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

Post by RodCarlson »

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Betruger
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Re: Aviation Week on the Lockheed Skunkworks CFR

Post by Betruger »

Rod you can edit your posts. The edit button you click to access edit-mode is at bottom right of a post's frame.
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D Tibbets
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Re: Aviation Week on the Lockheed Skunkworks CFR

Post by D Tibbets »

RodCarlson wrote:Another way to see this AC energize Polywell creating recirculating acceleration along its H lines is to imagine that you now have something with an accelerator without grids or screen losses to steel the energy around each pass. So basically we are looking once more at what Farnsworth/Polywell were aiming to do with a gas pedal.

Rod
Well, I suspect I may be left in the dust here, but it sounds like what you are describing is somewhat similar to a cyclotron. Circulating a plasma and accelerating it with variations in the B field and / or electrostatic fields. This might fit the Lockheed illustrations with more than three magnets, not to mention an end magnet outaisde the vacuum vessel. As for heating via compression, if the plasma then expands to original dimensions, I would think the heating would be countered by subsequent expansion cooling during each cycle.But...
The only image of actual plasma looks like opposing magnet arrangement with line cusp and point cusp-this is Polywell like though of a different geometry. It matches plasma pictures I have taken excepy wit permanete magnets. It also matches some magnetic modeling . That they mention high Beta, and, I think, a potential erll well, I don't see much deviation from the Polywell model except for directions of the line cusps with a larger diameter central magnet instead of an assemblage of 4 ring magnets in the Polywell forming the 'central magnet'.

I suspect some AC or pulsation of the magnets may be needed to aid electron injection, or conversely pulsations in electron gun intensity or voltage to push differentially on the cusp regions, thereby effecting deformations in the B fields- sort of like global magnet pulsation, except perhaps more localized.
But as a method of confinement?

Speaking of magnetic pressure required to contain and compress a neutral thermalized plasma, it is indeed great, by my understanding, but to contain and compress a non thermal electron plasma, the pressure can be much less .In the Polywell because the hot electrons are on the outside, while the hot ions are concentrated inside. As pressure is nRT only the electron pressure needs to be addressed. I don't know if this makes any sense.

You should read both the EMC2 patent applications, perhaps several times to appreciate some of the nuances. They should be available on Askmar.com

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

RodCarlson
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Re: Aviation Week on the Lockheed Skunkworks CFR

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D Tibbets
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Re: Aviation Week on the Lockheed Skunkworks CFR

Post by D Tibbets »

This arrangement might be doable with a Polywell arrangement. But, what about a linear arrangement like the the Lockheed design.? In a small machine, if the ions are following these flux lines along with the electrons, ExB diffusion will be a problem. As Bussard quoted, magnetic fields are no d'arn' good for confining ions, but electrons is a different matter, all because of ExB diffusion issues. You can get it to work, but only by growing the size to tokamak proportions. Also, this magnatized plasma may suffer from edge instabilities. And can you push the density to near Beta= 1 conditions with this open circulating design? Finally, can you establish a potential well which confines the ions away from magnetic influences? The loops look fine in two dimensions but what happens when you add the third dimension? I don't know if this might work, but the edge instabilities and ExB diffusion issues certainly doomed the solenoid designs. There has been a single ring magnet design which may essentially have been this (floating dipole?), but it has never gained any traction. George Miley is one who tried a version of this and did get some containment, but not much. He used cathodes on either end to drive electrons towards the ring core and a positive charge on the inside surface of the ring to balance the negative space charge from converging electrons.

Dan Tibbets
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hanelyp
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Re: Aviation Week on the Lockheed Skunkworks CFR

Post by hanelyp »

D Tibbets wrote:... if the ions are following these flux lines along with the electrons ...
Without using an electrostatic well I'm not seeing a way to prevent that.
And can you push the density to near Beta= 1 conditions with this open circulating design?
I'm thinking no. Magnetic field profile in the outside portions of the loop is poor.
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RodCarlson
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Re: Aviation Week on the Lockheed Skunkworks CFR

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RodCarlson
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Re: Aviation Week on the Lockheed Skunkworks CFR

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RodCarlson
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Re: Aviation Week on the Lockheed Skunkworks CFR

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D Tibbets
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Re: Aviation Week on the Lockheed Skunkworks CFR

Post by D Tibbets »

