EMC2 has published a polywell preprint on arXiv

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

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bcokeley
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Re: EMC2 has published a polywell preprint on arXiv

Postby bcokeley » Sat Jun 07, 2014 12:23 pm

I've been more or less lurking here since 2008. Is this the good news I was always hoping for? Does this news mean Polywell works? Has Dr. B original claim been confirmed or is this some encouraging news after a long information drought?

-Bryan Cokeley

mvanwink5
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Re: EMC2 has published a polywell preprint on arXiv

Postby mvanwink5 » Sat Jun 07, 2014 1:58 pm

It means polywell works. The next question is what is the next test step? That would be to gun up for WB-8.1, then "Katie, bar the door."
Near term, cheap, dark horse fusion hits the air waves, GF - TED, LM - Announcement. The race is on.

mvanwink5
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Re: EMC2 has published a polywell preprint on arXiv

Postby mvanwink5 » Sat Jun 07, 2014 2:42 pm

DTibbets comment is very interesting,
Thus, not only high Beta/ Wiffleball confinement was demonstrated, but also densities that allow for useful fusion output in small machines.


* I wonder how small? On the other hand on a Navy ship peak power is important, less for electric utility power as the grid and attached rotating machines handle short peaks. I wonder what the output would be for WB-8 size with D-T?

* I can't believe the Navy would drop this contract at this point, but it seems to have done that, short of WB-8.1. :roll: It would seem that bodacious guns plus WB-8 size would be a bit more than planned, still... what is a rail gun powered with Obama solar cells? Oh, that is right, wind turbines on a ship (or sub), of course, what was I thinking.

* The starting package is large even if it is a short duration pulse power, capacitors, baby!

* Coil mounting from the backside, no coil to coil nubs, is what was expected.

* Outside of the elephant guns, the size is doable for an amateur? Diagnostics was essential here, that is another factor.
Near term, cheap, dark horse fusion hits the air waves, GF - TED, LM - Announcement. The race is on.

mvanwink5
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Re: EMC2 has published a polywell preprint on arXiv

Postby mvanwink5 » Sat Jun 07, 2014 2:50 pm

For startup to jump to beta = 1, what about firing a pellet and zapping it once inside the coils with a laser to completely ionize it, plus smaller guns to create the right excess electron population? Just an engineer's wild thinking here. That would be doable even for an amateur (with talent.)

Maybe with current guns EMC2 could even reach beta = 1 start up for WB-8 with this approach?
Near term, cheap, dark horse fusion hits the air waves, GF - TED, LM - Announcement. The race is on.

TallDave
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Re: EMC2 has published a polywell preprint on arXiv

Postby TallDave » Sat Jun 07, 2014 3:10 pm

BTW as others have pointed out, this doesn't prove Polywells are a viable path to economic fusion power, it just means they crossed another significant hurdle. It's still hard to know for sure what losses will look like in reactor-sized machines, to say nothing of the electron optics. A demo reactor does seems more within reach now, though.

This strikes me as something of a "battlespace preparation" paper, getting the scientific community used to the idea that Polywells are out there and the wiffleball effect is real, which as Rick once noted is the most critical factor. That was one reason it was useful to have Art's take, even though most everything he surmised re Polywells was wrong it was probably representative of the mainstream (i.e. tokamak/MCF) fusion community view.

Maybe as much as anything else it's just great to see so much accurate information about Polywells in one place. It's really hard for people to string together more than three sentences on the subject without making major errors.
n*kBolt*Te = B**2/(2*mu0) and B^.25 loss scaling? Or not so much? Hopefully we'll know soon...

mvanwink5
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Re: EMC2 has published a polywell preprint on arXiv

Postby mvanwink5 » Sat Jun 07, 2014 3:19 pm

Small machines are the hardest for polywell (opposite of ITER), and diagnostics tell the story.
Near term, cheap, dark horse fusion hits the air waves, GF - TED, LM - Announcement. The race is on.

GerardFianen
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Re: EMC2 has published a polywell preprint on arXiv

Postby GerardFianen » Sat Jun 07, 2014 6:21 pm

Wow, did they test our patience. Following this for so many years.. Great news ! Very much looking forward to further developments. Curious to what some of the experts active here on this forum think of this report.

P.S. Hope all the rossi related and LENR stuff can be left to other (far better suited) websites and forums. Or at least be moved to off-topic. This forum and it's wealth of Polywell expertise deserves it.

