Has Wiffleball Been Created Ever?

[93143]

And on stright question of this thread: "Has Wiffleball Been Created Ever?" nobode could give the simple and clear answer: "Yes" or "No".

That's because we don't have the data. However, from Dr. Nebel's comment here:

viewtopic.php?p=18445#18445

we can infer that they at least tried with WB-7, and considering that WB-8 is now running I suspect they succeeded.

And "cheap" WB-6 we should copare with not costly T-1 TOKAMAK. And not with ITER.

ITER doesn't really have an analogue in the current Polywell roadmap, as far as we know. DEMO does - WB-D. And WB-D should be a couple hundred million.

Of course, we haven't gotten there yet...

As klystrons or any other vacuum tubes run at larger Debye length.

The Langmuir onion concept arose from my realization that the Debye length being much smaller than the machine size made the conventional double-well depiction physically inconsistent. It seems to me that the assumptions underlying Debye shielding are invalid in a Polywell, and that the result would be a pattern of standing Langmuir waves instead. This is 1D and probably overly simplistic, but certain experiments and conceptual descriptions have increased my confidence in the idea somewhat...

...

Quit trying to lead me on a wild goose chase. Polywell power plants are supposed to be ~10 T, not 2 T. End of story. Viability of the concept is a (very large) separate question.

...

P.S. I edited the post with the links (two up) while you were replying. You should probably read the latest version.

[Joseph Chikva]

And on stright question of this thread: "Has Wiffleball Been Created Ever?" nobode could give the simple and clear answer: "Yes" or "No".

That's because we don't have the data. However, from Dr. Nebel's comment here:

viewtopic.php?p=18445#18445

we can infer that they at least tried with WB-7, and considering that WB-8 is now running I suspect they succeeded.

And "cheap" WB-6 we should copare with not costly T-1 TOKAMAK. And not with ITER.

ITER doesn't really have an analogue in the current Polywell roadmap, as far as we know. DEMO does - WB-D. And WB-D should be a couple hundred million.

Of course, we haven't gotten there yet...

As klystrons or any other vacuum tubes run at larger Debye length.

The Langmuir onion concept arose from my realization that the Debye length being much smaller than the machine size made the conventional double-well depiction physically inconsistent. It seems to me that the assumptions underlying Debye shielding are invalid in a Polywell, and that the result would be a pattern of standing Langmuir waves instead. This is 1D and probably overly simplistic, but certain experiments and conceptual descriptions have increased my confidence in the idea somewhat...

...

Quit trying to lead me on a wild goose chase. Polywell power plants are supposed to be ~10 T, not 2 T. End of story. Viability of the concept is a (very large) separate question.

...

P.S. I edited the post with the links (two up) while you were replying. You should probably read the latest version.

I've read his comments: "I’ll leave that as an “exercise to the reader”. For which reader? For reader who argues Polywell is a beam machine or is not a beam machine?
At least, you can't disprove the fact that the wiffleball effect's existence is questionable yet. Will Polywell work without wiffleball? I would answer that yes, but as conventional thermal magnetic trap. Such as: Ioffe trap, In-Ian trap, etc. So, how legit is expectation of WB-D and its comparing with DEMO - even more mature experiment than ITER?

Not Debye shielding but that is only plasma definition: plasma is set of particles whose Debye length lower than geometric dimensions. In such a systems some collective effects are observed. So, stabilization of plasma is much complex than in vacuum tubes. Nevertheless 2-stream instability first was discovered as I know by John Pierce - inventor of traveling wave tube.

You are comparing DEMO with WB-D stating that it will cost several hundred millions. From what is this calculation? Length of superconducting conductors?
Man-hours are needed for development? Components will be purchased from China/India or from USA/Europe?
Dr. Nebel said that scaling was not observed in Polywell yet. Nevertheless he talks about scalling law B**4 R**3. Whether this scaling law is universal for any other concepts? Yes, in case of constant beta. But was constant beta observed in any other devices? No. What evidence that beta is constant =1? Nebel says: “Densities for devices prior to the WB-7 were surmised by measuring the total light output with a PMT and assuming that the maximum occurred when beta= 1. We’re not convinced that this is reliable.” I would say more: condition “beta=1” is impossible for any magnetic confinement concepts. All the more we are talking on desired goal – to achieve 100^4 = 10^8 more power density.

