know soon...

icarus
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Post by icarus »

we know something happens that Rick says looks like WB confinement (as did Bussard)
No basis from which to theorise, model and contribute, even to those of us with the best of intentions (including helping humanity), eh?

Science with the big "S" is sceptical.

MSimon
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Post by MSimon »

icarus wrote:
we know something happens that Rick says looks like WB confinement (as did Bussard)
No basis from which to theorise, model and contribute, even to those of us with the best of intentions (including helping humanity), eh?

Science with the big "S" is sceptical.
An excess of scepticism can hurt too. i.e. Cold Fusion.
Engineering is the art of making what you want from what you can get at a profit.

icarus
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Post by icarus »

Sceptism should be roughly inversely proportional to the amount of data available?

MSimon
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Post by MSimon »

icarus wrote:Sceptism should be roughly inversely proportional to the amount of data available?
Cold Fusion.

I'm not saying all scepticism is unwarranted. Just that from time to time strange stuff turns up.
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TallDave
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Post by TallDave »

Skepticism in the practice of science is desirable (as opposed to belief in Science as a special kind of received wisdom or argument from authority; e.g. "we should accept proposition X as fact because most scientists agree with proposition X"). If Rick just accepted everything Bussard said without testing his claims in WB-7, that would be bad science, and policy based on that notion would be bad policy, as would funding WB-8 without reviewing Rick's assertions.

Fortunately I'm not doing any science or policy, I'm only trying to assign possibilities the likelihoods that seem most appropriate, so as to have a discussion of what's probably going on over at EMC2. I am more than willing to stipulate that all Rick's claims should only be treated as true arguendo, and should be thoroughly reviewed and re-tested whenever that is possible.
n*kBolt*Te = B**2/(2*mu0) and B^.25 loss scaling? Or not so much? Hopefully we'll know soon...

rcain
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Post by rcain »

to Wiffle-ball modelling...

has anyone th faintest idea how this can be happening (theoreticallly)..

what are the major dimensions (quantities/measures) of the structure?

i'm imagining something using differential ion veloicities about the core, then exploring it by sending a simulated 'impulse' to the magrid (or injector current, other variable...), to see how it responds. seems to me a micro-model of a 'few' charged particles (rather than 'macro') is where we ought to be starting.

you might have thought Ricks POPS work, the theory at least, ought to predict something like WB formation/formulation.

does anyone understand this mechanism?

TallDave
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Post by TallDave »

has anyone th faintest idea how this can be happening (theoreticallly)..
The Valencia paper seems to argue the deformation of the magnetic fields in response to the electron pressure produces the effect (by squeezing the cusps closed).

quoth Rick:
Here’s what we know and what we don’t know:

1. We don’t have the spatial resolution of the density to see if the cusps are quasi-neutral on the WB-7
2. In one-D simulations the plasma edge (which corresponds to the cusp regions) is not quasi-neutral. Therefore, if the cusps are quasi-neutral it must be a multidimensional effect.
3. Energy confinement on the WB-7 exceeds the classical predictions (wiffleball based on the electron gyro-radius) by a large factor.
Our conclusion is that both the wiffleball and the cusp recycle are working at a reasonable level.
POPS isn't really related, afaict, as WB is a Polywell-specific phenomenon.
n*kBolt*Te = B**2/(2*mu0) and B^.25 loss scaling? Or not so much? Hopefully we'll know soon...

MSimon
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Post by MSimon »

It is my opinion that oscillation is a POPS related phenomenon.
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KitemanSA
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Post by KitemanSA »

MSimon wrote:It is my opinion that oscillation is a POPS related phenomenon.
Probably so, but that isn't "recirculation".

It would be interesting to see if they had any indication of periodicity in electron flow in WB7.

