Polywell In Europe Raising Funds

[chrismb]

Hyperbole and condescension indeed.

I'm glad we've reached agreement, I was sure we would....

[TallDave]

OTOH, we have the benefit of knowing why tokamaks failed

Please, do tell me more! I wasn't aware that it had failed. So, when did this happen?

As best we can tell, tokamaks aren't economically competitive and probably can't be, barring some game-changing breakthrough. Even the most advanced designs on the board today aren't competitive with fission in terms of plant power density. This is after cumulative spending in the hundreds of billions.

The lack of a plausible path to economic power production is failure.

What's sort of funny is that unlike Polywell, there isn't any debate about whether toks have failed. Everyone knows the designs aren't competitive and that fission will last thousands of years. But the massive thing plods ahead on its own inertia, plus the advancement of science and the faint hope someone will figure out some new twist leading to cheap clean plentiful energy. It's good science, good politics, bad economics.

[D Tibbets]

"to JMC:

Since you are worried about Rider, let me suggest the following exercise. Let's assume that a Polywell reactor is in the wiffleball mode, namely that:

n*kBolt*Te = B**2/(2*mu0)

to make it simple, let's use mks units and assume B = 10 Tesla, mu0 =4.0e-7*pi, Te = 1.0e4 eV and kBolt = 1.6022e-19 Joules per eV.

Calculate what n is and compare it to the ITER value at

http://www.iter.org/a/index_nav_4.htm

"

'ang on a minute!? So the claim here is that a wiffleball is a better confinement surface than a tokamak toroid!

hahhhahhahahahhahhahhahhh!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I think that claim is implied from the entire Polywell approach. But, remember, this claim applies to electron magnetic confinement, decoupled from ion magnetic containment. The ion confinement follows from the electrostatic effects of the confined [EDIT- excess] electrons. As far as I know, in a tokamak, there is no decoupling between the ions and electrons in terms of magnetic confinement, ie neutral plasmas with bipolar flows.

Dan Tibbets

[KitemanSA]

'ang on a minute!? So the claim here is that a wiffleball is a better confinement surface than a tokamak toroid!

hahhhahhahahahhahhahhahhh!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Nope, but the hope and speculation is that the wiffleball, backed up by the MaGrid will be.
Perhaps one reason, the Polywell magnets are a bunch closer.
Perhaps another, the basic ion velocities are supposed to be normal to the powerful field, not along it.
We shall see, eventually. Hope it is not just pie in the sky by and by!

[TallDave]

'ang on a minute!? So the claim here is that a wiffleball is a better confinement surface than a tokamak toroid!

As pointed out above, the tokamak toroid has to confine the plasma, the WB only has to confine the electrons. When your ions have to climb out of an electrostatic well, ion pressure is low.

[chrismb]

You all seem to be half-reading what rnebel wrote.

He [appears to have] said "The upshot of this is that the Polywell has a power density that is ~ 62500 times bigger than ITER EVEN IF THERE IS NO ION CONVERGENCE!"

His supposition is therefore quite clearly that the wiffleball mode is the fabled spherical magnetic 'confinement' surface, and is an improvement over toroidal magnetic 'confinement' surfaces.

...What utter Cobblers!!!....

rnebel just doesn't get off that easily. OK, so maybe he's got a project that's now secret [maybemaybe]. And maybe he's not allowed to talk about that project [maybemaybe]. And maybe there's new stuff he can't talke about [maybemaybe].

But there's absolutely no way you're gonna convince me that a full-blooded scientist won't carry on a discussion about something that he's already said and that has already happened and published, if he's so inclined. He's just not inclined to do so. Why?....

There's absolutely nothing a NEW contract can do to stop someone talking about OLD results and OLD theory. Yet, we hear not a twitter....

He doesn't have to talk about anything new, but any contract that demands he can no longer discuss already published material is clearly including unfair contract terms, which therefore don't apply. As I say, if *I* were to find myself under such a contract, I'd do what I damned well please with OLD info and OLD discussions and let my sponsors suck on their toothless gums.

[TallDave]

"The upshot of this is that the Polywell has a power density that is ~ 62500 times bigger than ITER EVEN IF THERE IS NO ION CONVERGENCE!"

Yes, that means with convergence it could actually be even more than 62,500.

His supposition is therefore quite clearly that the wiffleball mode is the fabled spherical magnetic 'confinement' surface, and is an improvement over toroidal magnetic 'confinement' surfaces.

...What utter Cobblers!!!....

Which part of "only electrons" is confusing you? It's not a neutral plasma, there's a well even if there isn't much focus.