I think there may be some confusion in this thread about the plasma in a Polywell. Hopefully, the confusion is not mine. The Polywell is not a neutral or magnatized plasma. To first order, at least if Wiffleball conditions are obtained, there is very little spiraling of charged particles along field lines inside the machine. Outside the machine is a different story as that reqion is at low Beta. With high Beta- strong plasma preasure pushing against B fields leads to the gradient of the B field increasing as the pressure increases. As described by Bussard and first by whats his name in the 1950s, the border becomes sharp. The gyroradius is essentially larger than the B field gradiant. This means the charged particle only completes a single 1/2 orbit before the long parabolic portion of the orbit carries it well back towards the center or even to distances wider than the machine. The particle acts like it is rebounding from a hard surface and it travels across the machine or its motions become dominated by collisions before it can complete one spiraling highly parabolic orbit. There is no magnetic memory. And, the plasma does not create any net B field itself, because motions in one direction cancels motions in the opposite. There is no dominate direction like in a tokamak so the plasma does not create a gross magnetic field. Another componet of the Polywell is the electrostatic potential well that creates a centrally directed trap for ions. Ideally, the ions do not interact with the magnetic coils at all. This is why you can claim ExB losses for electrons alone. Because of this the energy loss with electron ExB losses are ~ 1/ 60th or less than the losses would be for ions. In the patent application, the ExB losses for the Polywell was anticipated to be ~ 1-10% of cusp losses (I don't know if this was before or after electron recirculation considerations). If the plasma was neutral, without an ion containing potential well, the losses would be dominated by ions through ExB diffusion. This on top of electron cusp losses. Also, the plasma cannot deviate much from neutrality, so the entire energy picture changes. With looping magnatized plasma, presumably neutral, you would have these ion derived ExB losses. Even, worse, you also have macro instabilities/ edge instabilities to add further to the losses.

Again, ExB and edge instabilities outside the core are bad and cannot be avoided. But, what about the electrons escaping and recirculating in a Polywell? Here, I think, the saving grace is that these streams of electrons are at much less density compared to the core density. These losses relative to the core fusion generating ability is thus greatly dilluted. This density differential inside and outside of the machine is essential for this, and this absolutely needs the high Beta (Wiffleball effect) to succeed. This is why Richard Nebel (once the lead scientist at EMC2) stressed that achieving the Wiffleball effect was essential if there was to be any chance for breakeven with a machine of this type. It is not only that high Beta is good for dense power machines, it is essential for operation. This basic requirement was apparently demonstrated by Dr Parks, and why it is so important. That is why I am pessimistic that any cusp design that does not allow for high Beta and electrostatic ion trapping would work. Some of these considerations would seemingly apply to field reversed approaches. I don't know how they are addressing these issues.

Mention of preferred direction of a charged particle on a B field line is certainly reasonable. Electrons will spiral one way and ions in the opposite. In a collisionless plasma and without mirroring this is significant. But, once one or more mirrorings/ bounces occurs (and you need perhaps 100,000 of these per electron for the machine to work), the direction back and forth becomes essentially even. Then there is the sharp edge effect with Wiffleball. Only 1/2 spiral is completed before reentering the collision dominated core. There will be a small deflection from the presumed perfect radial direction. This would defocus electrons and any up scattered ions that reach that high in the machine. This might be considered to rapidly add spin to the electrons at least. But, consider that the B field border/ lines are convex towards the center and there are separate inward bulges for each magnet. This curvature may effect rebound direction more than the small 1/2 spiral displacement. Also, an electron that rebounds at an angle much away from the core will hit the next magnet flux line and after two or more such rebounds, it will achieve a more central vector. This is comparable in using two or more bounces on a pool table to return the ball to its origin. Bussard addressed this in one of his papers- mostly as applied to up scattered ions.

I mention all of this to illustrate the many considerations that come together in the Polywell, and all of which are required in order for this cusp system to work. Granted, if you stick to D-T fusion you are facing considerably less challenges. But, D-T fusion has it's own unique can of worms.

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

RodCarlson
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Re: Aviation Week on the Lockheed Skunkworks CFR

Post by RodCarlson »

You are correct about ExB losses. I did a bit of study and realized how much was lacking on my part. Appreciate your patience all and think I'll return to RF engineering instead of plasma studies. :D. It has been fun and I saved myself a few hours using Ansoft plasma solutions. I'm removing a lot of my comments because I find them a distraction to the polywell theory.

