Aviation Week on the Lockheed Skunkworks CFR

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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RodCarlson
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Re: Aviation Week on the Lockheed Skunkworks CFR

Postby RodCarlson » Fri Nov 07, 2014 1:10 am

On that note of Carnot efficiency conversion it would also be much easier to thermally absorb and insulate the fusor furnace if compact versus several apartment buildings large.

D Tibbets
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Re: Aviation Week on the Lockheed Skunkworks CFR

Postby D Tibbets » Fri Nov 07, 2014 4:53 am

Ivy Matt wrote:I just found this article on the website of the Max Planck Institute for Plasma Physics, linked to from the ITER website:

Are mini fusion power plants possible?

The short answer, according to them, is "no". In addition to specific arguments relating to the Lockheed Martin concept, here is their general argument:

...attaining a positive energy balance, i.e. producing more fusion power than needed for heating the plasma, calls for extremely good thermal insulation of the plasma, viz. about 50 times better than styropor. In a power plant a temperature in the plasma core of 100 to 200 million degrees is needed, while at the walls no more than 1,000 degrees is tolerable. Such large temperature differences in the plasma drive turbulent flows that mix hot and cold regions with one another, i.e. impair the thermally insulating effect of the magnetic field. This has to be compensated with a larger volume.


There are two obvious defects in this reasoning as it applies to polywells. First, speaking of fusion heating of the plasma ignores that this is not relevant in the polywell. Secondly, the turbulance mentioned may apply to edge unstable plasmas, but not in the Polywell as there is no edge instabilities/ eddies. In effect, the edge insulating properties are much better in the Polywell. And, the temperature is not maintained by fusion (not an ignition machine), but by electrostatic forces (may need suppliment with microwaves, etc.). Heat loss may be a problem, but with much less ExB losses, the heat loss to the shell is primarily radiative. That and hot external electrons, which is much less than internal electrons, by a factor of ~1/100,000 multiplied by the injection inefficiency, and this has various possible permutations.

The intensity of heating on exposed surfaces is indeed limiting. M. Simon led discuaaions on the thermal loads walls could be expected to handle without significantly improved materials and cooling capacity. A number of ~ 1-2 MW per square meter is currently reasonable. In even a large tokamak with resultant lower thermal loads per surface square meter, there are areas wher the thermal load may be very dificult to manage. The diverter in the tokamak has been mentioned of having to handle up to 30 MW per square meter.

The Polywell has a first wall that is the magrid. But this is exposed to only a portion of the heat due to magnetic shielding, basically that portion of the losses due to ExB diffusion, and radiative bremsstruhlung exposure, and neutrons (if present). Fusion energy ions are a small concern because they do not undergo many collisions before cusp escape, so there is little fusion ion ExB diffusion. The vacuum vessel walls eventually intercept any energy not absorbed by the magrid, but this may be 2-3 times as wide as the magrid. Also, with direct conversion, perhaps as much as ~70% to 80 % of the KE in the machine is removed without any thermal loading at all.

The thermal loading in other small machines may be more problematic. FRC, especially the scrape off layer, if present may be a problem. The DPF is perhaps the most compact and handing the thermal loads will be a challenge. Keep in mind though that these machines may also lend themselfs to direct conversion.

In short, the criticism is at best, highly flawed.
Dan Tibbets
To error is human... and I'm very human.

D Tibbets
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Re: Aviation Week on the Lockheed Skunkworks CFR

Postby D Tibbets » Fri Nov 07, 2014 5:20 am

RodCarlson, you idea of the alternalting the polarity of adjacen magnets may actually be good. But I don't think you could maintain this alternate polarity in three dimensions. At, least with a truncated cube shape. Perhaps with a higher order polygon?

Note, that when I said there was no magnetic fields in the contained plasma, I used the gross qualifier.On the edge where the electrons are turned back towards the center, it is obviously due to magnetic influence, but the electrons spend the vast majority of their time inside this border region. The ions, at least ideally, never reach the radius of the border where the magnetic fields from the electromagnets are3 compressed to.
Each moving charged particle produces it's own magnetic field, and this effects any other moving charged particles in the system. Like Gauss Law reasoning though, this 'micro' magnetic field influence is countered by all of the other 'micro' B fields from other moving charged particles. The net effect is no net magnetic field effects. This is different in the tokamak as the majority of charged particles have a common vector.

In the Polywell, it is not only that the electromagnetic field is excluded to the Wiffleball border, the plasma itself in not magnatized due to any bulk movement(spin of the plasma), this would change if the plasma was spinning. Some have proposed that this might be beneficial for containment. Maby, but this difference in having a magnetic plasma has to be considered in the reasoning.

