magrid configuration brainstorming

[KitemanSA]

Is this an issue?

Good question. At the present only the MPGs have had this plan-form. I have read that they were amongst the only other machines to do fusion, so perhaps the condition is of LESS importance in this design than in a round plan-form machine like WB6.

Personally, I like the bow-legged real-real version of this design. This one! Kudos to tombo! marvelous graphic!

[chrismb]

If I have it right then the square faces of the cuboctahedron would represent pole faces of the six real magnet coils and the triangular faces would be the virtual pole faces. In this case you would want all six real coils to have the same polarity pointing toward the core. Am I right about this?

So, is he right about this? This is what I was trying to say above, before I was told I am confused. I am.. indeed....

[KitemanSA]

If I have it right then the square faces of the cuboctahedron would represent pole faces of the six real magnet coils and the triangular faces would be the virtual pole faces. In this case you would want all six real coils to have the same polarity pointing toward the core. Am I right about this?

So, is he right about this? This is what I was trying to say above, before I was told I am confused. I am.. indeed....

Randy had shown a vertex of an octagon with 4 real magnets of alternating polarity, which is what it should be. You opined that they were all supposed to be the same polarity. I stated that you were incorrect.
Looking at a vertex in the rectafied cube, the square faces alternate with the triangular. The squares have the same polarity but are opposite the polarity of the triangles.
When using an octahedron ALL faces are triangular so the alternating faces must have alternative polarity, NOT the same polarity you suggested. Clear?

[Randy]

Is this an issue?

Good question. At the present only the MPGs have had this plan-form. I have read that they were amongst the only other machines to do fusion, so perhaps the condition is of LESS importance in this design than in a round plan-form machine like WB6.

Personally, I like the bow-legged real-real version of this design. This one! Kudos to tombo! marvelous graphic!

Yes – yes, I see what you’re saying: “Why not make the virtual poles (about the triangular faces) real coils as well?” ‘tombo’ does indeed make good 3-D graphics!

As I mentioned earlier my concern about the B-field through the triangular faces of the cuboctahedron being almost double that through the square faces. I thought that this phenomenon might introduce more inductance into the electric circuit of the magnet coils.

Coil inductance is a big issue with prototype magrid configurations because they will almost always be of the pulsed current type (large capacitor-bank discharge test platforms).

This led me to favor the octahedron (eight-coil) configuration. But I did a quick double-check analysis and discovered that even though the B-field through the triangular surfaces is almost double that through the square faces, this does not affect the overall inductance of the electric circuit. My reasoning follows:
Total coil flux linkage (flux) = B * Area.
L(inductance) = Nturns * total coil flux linkage (flux) / i.
My previous analysis shows that for the triangular faces the B-field magnitude increases in the same proportion as the decrease in the area of the triangles as compared to the total surface area of the cuboctahedron. Thus causing no net change in the [Total coil flux linkage (flux) = B * Area] through the triangular faces. Therefore the L(inductance) of the circuit is not affected by this phenomena.

This observation shows that (as far as electric circuit inductance is concerned) the six coil cuboctahedron square plan-form magrid configuration is likely a better design than an eight coil triangular plan-form octahedron configuration because it only features six coils, thus introducing less overall coil circuit inductance.

Kiteman, I definitely see why you like the bow-legged real-real design.

The KISS (Keep It Simple Stupid) paradigm has never failed me. So for simple prototype designs I believe the “squared” cuboctahedral design is the most desirable configuration to work with. It can’t be much more difficult to fabricate six square plan-form coil spools than six round plan-form coil spools. i.e., the six coil cuboctahedron square plan-form magrid configuration. As posted by you earlier:

…This is likely the best simple magrid configuration for prototype construction.
~Randy

[KitemanSA]

Personally, I like the bow-legged real-real version of this design. This one!
((See Color Image Above))
Kudos to tombo! marvelous graphic!

Yes – yes, I see what you’re saying: “Why not make the virtual poles (about the triangular faces) real coils as well?” ‘tombo’ does indeed make good 3-D graphics
...
Kiteman, I definitely see why you like the bow-legged real-real design.

Gorgeous, isn't it. It LOOKS like a fusion reactor. I sometimes expect the picture to spontaneously start generating neutrons!