He doesn't have to talk about anything new, but any contract that demands he can no longer discuss already published material is clearly including unfair contract terms, which therefore don't apply

What's the point? There's not much to say about pre-WB-7 results that has't been rehashed to death already. Any discussion would quickly lead to WB-7/WB-8 results, because that's what everyone wants to know.

[KitemanSA]

But there's absolutely no way you're gonna convince me that a full-blooded scientist won't carry on a discussion about something that he's already said and that has already happened and published, if he's so inclined. He's just not inclined to do so. Why?....

Ever had a Navy contract? Data, any data, can have it's authorized distribution limited in any way the contract specifies. All the data is undoutedly labeld as "Defense Technical Information" and thus it's export is unlawful, and presentation on the internet is considered "export" under the intent of the law. If he discusses ANY data related to ANY contract he or EMC2 has EVER had that has not previously been approved with a distribution statement A (Public Release) he can be prosecuted. It all depends on the Navy's contract administrator.

There's absolutely nothing a NEW contract can do to stop someone talking about OLD results and OLD theory. Yet, we hear not a twitter....

Not so. See above.

He doesn't have to talk about anything new, but any contract that demands he can no longer discuss already published material is clearly including unfair contract terms, which therefore don't apply.

Ah, but if Dr. B. went overboard and published info that had NOT been released, Dr. N. would STILL be limited by the export control act. Getting Distro A (Public Release) approval is tough these days, even for unclassified information.

As I say, if *I* were to find myself under such a contract, I'd do what I damned well please with OLD info and OLD discussions and let my sponsors suck on their toothless gums.

Those gums conceal some VERY sharp teeth. You would probably say it all the way to prison. The Navy is protective about its data!

[Art Carlson]

Assuming that the power density advantage (~60,000) is anywhere close, ...

Remind me again where this number comes from. I would have said, given the same fuel, and the same magnetic field strength, the power density scales with beta^2. Taking the beta of a tokamak reactor to be 10% (I think it is expected to be higher, but I couldn't find a solid reference right off) and the beta of a polywell reactor to be 100%, that gives polywell a respectable factor of 100 advantage, but not 60,000.

I had to dig, but I finally found the R. Nebel post about the power density that I based my post on.

JMC and MSimon:
Actually, you need to click on “read more” under the design section, then “main parameters” then on the “more” button. What you will find is that the average density of ITER is ~ 1.0e20/m**3. If you use the formula I sent you for the Polywell, you will get a density ~ 2.5e22/m**3. The upshot of this is that the Polywell has a power density that is ~ 62500 times bigger than ITER EVEN IF THERE IS NO ION CONVERGENCE! Thus, a Polywell should far outperform a Tokamak even with a constant density Maxwellian plasma.

...
Since you are worried about Rider, let me suggest the following exercise. Let's assume that a Polywell reactor is in the wiffleball mode, namely that:

n*kBolt*Te = B**2/(2*mu0)

to make it simple, let's use mks units and assume B = 10 Tesla, mu0 =4.0e-7*pi, Te = 1.0e4 eV and kBolt = 1.6022e-19 Joules per eV.

Calculate what n is and compare it to the ITER value at

http://www.iter.org/a/index_nav_4.htm

Thanks for digging this out. I have trouble remembering things that don't make sense to me. In this case it is a bit sloppy to compare a value from the detailed design of a machine intended to actually be built with a back-of-the-envelope estimate. The main problem is probably taking 10 T at the plasma given 12 T (the ITER value) at the coils.

I couldn't find a number for the field that ITER expects at the plasma, but I expect that it is considerably smaller than 12 T and accounts for much of the discrepancy. The question is whether a polywell reactor, if you did a detailed design, would be much better. In a tokamak you lose maybe a factor of 2 from the toroidal geometry. In a polywell, you lose some because the currents in the coils are locally in oppposite directions. That makes it essential to have fat coils and consider the radial build. I suspect that will saddle you with at least a factor of 2.

There are other factors that you would have to look at more closely. In a tokamak there are profile effects, so the average density and temperature are less than the maximum values. Whether there are equivalent features in a polywell I can't say. It does bother me that Nebel used a simple n*T_e, as if there were no ions or they had no pressure.

It could be that a detailed comparison would come down with further advantages for a polywell, but until somebody publishes one, I will stick with "roughly two orders of magnitude" and leave it at that. (N.B. Two orders of magnitude in the power density. None of this calculation has any bearing on the energy balance or the minimum size, if any, at which a reactor could produce net power.)

[TallDave]

http://nstx.pppl.gov/DragNDrop/Five_Yea ... ofiles.pdf

Whether there are equivalent features in a polywell I can't say.

This is one of those things we'd really, really like to know. Hopefully WB-8 will shed some light, but given the history of fusion efforts we probably shouldn't be surprised if new things emerge in WB-9.