Dan Tibbets
To error is human... and I'm very human.

RodCarlson
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Re: Aviation Week on the Lockheed Skunkworks CFR

Postby RodCarlson » Sat Nov 08, 2014 10:11 pm

Hi Dan,

From the Wiki of biconic Cusps I've posted the picture a quote of text below:

Unfortunately for some reason the image isn't showing up inline. So please all go set your browser address to:

http://en.wikipedia.org/wiki/File:Biconic_Cusp.jpg
Image

"The magnetic fields in this system were made by electromagnets placed close together. This was a theoretical construct used to model how to contain plasma. The fields were made by two coils of wire facing one another. These electromagnets had poles which faced one another and in the center was a null point in the magnetic field. This was also termed a zero point field. These devices were explored theoretically by Dr. Harold Grad at NYU's Courant Institute in the late 1950s and early 1960s.[2][3][4] Because the fields were planar symmetric this plasma system was simple to model.
Particle behavior

Simulations of these geometries revealed the existence of three classes of particles.[5] The first class moved back and forth far away from the null point. These particles would be reflected close to the poles of the electromagnets and the plane cusp in the center. This reflection was due to the magnetic mirror effect.[6][7] These are very stable particles, but their motion changes as they radiate energy over time. This radiation loss arose from acceleration or deceleration by the field and can be calculated using the larmor formula.[8] The second particle moved close to the null point in the center. Because particles passed through locations with no magnetic field, their motions could be straight, with an infinite gyroradius. This straight motion caused the particle to make a more erratic path through the fields. The third class of particles was a transition between these types. Biconic cusps were recently revived because of its similar geometry to the Polywell fusion reactor.[9]"



When you talk the polywell ion particles of no spin in the polywell cusps you are talking about the blue particles in the picture above (called erratic), whereas I don't diagree that those erratic particles of no spin would exist, I'm also talking about stable (red) and transition (pink) ion motions as well. You do agree that the stable and pink ion motions exist right? Or are we missing something here?

See the thing to me is that the stable (red) can change to transitionary or erratic. And I think the advantage of looking at the H fields not just at the cusps is that we can take advantage of ions flowing here and even accelerate them using an oscillating magnetic external coil fields to become erratic (blue) instead. Yes spinning particles would create there own issues, but ignoring them is like pretending they won't or don't occur in the polywell. I don't see how that is possible given that cross products and spins are apt to happen to misforunately aligned erratic particles to the field H lines. True that the spinning variety have more losses predicted by Larmor formula, but they are also acceleratable to much the same kind of external magnetic fields. To me I don't think of the Polywell as an ideal erratic ion device, that might have been the goal of how Bussard seen it at the time as the most likely to yield fusion because of the extra losses due to Larmor radiation of the stable and transitory types damping themselves out faster. But that doesn't mean these ions can be ignored or don't exist. Or better yet in an accelerator of changing magnetic field can't be used to generate erratic ones from the their spinning (stable) ones. I keep trying to convince you the model of only erratic type ions in a magnetic cusp is simplfied one (assuming fast damping of other types), you can't have particles that even deviate a slight amount with the external field lines and not expect a magnetic spin to results. Thats as simple as 101 EM of charged particles, but maybe Bussard in his model was able to eliminate them as feasible for lossy reasons.

As far as net magnetic field of plasma being neutral I agree with this statement whole heartedly. I think of that like this. If I had a straight wire flowing with a current upward, and I want to know the H fields I would perform Amperes Law of Integration around that wire. In other word the current/(perimeter of circle =2piR). I then subject this wire to an external magnetic field the wire would experience a force=iLxB. Now I put another wire exactly parallel the first wire and run current in the opposite direction and tape them together so they can't pull away from each other. Amperes Law would sum up the current as being zero between the two wires so there would be a net zero H field and no interaction as a set of wires tied together to external magnetic field H/B. With no net current being they cancel each other there would also be no net Lorentz iLxB force. That however doesn't mean that the ions traveling in each wire do not feel the force of the external magnetic field H. In fact the iLxB of one wire creates a negative force of -iLxB of the second wire and the two forces push the wires against each other and balance as sum zero force externally. Still Hall voltage and iLxB still applies to each of the ions in the individual wires. In the same way you can say plasma moving in both outward and inward direction create a net zero current, but there is still an interaction with the external H fields. This is why the literature I provided above proves EM 101 that these spinning particles exist in the biconic cusps (aka Polwell derivative), they have to exist. True they might not be what Bussard wanted to focus on in creating fusion in his machine (because of losses of radiation and damping out factor), but that doesn't mean we can say they don't exist in the Polywell. Further with a little introspection we might be able to utilize these ion paths to do what I think Lockheed is doing in their deriviative of a Polywell.

