Pros and Cons of Fusion Power Generation

[M. Simon]

IIRC it was Bussard who said that a polywell device such as WB6 is more akin to a vacuum tube than a Tokamak, so would WB6 be a diode? Thats what I infered from the intro in Chaffee's book. WB6 is a Vacume tube diode. ..?

Due to the electron beams in some ways it is like a beam power tube. Well formation is a beam power tube type phenomenon - a virtual suppressor grid. . The magnetic field makes it kind of like a magnetron diode. Add in grids on your electron guns an you really have a very strange tube.

Electron dominance is the key. Just as it is in most types of vacuum tubes.

 

[RogerFox]

Due to the electron beams in some ways it is like a beam power tube. Well formation is a beam power tube type phenomenon - a virtual suppressor grid. . The magnetic field makes it kind of like a magnetron diode. Add in grids on your electron guns an you really have a very strange tube.

Electron dominance is the key. Just as it is in most types of vacuum tubes.

Then why do so many get hung up by talking the language of Tokamaks?
Rhetorical, I know, sorry.

 

[M. Simon]

Then why do so many get hung up by talking the language of Tokamaks?
Rhetorical, I know, sorry.

Obsolete technology. People haven't studied it for decades. I haven't thought about it much for 20 years or so myself. Now I know more than I ever did.

 

[TallDave]

Hopefully this will help shed some light

This might elucidate a bit.

http://www.sciencemag.org/cgi/content/full/281/5375/307a

http://www.sciencemag.org/cgi/content/full/281/5375/307a" . Rostoker had the last word, which doesn't, of course, mean he was right.

Rostoker's argument seems to hinge on this (click link for equations, haven't been able to paste them):

Carlson employs a classical generic formula for the power density required to overcome the friction between proton and boron beams. This formula is inadequate for the Colliding Beam Fusion Reactor. The magnetic field is important, and it is distinguished by its absence in this formula. The complete formula can be derived by taking the appropriate moment of the Vlasov/Fokker-Planck equation.

Is there an error in his reasoning here?

mheslep, I believe this is what you referred to in #30.

They've just been given $40M to try to make a demo machine that will shock and amaze the world. Not sure what their timeline is, but based on what I remember reading, if we don't hear from them within a couple years then things probably aren't working out. Anyone have a better guesstimate?

 

[M. Simon]

Rostoker says: We have previously considered long, thin cylindrical shell models because they simplify many calculations.

Which says that their reactor model may be based on ease of calculation vs optimum design.

Rostoker says that his machine will require 3.6 Mev of power into get 8.68 Mev (per reaction) of power out at 580 Kev in the center of mass frame.

For Dr. Bussard's machine under similar conditions the drive energy is 1.2 Mev.

 

[RogerFox]

if we don't hear from them within a couple years then things probably aren't working out. Anyone have a better guesstimate?

Tri Alpha is not building a large device at first? Right? I mean they got 5 mill up front, right... so they are not talking about a ITER sized cathedral.

Yeah 2, 3 years tops. I'll bet Tri Alphs gets "Q" @ .65 or under for a buck, anyone else ?

 

[TallDave]

My recollection is that they are first building a smaller device, which is supposed be a good enough neutron source that it can be used for nuclear waste disposal.

Tri Alpha is not building a large device at first? Right? I mean they got 5 mill up front, right... so they are not talking about a ITER sized cathedral.

Yeah 2, 3 years tops. I'll bet Tri Alphs gets "Q" @ .65 or under for a buck, anyone else ?

 

[mheslep]

Carlson employs a classical generic formula for the power density required to overcome the friction between proton and boron beams. This formula is inadequate for the Colliding Beam Fusion Reactor. The magnetic field is important, and it is distinguished by its absence in this formula. The complete formula can be derived by taking the appropriate moment of the Vlasov/Fokker-Planck equation.

Is there an error in his reasoning here?

mheslep, I believe this is what you referred to in #30.