Regards,
Rod

Ivy Matt
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Re: Aviation Week on the Lockheed Skunkworks CFR

Post by Ivy Matt »

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.
Temperature, density, confinement time: pick any two.

RodCarlson
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Re: Aviation Week on the Lockheed Skunkworks CFR

Post by RodCarlson »

Hi Dan,

Well I went to bed last night recognizing the folly of arguing against the loss of ExB and containment of neutral plasma. I also realized that my idea of of charged particle containment was corkscrewy (literally) in explaining the interactions of charged particles to the external magnetic fields of the Polywell configuration.

But then something of a partial redemption came to me in the early hours this morning, unfortunately too late for my editing and removal of my previous comments. I asked myself a simple question, did I somehow draw the H fields wrong for the Polywell configuration of Helmholtz coils I presented. I couldn't see how that was wrong. Then I asked if I instead replaced neutral plasma consisting of ions and electrons with just ions, would the interaction with these H field lines and positive ion using Lorentz equation causing corkscrewing for individual ions somehow be any less valid. I just don't see how that could change a corkscrew fashion for a majority of the moving ions. Maybe I'm missing something here but you say there is no magnetic memory or sprialing for the vast majority of + charged ions of the Bussard polywell, in which case I believe you are saying no net magnetic memory over the sum of ions movements. I can agree to the sum of magnetic moments would be zero because there are as many ions coming in one direction spinning exactly opposite direction to those coming out. The individual ion would most likely not have a trajectory exactly parallel to the lines of H/flux, both incoming and outgoing to the center of the polywell and hence develop a corkscrew pattern and its own individual magnetic memory/moment. Even the slightest angle of trajectory (momentum) to the flux lines would cause this Lorentz spiral. Any + ion that went into a spiral would have magnetic memory and interact with the external H field. So here I am thinking again about this whole thing and changing from a neutral plasma to a + ion moving in and out of the Polywell, but still coming to the same conclusion that its interaction to those magnetic fields and flux lines will have to cause a majority to spin in corkscrew fashion. And if so they will interact with the external magnetic field lines just as I hypothesized. I do understand however that the sum of net magnetic fields from corkscrew motions could sum to zero as the + ions coming from the other directon and their own corkscrewing magnetic moment would cancel the other direction, that still would not mean though that the individual ions don't have memory and interact with the H field. More importantly that they would be influenced like tracks in alignment to their own magnetic spiral moment to those of the external H/flux field lines.

Regards,
Rod

hanelyp
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Re: Aviation Week on the Lockheed Skunkworks CFR

Post by hanelyp »

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.
It helps a lot if, unlike the tokomak, the magnetic field can contain plasma at near beta=1 and doesn't suffer from turbulence related to the field weakening when the plasma pushes it out of nominal position. You still need a magnetic field several gyroradius thick between the plasma and the first wall.
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RodCarlson
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Re: Aviation Week on the Lockheed Skunkworks CFR

Post by RodCarlson »

"It helps a lot if, unlike the tokomak, the magnetic field can contain plasma at near beta=1 and doesn't suffer from turbulence related to the field weakening when the plasma pushes it out of nominal position. You still need a magnetic field several gyroradius thick between the plasma and the first wall."


I understand that to be true and one thing that is rarely discussed is the larger picture of what really determines breakeven in energy production of fusion. As far as electric heaters for my house in the winter I'd be very happy with one that consumed 1000W of electric but put out 1100W of heat. Heck I'd even take a fusor heater that gave me 1W of extra heat for the 1000W of power input, because its all going to the same purpose of heating up the ambient temperature anyway, assuming the source of heat isn't deadly neutrons :) . But when it comes to converting heat to work in the conventional thermodynamic steam-dynamo you are limited to a maximum of the carnot cycle efficiencies which I believe is (TH-TL)/TH where TH is the superheated steam temperature to the turbine and TL is the resevoir or ambient temperature sink. Generally in thermodyamic classes and the temperatures of typical steam turbines and ambient temperatures you are looking at around ~30% real conversion efficiency (not Carnot which is usually higher). So that means that for a fusor to breakeven it would have to produce on the macro level 1/.3=3.33 or minus the original useful energy used of 1 an increase of 2.33 of heat energuy or at least 230% more heat then it uses in useful work energy (electricity and assuming you can keep that converted work heat as thermal energy to be converted to work also). But you hear the physicist saying all the time they could make a go at it with a 10% extra heat creation fusor conversion, which is true if you and only if you can raise the TH (even while TL resevoir stays the same) of the furnace box. I've always thought it strange in fact that really the carnot cycle isn't going to limit you to 30%, what is going to limit you is the highest you can get the TH of the fusor furnace box. Well practically speaking you are going to be limited to say the superheated water temperature if you use a steam turbine, and that is limited to how much pressure you can handle in the pipes in superheated steam.