Tom Ligon
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Re: EMC2 has published a polywell preprint on arXiv

Postby Tom Ligon » Sat Jun 07, 2014 8:31 pm

Answering a few random comments and questions as best I can ...

Tested our patience. I've been trying to warn you guys that Jay Park is a patient fellow, intent on doing things right.

Proves Polywell works. Well, confirms a key point in the theory that improves the power balance by several orders of magnitude. The rest of this still has to be right as well, but I feel better about it now.

Navy needs to fund it. It needs to be funded, but exactly who should do it is still a good question. You already know this thing vanishes into the mist when the Navy funds it. They've been a blessing, but a frustrating one for those of us eager for news.

Amateur could do it. That's been tried. You can make a small fortune that way, by starting with a LARGE fortune. I personally think it could be done but it would be a big help if that amateur were a billionaire. One could probably make a credible WB8-ish machine for a couple of million bucks, but that's just a toy. Mind you, if I won a large enough lottery, I'd be doing it. Now, let's see, how much of a magnet could I drive with that big power supply I picked up from the Prometheus Fusion Perfection yard sale?

The "pop the clutch" analogy is pretty good. And rev the engine first ... the conditions needed to instigate a proper wiffleball are apparently a bit steeper than first modeled, and it is quite helpful to have some data to tell just what it takes. Building a big machine and then trying to sneak up on a wiffleball from the bottom using inadequate equipment is a terrible waste of time and money.

Aero
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Re: EMC2 has published a polywell preprint on arXiv

Postby Aero » Sat Jun 07, 2014 9:18 pm

Way back when ... we were designing the cooling system for the superconductor coils. Did we ever consider lining the cooling channels with thermoelectric generators? There is quite a temperature drop between coolant channels. Is there a thermoelectric generator material that would operate at those temperatures?

As I recall we had 3 levels of coolant flow from the torus outer wall to the superconductor wall. Even if only 3-5 % of the heat energy across each boundary were converted to electricity we would have a nice boost in power out of the Polywell generator from waste heat.
Aero

mvanwink5
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Re: EMC2 has published a polywell preprint on arXiv

Postby mvanwink5 » Sat Jun 07, 2014 10:01 pm

Aero, wouldn't that cause heat transfer, the opposite of what we are trying to do (insulate one layer from the other)?
Near term, cheap, dark horse fusion hits the air waves, GF - TED, LM - Announcement. The race is on.

Aero
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Re: EMC2 has published a polywell preprint on arXiv

Postby Aero » Sat Jun 07, 2014 11:04 pm

mvanwink5 wrote:Aero, wouldn't that cause heat transfer, the opposite of what we are trying to do (insulate one layer from the other)?


Don't know. My impression has been that thermo electrics act as insulators rather than conductors. I will have to visit Google to see what I can discover. Another question has to do with operation in a 7 T magnetic field. Will they even work in a strong magnetic field and will they mess up the containment field?

If I find something interesting I'll take this over to the "Design" forum.

By the way, 3 layers at 3-5% of the heat from D-T fusion should just about compensate for the cusp and Brem. loss energies. A nice contribution.
Aero

zapkitty
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Re: EMC2 has published a polywell preprint on arXiv

Postby zapkitty » Sat Jun 07, 2014 11:24 pm

Aero wrote:By the way, 3 layers at 3-5% of the heat from D-T fusion should just about compensate for the cusp and Brem. loss energies. A nice contribution.


... from a ~2GW neutron flux in a 2 meter cube?

The D-T is offered as a comparative example. Hypothetical, even :)

If such a rig were actually built I'd be curious as to if the neutron bombardment itself would cause a quench before the temperature spikes did...

Aero
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Re: EMC2 has published a polywell preprint on arXiv

Postby Aero » Sun Jun 08, 2014 1:33 am

Spent some time with Google. Per one report, Thermoelectric materials can generate electricity in a magnetic field, and in fact the field can increase the efficiency - but the details are absent. What orientation of the magnetic flux is used, for one?

Thermoelectric materials design try to increase heat insulation while increasing electrical conductivity. That is, increase heat insulation and decrease electrical resistance.

One device available on the market (there are a number of products available) can operate with a high side temperature of 800 deg. C. What wall temperature would the Polywell operate at.