Yes I think when he says with respect to thermalization "the magnetic field is important" he must be wrong, it is not important as I showed inhttps://www.physicsforums.com/showpost.php?p=1370035&postcount=52"

 

[TallDave]

Yes I think when he says with respect thermalization "the magnetic field is important" he must be wrong, it is not important as I showed inhttps://www.physicsforums.com/showpost.php?p=1370035&postcount=52"

Hmm, yes. I was hoping there was a specific flaw in Rostoker's derivation someone could point to. If the magnetic field can't reduce the entropy, it seems to me there ought to be some flaw we could point to in how they introduced it when they took the moment of the Vlasov/Fokker-Planck equation.

Obviously one of the two arguments must be using an inapplicable equation for the thermalization effects in an IEC device of the type described by Rostoker -- and similarly for Bussard's Polywell, to which Rider's thesis should apply as well (I asked Bussard if they might be publishing a detailed paper anytime soon, and he said probably not before the end of the year). It's hard to find much reference that would support either interpretation, but if it were easy we wouldn't be discussing it. Maybe we'll just have to wait and see if either IEC design actually works as the inventors claim.

I give them a 1 in 3 chance of being correct, and only that high because Bussard claims to have those n-counts and seems fairly credible (i.e. unlikely to have fabricated or misinterpreted them).

 

[mheslep]

This might elucidate a bit.

http://www.sciencemag.org/cgi/content/full/281/5375/307a

http://www.sciencemag.org/cgi/content/full/281/5375/307a" .

Well it was between Rostoker and Nevins/Carlson. Nevins w/ LLNL and Carlson at Max Planck. Rider is only cited. Nevins authored the "Can IEC work beyond..." paper in '95 so its to be expected he would publicly reply to the Rostoker-Monkhorst paper in Science 3 years later that basically ignored his well crafted objections to mono-energetic plasmas.

 

[TallDave]

Well it was between Rostoker and Nevins/Carlson. Nevins w/ LLNL and Carlson at Max Planck. Rider is only cited. Nevins authored the "Can IEC work beyond..." paper in '95 so its to be expected he would publicly reply to the Rostoker-Monkhorst paper in Science 3 years later that basically ignored his well crafted objections to mono-energetic plasmas.

Yes, silly of me. I get so used to seeing Rider's name in these discussions, I forgot it was Nevins who made the argument.

 

[TallDave]

Funded by CA?

If this article is accurate, we'll get to find out for sure who's right.

http://www.nextenergynews.com/news1/nextnews7.24b.html

 

[mheslep]

No 'Ca spokesman said', no sources at all, zip. I call BS.

 

[TallDave]

No 'Ca spokesman said', no sources at all, zip. I call BS.

Well, of course there are no sources. It's a leak, not a press release.

It might well be BS, or more likely, have some kernel of truth but not be entirely accurate (e.g., there is discussion of funding Polywell, but no decision yet).

Or it could be a total fabrication, for reasons unknown. Time will tell.

 

[sanman]

I don't know if this has been posted here yet, but here is an interesting approach called the Periodically Oscillating Plasma Sphere:

http://www.lanl.gov/p/rh_pp_park.shtml

So basically it's inertial electrostatic confinement, but in the form of oscillating spheres akin to the sonofusion idea, only using electrostatics instead of sound.

http://fusor.net/board/download_thread.php?site=fusor&bn=fusor_theory&thread=1184299189

 

[RogerFox]

If this article is accurate, we'll get to find out for sure who's right.

http://www.nextenergynews.com/news1/nextnews7.24b.html

false alarm.

 

[sanman]

Does Dr Bussard's IEC fusion device have any reasonable chance of working? (ie. providing net energy output)

What about that POPS thing? I read something that said space charge neutralization in an oscillating plasma puts limits on the amount of compression of the plasma, whereas a steady state plasma has no such limits. So does that mean the POPS idea is a dead end?

 

[TallDave]

false alarm.

We don't know for sure yet.