Yes the dyamics would change on the Polywell and I'm fine with that if it is justified. I'm trying to justify doing that but I have the chicken and egg paradox first and just going to model it a 3-D Ansoft plasma to see if indeed any acceleration occurs by an oscillating external fields of the Helmholtz. If that doesn't do what I expect there would be no further argument of mine to even worry about erratic versus stable versus transitory ions in a polywell. I'd really just resign without any argument, simply by not caring anyway.

Regards,
Rod

Betruger
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Re: Aviation Week on the Lockheed Skunkworks CFR

Postby Betruger » Sat Nov 08, 2014 11:57 pm

You can mirror or upload pics on the net using imgur.com Uploading there is straight forward. Click here at the top of the imgur homepage:
Image
No sign up or sign in - just select image, upload, grab uploaded image's URL.
You can do anything you want with laws except make Americans obey them. | What I want to do is to look up S. . . . I call him the Schadenfreudean Man.

RodCarlson
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Re: Aviation Week on the Lockheed Skunkworks CFR

Postby RodCarlson » Sun Nov 09, 2014 12:16 am

Actually also if my theory of the oscillating field winding is correct about being a gridless accelerator, I can explain the reason for the third coil as well in the center of the two opposing Helmholtz coils. Its just kind of falls out so I'm getting a bit pumped if only the FEM software can prove an acceleration of ions by oscillating the external Helmholtz coils. I'll save the details until I can verify the accelerator effect just because I choose to not waste anyone's time yet.

Regards,
Rod

bennmann
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Re: Aviation Week on the Lockheed Skunkworks CFR

Postby bennmann » Sun Nov 09, 2014 5:04 am

RodCarlson wrote:Actually also if my theory of the oscillating field winding is correct about being a gridless accelerator, I can explain the reason for the third coil as well in the center of the two opposing Helmholtz coils. Its just kind of falls out so I'm getting a bit pumped if only the FEM software can prove an acceleration of ions by oscillating the external Helmholtz coils. I'll save the details until I can verify the accelerator effect just because I choose to not waste anyone's time yet.

Regards,
Rod


I'd listen to your details :)

D Tibbets
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Re: Aviation Week on the Lockheed Skunkworks CFR

Postby D Tibbets » Sun Nov 09, 2014 6:06 am

RodCarlson, your mirror machine illustration is difficult (for me) to reconcile with the Polywell . There are a percentage of electrons and even ions that are embedded in the electromagnet B field and follow spiraling trajectories as shown. But, most of the ions are in the magnetic free core. I think the labels are misleading in this context. A stable electron (or ion) mirroring back and forth along a B field line is certainly stable in a COLLISIONLESS plasma. The boundary zone may apply to the electrons only (only when they turn around), while the ions , and electrons spend most of the time are in the ' unstable zone' also. What is important here is that the cusp holes are tiny, so the term unstable reflects the confinement time, which is dictated by the likelihood of the particle (the electron) traveling almost parallel down a cusp opening. The so called stable particles are actually far from that because in any plasma of interest for useful fusion production, the density is relatively high, and thus the collisions are so frequent that stable mirroring oscillations are quickly disrupted- thus ExB diffusion , etc . In the 'unstable zone' they fly in lines dictated by Coulomb collisions and by the space charge/ potential well created by the excess electrons. There is no spiraling at all. The electromagnet B field is not only weaker, it is absent. The influence of collisions not only become dominate over the B field, they are absolute (to many orders of magnitude). There is no magnetic influence. The same is true for electrons, except the typical electron flies outward, till it hits the Wiffleball border, there it turns back almost the reverse of it's approach vector. Only while making that ~ 1/2 turn- orbit is it under the influence of the electromagnetic confining field. The rest of its life it acts without magnetic influence(the magnetic influence from the electromagnets may not be absolutely zero, but it is close enough that it can be considered so. Keep in mind that this considers the ideal situation.

The pressure of the plasma does expel the surrounding electromagnet B field- compresses it outward. It is apparently the electron pressure that does this since they are fast on the edge. It is like a gas in a balloon. The impacts keep the balloon inflated while the particles rebound from that surface. There does not have to be a gross global internal magnetic field to do this, it is the kinetic energy of the charged particles with their individual electromagnetic fields that does the pushing. I lack the background to describe it further. Several of the links describe this field free interior with external B field inflation though. The Wikapedia article seems to be more descriptive of the Polywell than what I remember, perhaps it has been updated.


If you can find this reference from Dr Parks paper it is useful. It seems I saw this but all I get now with Google search is a 1958 conference report.