It does bother me that Nebel used a simple n*T_e, as if there were no ions or they had no pressure.

It's almost as though he expects some other force to be confining them...

I will stick with "roughly two orders of magnitude" and leave it at that.

As always, interesting arguments, but I'm still leaning towards five (with ion focus). This exercise may be BOE, but Rick and company have been working on detailed reactor designs, so there's probably some fairly sophisticated thinking behind it.

[Betruger]

As I say, if *I* were to find myself under such a contract, I'd do what I damned well please with OLD info and OLD discussions and let my sponsors suck on their toothless gums.

Key word "I".

[D Tibbets]

...
His supposition is therefore quite clearly that the wiffleball mode is the fabled spherical magnetic 'confinement' surface, and is an improvement over toroidal magnetic 'confinement' surfaces.

...What utter Cobblers!!!....

I don't know what the toroidal confinement surface efficiency is, but R. Nebel has mentioned that the Wiffleball containment is ~ 1000 times better than mirror confinement. I assume this accounts for his statement that a fusion alpha will bounce around ~1000 times before escaping through a cusp, versus A. Carlson's comment that he would expect only a few passes before the alpha escaped. This is a representation of the magnetic confinement of ions that are traveling too fast to be contained by the potential well. I am conviently assuming that there is alot of data that supports this in research up to WB6, and then WB7 and 7.1 with perhabs alternate and possibly more percise methods. So, yes ... What utter Faith!!!.
The actual data reveiled by R. Bussard, despite his assertion that he would make the whole system open (probably his final fall back position) is almost nil, except for the possibly least significant data represented by the neutron counts. The articles in the 1990's I have read do not reviel much data, only conculsions and mathmatical discriptions. I remain convinced that the restoration and subsequent new funds by the Navy was motivated, at least in part, by a desire to keep control of this data (old and new).

Dan Tibbets

[D Tibbets]

In reply to Art Carlson's last post, and to expand on what TallDave said.
The assertion that ions contribute little to the pressure on the magnetic field, seems strange. I would think the various charged particals would all be contibuting to the 'pressure'.

I suspect that the reason this doesn't apply (if true) is due to apparently profound effects caused by the ~ 1 ppm excess of electrons maintained in the system. Near quotes like 'the non upscattered fuel ions are kept out of the magnetic domain by the potential well' is representative of not only tremendous effective electrostatic ion containment, but also the nature of the wiffleball formation and maintainance. ie- the ions may contribute to the absence of the magnetic field within the plasma, but the 'pressure' pushing the magnetic field outward is due (mostly?) to the initial surge of electrons, and subsequently maintained due to a seemigly tiny excess of electrons. I'm guessing this can occur due to the tremendous power of coulomb forces of even a small imbalance of charges. I'm also guessing that if there was not this small excess of electrons there would not be a Wiffleball. You might pump in a huge amount of neutral plasma, with the nessisary magnetic strength to contain it, but the confinement would be mirror confinement, not the much more efficient Wiffleball confinement (~1000X).
Perhaps a stupid conclusion (I am good at those ) would be to say that since there is a 1000X improvement in cusp pinching due to the excess electron charge, then the ions contribution to the plasma pressure pushing out the magnetic field (and pinching the cusps) is one thousandth that of the electrons.

Dan Tibbets

[chrismb]

I don't know what the toroidal confinement surface efficiency is

Answer: as good as you can get by a Royal Mile. A toroid is the only closed surface geometry that can do it.

but R. Nebel has mentioned that the Wiffleball containment is ~ 1000 times better than mirror confinement.

Of course he would. He's got his sponsors to convince, and he also pretends he can't answer any questions, due to contract reasons, so he says anything he likes and knows his talk-polywell audience will suck it up. (Hence the term "suckers", I guess.)

{I'm not trying to be offensive, I'm just trying to be 'provocative' enough so that some technical dialogue might result from it. Believing in what one person says just because he says it, without a chance to cross-examine, is how cults and religions start. "Polywell" is cult-like and I'm desparately trying to keep my interest technical rather than having to cast doubt on, or second-guess without any real means to clarify, the words of the dogmatic Guru and his obediants.}

[TallDave]

Ha. If Polywell is a cult, tokamaks are tithing a tenth of your income and stoning Galileo.

I don't know why people who are clearly quite intelligent still don't seem to understand the most basic Polywell concepts like the lack of ion pressure. This isn't exactly Apocrypha or a hidden sacred text only available to the anointed few. I mean, come on: IEC. It's right there in the name.

Of course it's an inferior surface. If it was trying to contain a neutral plasma it would do a terrible job relative to toks. We're not pumping 10MW of electrons into the plasma just for fun.