But outside of that Carnot has no limit of efficiency as long as you keep raising the TH. And this TH in a coal burning plant is kind of limited by the fact that alot of useful heat goes up the smoke stack, with cool amibient oxygen/air displacing the wasted and unused exhaust. But if you could place the fusor furnace in an adiabiatic (totally thermally insulated) shell that allowed no heat to transfer through its insulated walls, then the TH could get as high as you want before allowing work to be generated from the extra high temperature of the TH furnace box. So its also about keeping all the energy in (adiabatic) at the macro level as much as keeping the losses low in the plasma, that determine breakeven of a fusion power plant. Neutrons and radiative energy (gamma, Xrays) that escape our theoretical wishing to be adiabiatic walls are really just an example of an un-adiabatic un-ideal furnace box.

I did notice that the Lockheed patent specifies a neutron absorbing shell that also breeds more fuel, but it seems to me that alot of the kinetic energy (potential heat energy) of a neutron that could otherwise be used for heating the TH in the furnace would be converted to internal energy of the new atomic structure that absorbes that neutron, not necessarily a form of usable heat energy (as in possibly endothermic). I suppose if I used a fissionable jacket then the absorbtion of the neutron could be very exothermic though. It probably isn't a big deal because fission reactors absorbs neutrons in heavy water just fine and release their kinetic energy as heat, but here again we aren't talking razor thin requirements to reach Carnot efficiency if you can only get a 10% increase of power from that used. 10% increase in output of heat from used useful work energy (electricity that ultimately also gets conserved and converted to heat) would mean that you'd need a conversion (carnot efficiency) of 90.9% just to break even in an ideal Carnot cycle. Given a carnot cycle of 90.9% you are looking for a TH/TL (in Kelvin) ratio of about 10.98. And assuming that a TL of room temperature of ~25C=298K that means a TH of 3272K or in Celsius how about a blistering 3000C and 5432F in the TH furnace, just to break even. That seems like an advance alien generator to me. Unless I'm reading the 10% increase incorrectly from what I heard about Lockheed's increase? Who know maybe they said they are only 10% from breakeven which would make a lot more sense. Ok where are the Q-tips, I'm going to go read it again somewhere on google, unless someone else can point out my mistake or misunderstanding. Granted a 10% increase of energy from useful base would still be a huge accomplisment when I think the best Farnsworth was a .01% increase in energy.

All this leads me to believe that 10% increase would be an amazing accomplishment, but unless I'm reading things wrongly (which is always possible), I wouldn't expect to have a fusor in your neighborhood block anytime soon producing home power. Solar energy is pretty practical form of fusion energy though and its abundant by about 1KW/m^2 on average. I'd be pleasantly surpised if I heard all this stuff wrong and it was true they would be able to power entire fleets of ships off it. I'm the optimist always and I never give up on the hope and dream though. And I like what I'm hearing from Lockheed.

What could really throw things off though is if somehow the jacket that was used to absorb neutrons was fissionable exothermic. Then it could be possible I suppose to get with a hybrid fusion/fission reactor something that would put out enough power for real applications?

I know many on here are more hesitant then me to believe that compact fusion can be done. To me nothing except trying to go faster than the speed of light, evading taxes, or escaping death eternally are impossible. It seems to me the optimists who keep the faith and believe all things are possible with enough work are the ones who win. Truly the man who gets the prom queen is usually the one who thinks he can. I believe the Lockheed team have something good going here and I believe its very easy to convince ourselves pessimistically based on previous attempts or knowledge that something is impossible, when it could be as simple as a change of a single overlooked variable that changes everything.

Regards,
Rod
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