To many questions outside of my field. I'm going to drop the subject for now.
Aero

Tom Ligon
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Re: EMC2 has published a polywell preprint on arXiv

Postby Tom Ligon » Sun Jun 08, 2014 3:20 am

We had a discussion here recently about improved thermoelectric materials. Common Peltier cooling modules work as TEGs at about 4% efficiency. The discussion pointed out a new type that might give 19%, which itself would be revolutionary, and then pointed to theoretical work on graphene TEGs that might hit over 60%.

TEGs work on heat flow and not temperature. Cryogenically cooled superconducting magrids would have vacuum breaks to insulate the cryo portions as much as possible, so one hopes the heat flow into the cryo portions is minimal. Likely there would be a water jacket just under the outer skin of the magrid to take as much heat load as possible off the cryo portions. There would be heat flow at the magrid surface but environment may not be ideal for thermoelectrics right there. But there's an opportunity at the outer chamber walls (they will be hit by lost particles), and that cooling fluid needs to dump heat somewhere. TEGs outside the chamber, if they produce the anticipated high efficiencies, might very well scavenge significant extra energy from the walls and cooling fluid radiators.

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Re: EMC2 has published a polywell preprint on arXiv

Postby D Tibbets » Sun Jun 08, 2014 4:18 am

Thermoelectric coolers/ heaters are fairly fragile. And as small thickness devices they are probably vulnerable to neutron bombardmant. In the paper exampe, with a 1 meter magrid diameter, the heat flux from bremsstruhlungwould be considerable. The heat flux from ExB drift electrons and ions may add up to several MW or possibly even several dozen MW of heating. The heating by perhaps ~ 1 GW of energetic neutrons would be the bigest contributor, depending on how transparent the magrid is to neutrons. Presumable it would absorb a fair amount with the water blankets, liquid helium or liquid nitrogen. I seriously doubt the magrid could long survive a thermal load of perhaps 10,20 or more MW per meter squared. M. Simon liked to quote 1-2MW/M^2 loads being reasonable. I don't think a 1 meter or even a 2-3 meter machine could tolerate over a GW of neutron energy, along with the perhaps ~ 100 MW of x-ray and charged particle heating. I think thermoelectric converters would be even more vulnerable to the proton recoiling and transmutations from the neutrons.

A 1 meter magrid Polywell might reach the predicted performance, but I greatly doubt it could endure for long (hours or days).

I speculate that the D-T reactor was presented because it gives the impressive small size from a physics standpoint and D-T fusion is the mind set of the vast majority of fusion / plasma physicists.

A very rough calculation of a D-D reactor may break even at a size of ~ 3 meters, B of 10 T and an input of 1 GW, and output of about a GW might actually be doable from an engineering perspective.

Note that this performance / breakeven is ~ 10 times worse than projected for WB100. What is different? That is hard to say as no numbers were provided about confinement, recirculation, confluence, etc. I assume that the scaling may be based on the test machine which was used to demonstrate Wiffleball formation. Performance in WB 6, 7, and 8 may be more enlightening, if it was presented.

To calculate D-D fusion I divided the D-T number by 100 for the smaller D-D cross section, then multiplied by ~ 27 for the 3 meter diameter volume increase and ~ 4 fold increase by using 10 Tesla. This makes up for the difference in the fusion cross section curve. Voltage may need to be increased some, or perhaps not if dominate beam- beam interaction is assumed. Using that assumption I think the example 60KV input might be enough- again with maintained 50% potential well efficiency. The increased size would increase input costs 9 fold. Then of course there is the smaller D-D fusion output per reaction. I'll conviently ignor that except to suggest that a significant portion of the deficit may be made up by jacket Boron 10 blanket, and recycling the H3, and reluctantly the tritium.

The saving grace of this approach may be that tritium production does not need to be at unity, which would be required for a dedicated D-T reactor, and very difficult to achieve due to the internal presence of a magrid before any possible lithium blanket. You could perhaps use a lithium salt in the water coolant, but this would still not be a "first wall" exposure to the neutron flux.

The numbers, while demonstrative of the approach, are painful. Better confinement such as that claimed for WB6, and recirculation, and better electron injection efficiency, and better potential well efficiency , some degree of confluence, and direct conversion can all significantly improve the picture individually, and together might make a profound difference. It is time for the physicists and the engineers to spend some real money addressing these issues.

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


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