Dr. N. :?:

MSimon
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Post by MSimon »

Probably so, but that isn't "recirculation
Yes. And it will have a preferred frequency. I wrote up something called LC POPS where I proposed enhancing the natural frequency with an LC circuit in the DC feed.
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rcain
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Post by rcain »

TallDave wrote:The Valencia paper seems to argue the deformation of the magnetic fields in response to the electron pressure produces the effect (by squeezing the cusps closed).
Hi Dave - yes I've read that several times, but as i recall it doesnt dwell on the mechanism, just plows forward with some numbers, showing that if one did exist, it might(should?) be consitent with the desired trapping effect.

that it seems to me was perhaps the easiest bit to show (smaller holes, less leakage isnt that hard a concept to sell).

i was more interested in emergence of the the diamagnetic phenomenon we are supposing to be the WB. afaik, even the mighty Indrek's models 'supposed that', if a WB existed, its effects might be approximated as a 'concentric' mirror polywell - but that is just short circuiting the analysis, to get to some usable simu-data (i think).

though i could be wrong. maybe Indrek's already thought a great deal about the (PIC) internals of WB formation.
quoth Rick:
Here’s what we know and what we don’t know:
1. We don’t have the spatial resolution of the density to see if the cusps are quasi-neutral on the WB-7
why not? if its important, surely we aquire some resolution.

seems to me also that much can be determined from even moderate spatial resolution. - Ive seen LIF and Doppler being used in a couple of papers from IEC 2009. (Nice summary of possible techniques - here http://www.answers.com/topic/plasma-diagnostic ).

so, i dont see how that is holding us back here.
2. In one-D simulations the plasma edge (which corresponds to the cusp regions) is not quasi-neutral. Therefore, if the cusps are quasi-neutral it must be a multidimensional effect.
but the cusps and the plasma edge are connected, no? they form a discernable common structure. but with further internal discontinuities. so, 'multidimensional' yes, though theres not a great deal here that isnt, surely.

'WB' then, may be the most important metric 'coupling' in the system, so it would certainly be nice to see ut set it down in even a rudimentary dimensional formulation, that could be agreed on.

and some real experimental numbers, obviously
3. Energy confinement on the WB-7 exceeds the classical predictions (wiffleball based on the electron gyro-radius) by a large factor.
...hang on a sec. shouldn't those classical predictions have given you the correct result? theres nothing non-classical going on, surely?
Our conclusion is that both the wiffleball and the cusp recycle are working at a reasonable level.
[/quote]

... there we go again, concluding with tautologies. insert '... that we suppose exist ... '. daemons, top to bottom.
POPS isn't really related, afaict, as WB is a Polywell-specific phenomenon.
i'm not sure i would totally agree with that.

to be sure they are not trying to achieve the same thing in the same way, but i suspect that a) the underlying (Maxwellian) mechanisms ' at play', b) amenable diagnostic methods, have much in common.

why else was Rick top man for the job? and why else did he jump at the chance?

(quite possibly lots of reasons, please dont take the question literally).

whatever gives, we've got a lot of catching up to do with the Tokamak guys when it comes to describing whats going on exactly with 'ones plasma'.

MSimon
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Post by MSimon »

See my

viewtopic.php?p=38875#38875

for some thoughts on the matter.
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KitemanSA
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Post by KitemanSA »

rcain wrote:
quoth Rick:
Here’s what we know and what we don’t know:
1. We don’t have the spatial resolution of the density to see if the cusps are quasi-neutral on the WB-7
why not? if its important, surely we aquire some resolution.

seems to me also that much can be determined from even moderate spatial resolution. - Ive seen LIF and Doppler being used in a couple of papers from IEC 2009. (Nice summary of possible techniques - here http://www.answers.com/topic/plasma-diagnostic ).
IIRC, these "quoth"s were pre WB7.1. The whole reason to do 7.1 was to get "better" data. (Ok, maybe only a big part of the reason :wink: ).

One can either believe they got good enough data to support going on to WB8, or that WB8 is a "Recovery Act" boon-doggle, or maybe a bit of both!

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