## Is There an Optimal Size for Magrid Casings?

Discuss the technical details of an "open source" community-driven design of a polywell reactor.

Moderators: tonybarry, MSimon

tombo
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Location: Washington USA
The details of the X-Cusp field above were done on a planar model ie 2D.
I am now working on modeling it in 3D. Kiteman thought it would squeeze the field tighter inside the sphere of the Magrid and avoid field nulls at some distance inside the Magrid.
Here is where I am on the 3D Bfield model of the X-Cusp configuration.

You can see the fields coming out the triangular coils and the X Cusp rectangle and going in through the square coils.

Next I plan to zoom in on the X-Cusp area and try to:
1. show layers of field vectors roughly parallel to the sphere to see if there is a surface without a null field and field reversal zone
2. show close those layers get to the radius of the Magrid before seeing field nulls.
3. find and map the field reversal zones.
4. check for other issues.
-Tom Boydston-
"If we knew what we were doing, it wouldn’t be called research, would it?" ~Albert Einstein

charliem
Posts: 164
Joined: Wed May 28, 2008 8:55 pm
tombo wrote:Kiteman thought it would squeeze the field tighter inside the sphere of the Magrid and avoid field nulls at some distance inside the Magrid.
Are you sure about that, I think there are 8 lines of null field coming out from the core, and going all the way outside the magrid. What with them?

Cut design though.

KitemanSA
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charliem wrote: Are you sure about that?, I think there are 8 lines of null field coming out from the core, and going all the way outside the magrid. What aboutwith them?

Cute design though. {editorials by me}
I am responding to my understanding of the prior post, as shown.

If this were in fact a polywell with funny cusps, I think your vision would be correct. However, this is a minor modification that has null fields only inside the conductors like all electro-magnets, and along the "effective center of current". That ECoC lies only in the triangular and square magnets seperate and kind of peter out near the line of symmetry between the paired square magnets.

OF course, we may both be wrong and there may be 8 PAIRS of nulls locate where your 8 nulls are.

Ignoring the wiffleball effect for a second, there would be a line of STRONG field along the line that would otherwise go out the funny cusp, and that strong field is the same direction as the triangular magnet field.

charliem
Posts: 164
Joined: Wed May 28, 2008 8:55 pm
Sorry for the mistakes in my writing Kiteman.

This design is structurally stronger, and quite elegant, but, as you yourself say, creates points of null field in the space between the triangular and square magnets (moreover, in those regions the magnetic field in-out direction is not constant).

That at least suggests the possibility of heavy electron leaks through those regions, but who knows. Good Polywell simulation software would be such a help for situations like this...

KitemanSA
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The electrons will certainly leave the core thru these cusps, but then they will be returned thru these hole because of the MaGrid charge. Only the upskattered will be lost to the wall, but that merely returns the energy to the system.

MSimon
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KitemanSA wrote:The electrons will certainly leave the core thru these cusps, but then they will be returned thru these hole because of the MaGrid charge. Only the upskattered will be lost to the wall, but that merely returns the energy to the system.
But the energy is returned as heat.
Engineering is the art of making what you want from what you can get at a profit.

KitemanSA
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MSimon wrote:
KitemanSA wrote:The electrons will certainly leave the core thru these cusps, but then they will be returned thru these hole because of the MaGrid charge. Only the upskattered will be lost to the wall, but that merely returns the energy to the system.
But the energy is returned as heat.
Only the excess, but the main portion will be returned usefully. By that I mean the energy originally provided by the MaGrid to the electron will be returned to the MaGrid.

tombo
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Joined: Fri May 09, 2008 1:10 am
Location: Washington USA
Ummm
Maybe I'm being obtuse but...

The grid is positive.
The electrons are attracted to it and neutralize this charge.
This returns energy to the system how?
-Tom Boydston-
"If we knew what we were doing, it wouldn’t be called research, would it?" ~Albert Einstein

93143
Posts: 1131
Joined: Fri Oct 19, 2007 7:51 pm
Electrons lost to the electron guns/trap grid will return the energy added by the magrid to the power system, because they've wound up back at their starting potential.

Each electron lost to the wall in a p-¹¹B reactor will waste about 1.88 MeV, plus the magrid-trap grid potential difference, plus the upscatter energy. Perhaps this is a good reason to have the electron guns be deeper in the well than the trap grid...

KitemanSA
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