H. Grad, in Proceedings from Conference on Thermonu-
clear Reactions (University of California, Livermore,
1955) p. 115.

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

Wiffle-Ball Confinement
In 1955, Harold Grad theorized that a high-beta plasma pressure combined with a cusped magnetic field would dramatically improve plasma confinement.[18] Following this idea, Bussard repeatedly claimed that at β = 1 the central electron cloud would become diamagnetic and would push the magnetic field lines back, out from the center; almost closing the cusps through which electrons can escape, increasing the number of electrons being trapped inside.

Possibly useful references:
http://arxiv.org/pdf/1406.0133.pdf

http://www.unz.org/Pub/GradHarold-1957

And the preprint paper by Dr Parks:
http://arxiv.org/pdf/1406.0133.pdf
Page 1
Grad and others predicted theoretically that the plasma confinement properties of the cusp configuration would be greatly enhanced if the magnetic field exhibits a sharp boundary separating the field-free high Beta plasmas and the vacuum region with magnetic fields, as shown in Figure 1B.


Dan Tibbets
To error is human... and I'm very human.

hanelyp
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Re: Aviation Week on the Lockheed Skunkworks CFR

Postby hanelyp » Sun Nov 09, 2014 5:29 pm

http://en.wikipedia.org/wiki/File:Biconic_Cusp.jpg, despite the .jpg extension, isn't an image URL. Try http://upload.wikimedia.org/wikipedia/en/7/7d/Biconic_Cusp.jpg, Image

This illustration strikes me as a low beta field configuration. In a high beta situation, aka wiffleball, the plasma crates an enlarged region of negligible magnetic field in the center, where erratic particle paths across this region dominate.
The daylight is uncomfortably bright for eyes so long in the dark.

Betruger
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Re: Aviation Week on the Lockheed Skunkworks CFR

Postby Betruger » Sun Nov 09, 2014 9:14 pm

We're a very low traffic website, but nonetheless wikipedia is a non profit service to the world (basically) and they're far enough from sustainability that they're perpetually asking for donations.

So I reckon it's minimum courtesy to relieve their traffic by mirroring "their" images, rather than inlining.
You can do anything you want with laws except make Americans obey them. | What I want to do is to look up S. . . . I call him the Schadenfreudean Man.

goldfish
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Re: Aviation Week on the Lockheed Skunkworks CFR

Postby goldfish » Mon Nov 10, 2014 6:01 pm

I found this:
http://iopscience.iop.org/0741-3335/55/6/063001/article

Looking at this Russian design from 2012 it seems that Skunkworks' T4 was heavily inspired on this. There is lots of technical data but I am no expert on fusion. It looks promising though.

Anyone out there who is an expert on these matters?

hanelyp
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Re: Aviation Week on the Lockheed Skunkworks CFR

Postby hanelyp » Tue Nov 11, 2014 12:33 am

goldfish wrote:I found this:
http://iopscience.iop.org/0741-3335/55/6/063001/article

Looking at this Russian design from 2012 it seems that Skunkworks' T4 was heavily inspired on this. There is lots of technical data but I am no expert on fusion. It looks promising though.

Anyone out there who is an expert on these matters?

No more than the skunkworks design resembles magnetic mirrors in general, which isn't all that much. The skunkworks design, as I make it out, is characterized by a central magnetic well and axial cusps.
The daylight is uncomfortably bright for eyes so long in the dark.

Solo
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Re: Aviation Week on the Lockheed Skunkworks CFR

Postby Solo » Tue Nov 11, 2014 2:27 am

So word through the grape vine at the recent APS meeting is that this project was about to get shut down by Lockheed-Martin, and the publicity stunt was an effort to secure some extra funding and/or an internal-politics move to keep them from being de-funded. Makes sense now.

crowberry
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Re: Aviation Week on the Lockheed Skunkworks CFR

Postby crowberry » Tue Nov 11, 2014 1:13 pm

Solo wrote:So word through the grape vine at the recent APS meeting is that this project was about to get shut down by Lockheed-Martin, and the publicity stunt was an effort to secure some extra funding and/or an internal-politics move to keep them from being de-funded. Makes sense now.


Can you please elaborate on what you mean by "publicity stunt"? Does it refer to the 2013 Google Solve for X talk by Charles Chae or to the LM press release, Aviation Week articles and corresponding press conference in October this year?

ladajo
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Re: Aviation Week on the Lockheed Skunkworks CFR

Postby ladajo » Tue Nov 11, 2014 2:36 pm

I heard something similar.
The (LM) approach is reportedly not well received by community plasma physicists. I have heard that the concensus is they have a ways to go beyond glossy photos of shiny stuff.
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