“For first approximation 3 men are enough" - you said. Ok.
But, is that possible or no that your/their estimation of cost will be wrong at more detailed calculation? Are you aware with history of engineering? Is not a very common situation that first approximation of cost is wrong? Does TOKAMAK concept more complex? I think that no. TOKAMAK is based on a very simple idea. And “easy for realization” thought its first developers.

[93143]

Now you're just being contrary. You know as well as I do what the current state of play is, where the estimates come from, etc.

Have you considered the possibility that Polywell really is vastly easier to make work than the tokamak? We obviously don't know yet, but there are reasons to believe that it might be, which is a big reason why it's being researched. The tokamak looked easy back in the day, but with hindsight we can see all the gotchas. Polywell is assessed with the benefit of that experience.

Dr. Nebel has stated (IIRC) that the electron distribution is "isotropic, but not thermal". Given the mass difference and corresponding low energy exchange rate, it seems to me that this pretty much takes care of the electron-ion two-stream instability, depending on how one reads it. (Of course, depending on how one reads it, it sounds like it might be at least partially inconsistent with my Langmuir onion picture...)

I would say more: condition “beta=1” is impossible for any magnetic confinement concepts.

Polywell is inherently magnetohydrodynamically stable. If you push on the field, it gets stronger.

Beta=1, as used by Dr. Bussard, refers to the condition where the diamagnetic plasma squeezes the cusps almost shut. The plasma is supposed to be essentially fully diamagnetic at this point, but I am not sure that it is not fully diamagnetic prior to this point. Past this point, the cusps start to open up again, increasing the loss rate.

This suggests that beta=1 can be considered a controllable set point, rather than an unapproachable asymptote.

[ladajo]

Joseph Chikva wrote:

And on stright question of this thread: "Has Wiffleball Been Created Ever?" nobode could give the simple and clear answer: "Yes" or "No".

Joseph. Why do you not understand that those who know the definitive answer to that question can not answer it in public.

Why do you not concede that there is VERY strong evidence and implications from statements and activities by those who do really know that the answer is "Yes".

I admire your persistence. But at some point you have to accept that others know more than you.

94123 wrote:

This suggests that beta=1 can be considered a controllable set point, rather than an unapproachable asymptote.

I would say it is beyond a suggestion, and an integral part of the Theory Construct. When Beta exceeds 1, the plasma has a blow out. The interesting consideration, is whether or not the machine can be constructed in a manner for steady state ops, that the "blow out" is a self regulation feature, and not an "E-Stop".

As far as the required T for production machines, that remains to be seen. However, I do not think to date anything has suggested that 10T is required.
Josephs point about ion confinement at higher T levels is certainly a fair consideration. With silly T comes more impact to ions. But the T levels envisioned to date do not speak to those issues as a major concern.

[KitemanSA]

I would say more: condition “beta=1” is impossible for any magnetic confinement concepts.

Polywell is inherently magnetohydrodynamically stable. If you push on the field, it gets stronger.

Do't bother arguing beta with Joe, he is stuck on the fact that because of minor perturbations, beta can't be identical to infinite zeros to 1.000... The rest of us use beta=1 to be equivalent to "as hard as you can push without blowing thru", which may only be beta = .998, but that doesn't seem to click in his mind. He just wants to be "right" that beta cannot be "1".

Indeed, beta can be infinite if you understand Dr. B.'s usage.

[KitemanSA]

Dr. Nebel said that scaling was not observed in Polywell yet. Nevertheless he talks about scalling law B**4 R**3. Whether this scaling law is universal for any other concepts? Yes, in case of constant beta. But was constant beta observed in any other devices? No. What evidence that beta is constant =1? Nebel says: “Densities for devices prior to the WB-7 were surmised by measuring the total light output with a PMT and assuming that the maximum occurred when beta= 1. We’re not convinced that this is reliable.” I would say more: condition “beta=1” is impossible for any magnetic confinement concepts. All the more we are talking on desired goal – to achieve 100^4 = 10^8 more power density.

Jeez, yet again Joe reads a simple statement and comes to the wrong conclusion. What a surprise!

