No news is good news?

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

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joedead
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No news is good news?

Postby joedead » Mon Apr 13, 2009 12:50 pm

It's been kinda slow here for awhile now. Has anyone heard from Dr. Nebel? I imagine not hearing from him is a good sign; he's busy and doesn't have time to argue nuances on the forum. Even if it's a good sign, I'm still dying to hear about any progress that might be happening this year.

Any gossip?

Aero
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Postby Aero » Mon Apr 13, 2009 1:14 pm

Dr. Nebel posted a few comments on the theory forum last week. They include some interesting new information. See:
http://www.talk-polywell.org/bb/viewtopic.php?t=1211&postdays=0&postorder=asc&start=15 starting on page two.
Aero

joedead
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Postby joedead » Mon Apr 13, 2009 1:22 pm

Thanks Aero, I missed that.


:)

Barry Kirk
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Postby Barry Kirk » Mon Apr 13, 2009 8:54 pm

I've haven't been watching this forum for about 2 months, but from what I seem to remember,

1) DT with Bussard no problem.
2) DD with Bussard fairly safe, but a lot of engineering.
3) PB11 may not be possible.

Is that still the way people read things? Or is it looking better for PB11 at this point?

MSimon
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Postby MSimon » Mon Apr 13, 2009 10:03 pm

Barry Kirk wrote:I've haven't been watching this forum for about 2 months, but from what I seem to remember,

1) DT with Bussard no problem.
2) DD with Bussard fairly safe, but a lot of engineering.
3) PB11 may not be possible.

Is that still the way people read things? Or is it looking better for PB11 at this point?


I'd say that was a fair cop.
Engineering is the art of making what you want from what you can get at a profit.

Professor Science
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Postby Professor Science » Mon Apr 13, 2009 11:42 pm

What's this business about the bulk of the alpha's leaving through cusps? if it's not a uniform spherical ejection doesn't that drop cooling of the mag coils considerably?
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Professor Science
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Postby Professor Science » Tue Apr 14, 2009 12:17 am

What's this business about the bulk of the alpha's leaving through cusps? if it's not a uniform spherical ejection doesn't that drop cooling of the mag coils considerably?
The pursuit of knowledge is in the best of interest of all mankind.

KitemanSA
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Postby KitemanSA » Tue Apr 14, 2009 12:32 am

Except for hte general question of whether this thing will work at all, why is bB11 that much more in question?

HF Fusors run at 100+ keV all the time, no? That is the general level needed for pB11, so what is the difference?

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Postby MSimon » Tue Apr 14, 2009 2:03 am

KitemanSA wrote:Except for hte general question of whether this thing will work at all, why is bB11 that much more in question?

HF Fusors run at 100+ keV all the time, no? That is the general level needed for pB11, so what is the difference?


It is not a matter of getting pB11 to fuse. The problem is sputtering and heat load caused by the alphas which will be more severe than with other fuels.
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TallDave
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Postby TallDave » Wed Apr 15, 2009 12:01 am

Professor Science wrote:What's this business about the bulk of the alpha's leaving through cusps? if it's not a uniform spherical ejection doesn't that drop cooling of the mag coils considerably?


I was VERY excited to hear this, because it not only mitigates the alpha sputtering problem that seemed like a major hurdle, it also makes the first-wall problem considerably easier.

Previously, I'd assumed the alpha energies were too high for them to be affected much by the magnetic fields, but if they're making a thousand or so transits, that's quite a bit different. I should have known Rick and company had something up their sleeve there; every time he comments I learn something that changes my understanding of Polywell physics and the challenges involved. They've really done some serious analysis of these issues that we fumble with.
Last edited by TallDave on Wed Apr 15, 2009 12:08 am, edited 1 time in total.

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Postby TallDave » Wed Apr 15, 2009 12:07 am

Except for hte general question of whether this thing will work at all, why is bB11 that much more in question?


In addition to M Simon's point above, brem loss is more of a problem. Brem prevents tokamaks from ever getting anything approaching net power from p-B11 even if they could reach p-B11 temperatures, which they can't.

There's quite a bit on the challenges involved here:

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

IIRC Dr. Nebel has said there are ways a balance can be struck such that fusion gains are greater than brem losses.
Last edited by TallDave on Wed Apr 15, 2009 12:35 am, edited 1 time in total.

MSimon
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Postby MSimon » Wed Apr 15, 2009 12:23 am

TallDave wrote:
Professor Science wrote:What's this business about the bulk of the alpha's leaving through cusps? if it's not a uniform spherical ejection doesn't that drop cooling of the mag coils considerably?


I was VERY excited to hear this, because it not only mitigates the alpha sputtering problem that seemed like a major hurdle, it also makes the first-wall problem considerably easier.

Previously, I'd assumed the alpha energies were too high for them to be affected much by the magnetic fields, but if they're making a thousand or so transits, that's quite a bit different. I should have known Rick and company had something up their sleeve there; every time he comments I learn something that changes my understanding of Polywell physics and the challenges involved. They've really done some serious analysis of these issues that we fumble with.


I always expected that there would be reduced alpha impingement on the coil "edges" due to the magnetic field. However, due to the "slope" of the containers at that point I did not expect the heat load improvement to be significant. Of course I was thinking fields in the 1T to 2T range. 10T may be the field strength where things get a lot better at the "center" of the coil containers.
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MSimon
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Postby MSimon » Wed Apr 15, 2009 12:24 am

In a word:

Deflector shields up.
Engineering is the art of making what you want from what you can get at a profit.

windmill
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Postby windmill » Wed Apr 15, 2009 3:45 pm

So does this mean that WB-7 was actually burning PB11 at some point, or are Dr. Nebel's statements about alpha channeling based on simulations informed by other experimental evidence? That would be a first, I believe, if a polywell were fusing aneutronic fuels.

D Tibbets
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Postby D Tibbets » Thu Apr 16, 2009 2:07 am

windmill wrote:So does this mean that WB-7 was actually burning PB11 at some point, or are Dr. Nebel's statements about alpha channeling based on simulations informed by other experimental evidence? That would be a first, I believe, if a polywell were fusing aneutronic fuels.


Good question. I'm guessing that only D-D fusion has been done, but this produces He3 and tritium fusion products with similar or greater kinetic energies than the alphas from P-B11. Weather there has been any measurements of these fusion products (other than neutrons) and thier distribution is unknown. Certainly helium plasmas have been used at the drive energies of the device (~10-20 KeV ?). The conclusions may be based purely on theoretical modeling, possibly supported by other research with various field pinches, acelleraters, etc. If the nubs or joints between the magnets have been noted to heat more than predicted that may be some indirect evidence ( though at microwatts output I doubt that it would be measurable).


Dan Tibbets


Dan Tibbets
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