 

[sanman]

Does Dr Bussard's IEC fusion device have any reasonable chance of working? (ie. providing net energy output)

What about that POPS thing? I read something that said space charge neutralization in an oscillating plasma puts limits on the amount of compression of the plasma, whereas a steady state plasma has no such limits. So does that mean the POPS idea is a dead end?

http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PHPAEN000014000004042701000001&idtype=cvips&gifs=yes

A major issue for electron injected inertial electrostatic confinement (IEC) devices is space charge neutralization. A new formalism is developed that will allow this neutralization to occur for both oscillating and steady-state IEC plasmas. Results indicate that there are limits on the amount of compression that can be achieved by oscillating plasmas while simultaneously maintaining space charge neutralization and parabolic background potential. For steady-state plasmas, there are no such limits and space charge neutralization can be achieved even when the plasma becomes quasineutral.

To me, that sounds like POPS can't be made to work. It's nice that steady state plasmas have no charge neutralization problems, but they're not trying to achieve compression.

 

[sanman]

http://www.ofes.fusion.doe.gov/more_html/2007BPM/BPM2007-Master-Wurden-final.pdf

Look at page 40 on that PDF

 

[mheslep]

So basically it's inertial electrostatic confinement, but in the form of oscillating spheres akin to the sonofusion idea, only using electrostatics instead of sound.

Yes its IEC but no it has nothing in common, even in concept, w/ sonofusion.

 

[mheslep]

To me, that sounds like POPS can't be made to work.

No it means just what it says, there are limits to spherical approach as crafted.. Details in the paper, c.f., cylindrical approaches.

 

[sanman]

mhslep, are you saying that cylindrical might produce better results (ie. less constraint on achievable compression) than spherical?

What would that be called -- POPC?

They don't mention how much difficulty is posed by the constraint on space charge neutralization vs compression factor.

I wish someone could publish a "best neutron count achieved" or a "best energy input/output ratio" or whatever.

Because otherwise it's hard to get a sense of how serious an obstacle the space charge neutralization vs compression ratio problem is.

 

[mheslep]

mheslep, are you saying that cylindrical might produce better results (ie. less constraint on achievable compression) than spherical?

The paper makes clear that the difficulty in using electrons to neutralize the space charge in a spherical device is a geometrical one (angular momentum, etc). That particular issue would likely vanish w/ a cylindrical device as one would simply inject electrons along the central axis. The cylindrical design of course introduces other problems.

 

[Morbius]

The paper makes clear that the difficulty in using electrons to neutralize the space charge in a spherical device is a geometrical one (angular momentum, etc). That particular issue would likely vanish w/ a cylindrical device as one would simply inject electrons along the central axis. The cylindrical design of course introduces other problems.

mheslep,

Yes - cylindrical fusion devices have been studied back in the '70s; which
ultimately culminated with the contruction of MFTF - Mirror Fusion Test Facility.

MFTF was a big cylindrical fusion device; the ends of which were sealed by
huge "yin-yang" magnets.

http://en.wikipedia.org/wiki/MFTF

The following shows a picture of one of the HUGE "yin-yang" magnets:

http://www.llnl.gov/pao/WYOP/Fusion_Energy.html

As the caption states, those magnets were the largest superconducting
system ever built. To get an idea of the size of the "yin-yang" magnets;
the red "sled" that moved the magnets rolled on big logs visible underneath
the sled.

Dr. Gregory Greenman
Physicist

 

[sanman]

What if your electron dispersion for POPS could be maintained as some kind of traveling wave that moved only as the plasma moved? Couldn't that charge dispersion then be considered as static/standing-wave in relation to the plasma, thereby affording the steady-state plasma interpretation that was mentioned as not having any compression limits?

Consider it analogous to electronic valve timing, or the new variable compression ratio technology for car engines.

 

[mheslep]

mheslep,

Yes - cylindrical fusion devices have been studied back in the '70s; which
ultimately culminated with the construction of MFTF - Mirror Fusion Test Facility.

MFTF was a big cylindrical fusion device; the ends of which were sealed by
huge "yin-yang" magnets.

Thanks for the links. Yes I'm familiar and aware that the mirrors were in the end not satisfactory for sealing the cylinder, thus further advancing the torus. However, this is ~unrelated to my post above which discusses inertial electrostatic confinement, not magnetic confinement. Different physics, no thermal ignition with IEC.