[Joseph Chikva]

Dr. Nebel has stated (IIRC) that the electron distribution is "isotropic, but not thermal". Given the mass difference and corresponding low energy exchange rate, it seems to me that this pretty much takes care of the electron-ion two-stream instability, depending on how one reads it. (Of course, depending on how one reads it, it sounds like it might be at least partially inconsistent with my Langmuir onion picture...)

Not background electrons but electron beam + background ions are issue for electron-ion 2-stream. You are going to increase B field 100 times, thus you hope to increase ions number density 10000 times (impossible but let’s admit). Not issue required for investigation? Or such dramatic change will not change plasma properties?

Polywell is inherently magnetohydrodynamically stable. If you push on the field, it gets stronger.

Minimum B principle? Does not work. Recall that for toroidal confinement concepts namely Stellarators provide similar principle. Nevertheless Tokamaks provide better confinement (more stable). The second example are all recently developed and forgotten today magnetic traps (mirror machines).

Beta=1, as used by Dr. Bussard, refers to the condition where the diamagnetic plasma squeezes the cusps almost shut. The plasma is supposed to be essentially fully diamagnetic at this point, but I am not sure that it is not fully diamagnetic prior to this point. Past this point, the cusps start to open up again, increasing the loss rate.

Are you sure that plasma in Polywell is diamagnetic if particles there do not move at closed curve?

[Joseph Chikva]

Joseph. Why do you not understand that those who know the definitive answer to that question can not answer it in public.

At least they made public (only at this board tens thousands people are registered) the main sense of concept.
I think that wiffleball and POPS are only nicknames of nonexisting things thought up only for marketing purposes for getting additional financing.
Very likely that the biggest Polywell's secret is in that it does not work.

Concerning particle losses at beta=1: MSimon qouted link of alfven waves in TOKAMAK responsible for particles losses. Recall that beta in TOKAMAKs has 0.1 order.
Do you not see similarity?

[Robthebob]

Low-energy alphas can be excited artificially (my memory is vague on exactly how), so that they don't stick around and cause problems.

Ion cyclotron heating, I think Dr. Nebel talked about this?

[kcdodd]

I have a hunch that the magnetic field curvature has far more to do with tokamak problems then many proponents would like to admit. As an example, if the direction of plasma pressure gradient is in the same direction as the field curvature, ballooning modes become unstable, one cause for elms. Of course the curvature points outward for polywell field, which makes ballooning mode stable. I don't see an analog between tokamak stability and polywell stability. I think if there is some instability it will be because of different reasons then the tokamak reasons. In a similar vane as the problems with pure ICF and laser instabilities.

[hanelyp]

The Polywell has cusps. Even in wiffleball mode, the cusps appear fairly large to something with the energy of a fusion alpha. They rattle around for ~1e3 passes and then leave. The number density never gets very high.

Not just energy, but also mass/charge ratio. The cusp profile for fusion products would be HUGE compared to what electrons see, dimensions proportional to cyclotron radius. Add in recirculation and electron confinement gets to around (back of envelope) 1e6 times better than fusion product confinement. If annealing works as well as hoped, fuel ion confinement will be better than electron confinement.

Compare to a properly functioning tokomak where all charged particles are confined about equally, and plasma has to be drained off the edges to dispose of fusion products.

[Joseph Chikva]

As an example, if the direction of plasma pressure gradient is in the same direction as the field curvature, ballooning modes become unstable, one cause for elms.

Please do not mix all in one salad. Balloning mode are observed in ant toroidal devices, while elm instability is a feature only H-mode. "H-mode" stands for "high confinement mode". Often TOKAMAK people say "elmy H-mode".
Despite to instabilities lifetime of plasma in TOKAMAKs reaches minutes. Please note me the lifetime of olasma in "more stable" Polywell.

Actually plasma in TOKAMAK is more stable despite to all your or any others arguments.

[kcdodd]

As an example, if the direction of plasma pressure gradient is in the same direction as the field curvature, ballooning modes become unstable, one cause for elms.

Please do not mix all in one salad. Balloning mode are observed in ant toroidal devices, while elm instability is a feature only H-mode. "H-mode" stands for "high confinement mode". Often TOKAMAK people say "elmy H-mode".
Despite to instabilities lifetime of plasma in TOKAMAKs reaches minutes. Please note me the lifetime of olasma in "more stable" Polywell.

Actually plasma in TOKAMAK is more stable despite to all your or any others arguments.

Are you saying ballooning mode isn't a cause of elms? Otherwise I don't know how I could be clearer.

And again, you are confusing the difference between plasma lifetime and confinement time. I have flourescent bulbs here in my garage that have been going for a few hours now. And I am sure there are some neon signs that have been on for years at a time. All plasma discharges with really crappy confinement times. So unless you are saying we might be able to use tokamaks as a good new light-source it really makes no difference how long they can run them. That's merely a practical concern. What matters for fusion break-even is the energy confinement time. Which is right now, at the best of my knowledge, something like 1 second. Also important is the reaction rate, which is why ICF can get away with such crappy confinement times. Incidentally, they also have much shorter plasma lifetimes then all other schemes. Again, that is really kind of irrelevant to the break-even aspect.

[Joseph Chikva]

Are you saying ballooning mode isn't a cause of elms? Otherwise I don't know how I could be clearer.

List of lasma instabilities types:
http://webcache.googleusercontent.com/s ... clnk&gl=ge

Bennett pinch instability (also called the z-pinch instability )
Beam acoustic instability
Bump-in-tail instability
Buneman instability,[2]
Cherenkov instability,[3]
Chute instability
Coalescence instability,[4]
Collapse instability
Counter-streaming instability
Cyclotron instabilities, including:
Alfven cyclotron instability
Electron cyclotron instability
Electrostatic ion cyclotron Instability
Ion cyclotron instability
Magnetoacoustic cyclotron instability
Proton cyclotron instability
Nonresonant Beam-Type cyclotron instability
Relativistic ion cyclotron instability
Whistler cyclotron instability
Diocotron instability,[5] (similar to the Kelvin-Helmholtz fluid instability).
Disruptive instability (in tokamaks)
Double emission instability
Drift wave instability
Edge-localized modes [6]
Electrothermal instability
Farley-Buneman instability,[7]
Fan instability
Filamentation instability
Firehose instability (also called Hose instability)
Flute instability
Free electron maser instability
Gyrotron instability
Helical instability (helix instability)
Helical kink instability
Hose instability (also called Firehose instability)
Interchange instability
Ion beam instability
Kink instability
Lower hybrid (drift) instability (in the Critical ionization velocity mechanism)
Magnetic drift instability
Magnetothermal instability (Laser-plasmas) [8]
Modulation instability
Non-Abelian instability (see also Chromo-Weibel instability)
Chromo–Weibel instability
Non-linear coalescence instability
Oscillating two stream instability, see two stream instability
Pair instability
Parker instability (magnetic buoyancy instability)
Peratt instability (stacked toroids)
Pinch instability
Sausage instability
Slow Drift Instability
Tearing mode instability
Two-stream instability
Weak beam instability
Weibel instability
z-pinch instability, also called Bennett pinch instability

Resistive Ballooning Mode , similar to ideal ballooning, but with finite resistivity taken into consideration, provides another example of a resistive instability.

An edge-localized mode ("ELM") is a disruptive instability occurring in the edge region of a tokamak plasma due to the quasi-periodic relaxation of a transport barrier previously formed during an L --> H transition. This phenomenon was first observed in the ASDEX tokamak in 1981

And again, you are confusing the difference between plasma lifetime and confinement time. I have flourescent bulbs here in my garage that have been going for a few hours now. And I am sure there are some neon signs that have been on for years at a time. All plasma discharges with really crappy confinement times. So unless you are saying we might be able to use tokamaks as a good new light-source it really makes no difference how long they can run them. That's merely a practical concern. What matters for fusion break-even is the energy confinement time. Which is right now, at the best of my knowledge, something like 1 second. Also important is the reaction rate, which is why ICF can get away with such crappy confinement times. Incidentally, they also have much shorter plasma lifetimes then all other schemes. Again, that is really kind of irrelevant to the break-even aspect.

I am confusing nothing. But ok, let's say 1 sec confinement time. Do you not agree that is quite long time period for unstable plasma?

[hanelyp]

Plasma confinement time means little without context, such as density.