 

[mheslep]

What if ...

Electronic valve timing? Read up a little here and let me know if you think its analogous.
http://www.pma.caltech.edu/Courses/ph136/yr2004/0420.1.K.pdf
http://www.pma.caltech.edu/Courses/ph136/yr2004/0421.1.K.pdf

 

[sanman]

Electronic valve timing? Read up a little here and let me know if you think its analogous.
http://www.pma.caltech.edu/Courses/ph136/yr2004/0420.1.K.pdf
http://www.pma.caltech.edu/Courses/ph136/yr2004/0421.1.K.pdf

That talks about waves of the plasma.
I'm talking about having the injected electron charge dispersion move/change/rearrange as the plasma moves. The point was previously made that space charge neutralization by electron injection has limited effectiveness on an oscillating plasma as compared to a steady state plasma. So I'm saying that motion -- even oscillating motion -- is relative. Therefore electron injection could be dynamically modified while the plasma is moving/oscillating so that the electronic charge dispersion and the plasma seem static / steady-state relative to each other. Perhaps this might then alleviate the constraints on achievable compression ratio.

So my electronic timing analogy isn't so terribly out of place, imho.

 

[TallDave]

Bussard's Polywell fusion project was funded btw

Bussard passed away shortly after signing the Navy contract, and Nebel of the POPS paper has picked it up. They have the machine mostly built and are testing components. Nebel says they may have some results by May.

I was going to post links, but it won't let me. You can find the MSNBC mention of the project by Googling Nebel MSNBC.

There is still a lot of debate about whether bremsstrahlung losses will exceed fusion power, which can probably only be resolved by experiment. Nebel believes the ion upscattering is not a problem (see the Chacon reference in the Polywell wikipedia page).

 

[mheslep]

Bussard passed away shortly after signing the Navy contract, and Nebel of the POPS paper has picked it up. They have the machine mostly built and are testing components. Nebel says they may have some results by May.

I was going to post links, but it won't let me. You can find the MSNBC mention of the project by Googling Nebel MSNBC.

There is still a lot of debate about whether bremsstrahlung losses will exceed fusion power, which can probably only be resolved by experiment. Nebel believes the ion upscattering is not a problem (see the Chacon reference in the Polywell wikipedia page).

Yes there's a picture of the latest device up on the EMC2 website w/ some joker locked inside it.
I have the Chacon paper:
Energy gain calculations in Penning fusion systems
using a bounce-averaged Fokker–Planck model

of which Nebel is not an author. Do have information or cite indicating Nebel supports the views in the Miley/Chacon paper?

 

[TallDave]

Do have information or cite indicating Nebel supports the views in the Miley/Chacon paper?

Yes, Nebel has called the paper "the most complete treatise on" the issue (this is in the comments to the MSBNC blog entry mentioned above). He (Nebel) also mentioned at the TalkPolywell site that he discussed the matter with Chacon a couple weeks ago, and they consider the upscatter issue a "red herring" for Polywell.

His full comment, which you can find in the Theory Section of TalkPolywell under topic "worst case scattering and deeper wells":

I had a long talk with Luis Chacon about the ion scattering a few weeks back. We concluded that for the Polywell, these issues were a red herring. The reason is that the densities are so high in the Polywell that you really don't need the ion focussing to be all that good. If you are running a gridded system where particles are lost every 20 passes or so, then it is an issue. For the Polywell, the electron recirculation fraction appears to be ~ 1e5 so the effective energy loss from the electrons is small. Consequently, you don't need huge focussing to get the density high.

 

[mheslep]

I see Chacon's paper cited a couple times; Chacon and Nebel are authors on all of them except the first, a 'how we computed it' paper partly on Chacon's work, and Knoll is also LLNL. I was hoping to see some independent comment.

Jacobian-free Newton–Krylov methods: a survey of approaches and applications - all 8 versions »
DA Knoll, DE Keyes - Journal of Computational Physics, 2004 - Elsevier
Jacobian-free Newton–Krylov (JFNK) methods are synergistic combinations of
Newton-type methods for superlinearly convergent solution of nonlinear equations
and Krylov subspace methods for solving the Newton correction equations. ...
Cited by 159 - Related Articles - Web Search

Experimental studies of electrostatic confinement on the intense neutron source-electron device - all 3 versions »
J Park, RA Nebel, WG Rellergert, MD Sekora - Physics of Plasmas, 2003 - link.aip.org
Theoretical works by Barnes and Nebel [RA Nebel and DC Barnes, Fusion Technol.
[bold 38], 28 (1998); DC Barnes and RA Nebel, Phys. Plasmas [bold 5], 2498
(1998)] have suggested that a tiny oscillating ion cloud may undergo a self- ...
Cited by 5 - Related Articles - Web Search - BL Direct

Periodically oscillating plasma sphere - all 4 versions »
J Park, RA Nebel, S Stange, SK Murali - Physics of Plasmas, 2005 - link.aip.org
The periodically oscillating plasma sphere, or POPS, is a novel fusion concept
first proposed by DC Barnes and RA Nebel [Fusion Technol. [bold 38], 28 (1998)].
POPS utilizes the self-similar collapse of an oscillating ion cloud in a ...
Cited by 3 - Related Articles - Web Search

Stability of thermal ions confined by rigid-rotor electron clouds in Penning fusion systems - all 2 versions »
L Chacón, DC Barnes - Physics of Plasmas, 2000 - link.aip.org
In the Penning fusion device, a spherical cloud of electrons, confined in a
Penning-type trap, creates the ion-confining electrostatic well. Calculations
performed with a bounce-averaged Fokker–Planck model have suggested that ...
Cited by 1 - Related Articles - Web Search - BL Direct

Two-dimensional electron-electron two-stream instability of an inertial electrostatic confinement … - all 5 versions »
A Marocchino, G Lapenta, EG Evstatiev, RA Nebel, J … - Physics of Plasmas, 2006 - link.aip.org
Theoretical works by Barnes and Nebel [DC Barnes and RA Nebel, Phys. Plasmas
[bold 5], 2498 (1998); RA Nebel and DC Barnes, Fusion Technol. [bold 38], 28
(1998)] have suggested that a tiny oscillating ion cloud (referred to as ...
Cited by 1 - Related Articles - Web Search - BL Direct

Equilibrium and low-frequency stability of a uniform density, collisionless, spherical Vlasov system - all 3 versions »
DC Barnes, L Chacón, JM Finn - Physics of Plasmas, 2002 - link.aip.org
Equilibrium and stability of a collisionless, spherical Vlasov system with
uniform density are considered. Such an electron system is useful for the
Periodically Oscillating Plasma Sphere (POPS) fusion system. In POPS the ...
Cited by 1 - Related Articles - Web Search - BL Direct

Space charge neutralization in inertial electrostatic confinement plasmas - all 4 versions »
EG Evstatiev, RA Nebel, L Chacón, J Park, G … - Physics of Plasmas, 2007 - link.aip.org
Inertial electrostatic confinement (IEC) schemes for fusion devices have been
studied both experimentally and theoretically for some 40 years. Purely
electrostatic systems and combinations of magnetic and electrostatic ..

 

[TallDave]

The above-mentioned Park is also on the WB-7 team, btw.

I haven't seen much independent comment either. Might be more after WB-7 results are published, esp. if the larger 100MW demo reactor project gets picked up.

FWIW, Zubrin's "Energy Victory" has a chart showing a strong correlation between oil prices and fusion research funding, so that can't hurt the chances of a Polywell grant.

 

[TallDave]

Sorry to bump again, but people might find this comment from Nebel interesting:

...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 www iter org/a/index_nav_4.htm Tell me what you get.

...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. Even if Rider and Nevins were correct (which Chacon has pretty clearly shown they aren’t) this isn’t a show stopper. It has a lot more significance for Hirsch/Farnsworth machines that have low average densities than it does for the Polywell.

He says 62500, but I assume the 6 is a typo and he meant 2500.