The KISS (Keep It Simple Stupid) paradigm has never failed me. So for simple prototype designs I believe the “squared” cuboctahedral design is the most desirable configuration to work with. It can’t be much more difficult to fabricate six square plan-form coil spools than six round plan-form coil spools. i.e., the six coil cuboctahedron square plan-form magrid configuration. As posted by you earlier:
((See B&W Image Above))…
This is likely the best simple magrid configuration for prototype construction.
~Randy

To a point I agree. But I have a winding process that would make a minor variation of the tombo picture and it would be just about as easy to make as "mine" (i.e. Dr. B's).
I keep telling myself I am going to build one, but I can't find a chamber to test it in. I am not willing to build one myself because I live in a condo and have no room for it.

Does anyone have a chamber/power supply suitable for a 30cm Magrid like the tombo picture? I envision a 64 strand winding so the field would be about 1/3 the WB6 unless I added a coolant loop.

Chamber & power supply anyone? Dr. N., you could chime in too!

[ladajo]

Kite,
I like the picture too, but everytime I sit down and think about the field patterns, I think it will not shield properly at the triangle apex. As I wrap my head around the spcaing consideriations and filed interactions, it keeps seeming to me that an electron heating point will develop at the apex points.
I realize I can be all wet about this, but I can't get a grasp on it.

I believe that early designs (MPG?) follwed this proposed style, and that there were heating issues.

[KitemanSA]

Kite,
I like the picture too, but everytime I sit down and think about the field patterns, I think it will not shield properly at the triangle apex. As I wrap my head around the spcaing consideriations and filed interactions, it keeps seeming to me that an electron heating point will develop at the apex points.
I realize I can be all wet about this, but I can't get a grasp on it.

I believe that early designs (MPG?) follwed this proposed style, and that there were heating issues.

I'm not quite sure what you mean by the "apex points" so cannot respond regarding your concerns.

However, the MPG had metal at the Funny Cusp where this one has a hole (an "X Cusp"). If by "apex point" you mean those re-entrant corners around the "X Cusp" then I was under the impression that the issue had been laid to rest pending contrary analysis. Maybe not.

[ladajo]

Each half of the sphere has three square coils, and four triangles. My concern lays in the shape made where two triangles and two sqaures come together. The shape this gap makes and the field interactions at this point are what I am struggling with.

[icarus]

It LOOKS like a fusion reactor.

It looks like a cartoon toy-ball of tubes.

ladajo's got a point. That analysis of the fields around the 'funny-cusp' that you did on this thing was, shall we say, less than rigourous.

Haven't you just ended up sticking a load of material right where you least want it?

[KitemanSA]

Each half of the sphere has three square coils, and four triangles. My concern lays in the shape made where two triangles and two sqaures come together. The shape this gap makes and the field interactions at this point are what I am struggling with.

Tombo and I did some math on that in the "Is there an Optimal Size for a Magrid Casing" topic in the design forum a while back. My opinion was that the lateral field elements would successfully cover the issue and that if not, that particular area could be made "hole-ier" to eliminate the issue. TBD.

[KitemanSA]

It LOOKS like a fusion reactor.

It looks like a cartoon toy-ball of tubes.

Wow! Stop the presses! Icarus disagrees with me on something.
Oi, such a surprise this is!

ladajo's got a point. That analysis of the fields around the 'funny-cusp' that you did on this thing was, shall we say, less than rigourous.

You are invited to apply more rigour. My analysis showed enough for my purposes at this time.

Haven't you just ended up sticking a load of material right where you least want it?

No. All the material, AFAICT, is properly protected by magnetic fields. There is NO unprotected material except for the legs (which are actually shown substantially bigger than they need to be).

[icarus]

You are invited to apply more rigour.

Do it yourself. It is your brilliant idea after all.

Hint: no material is better than 'protected' material in this game.

[KitemanSA]

[/quote]

You are invited to apply more rigour.

Do it yourself. It is your brilliant idea after all.

I've done it at the rigour I needed. You are carping about it, you prove me wrong. else you are just uselessly carping. Oi, what a surprise!

Hint: no material is better than 'protected' material in this game.

You have to hold it together somehow. This does it with proteted material. No other way I've seen does. Unless of course you know of a magical way to withstand the multi-Tesla magnetic field forces with "no material"?

[WizWom]

You are invited to apply more rigour.

Do it yourself. It is your brilliant idea after all.

I've done it at the rigour I needed. You are carping about it, you prove me wrong.

Um, NO.
This is science, not law. You need to Prove your theory or design rigorously, with either a demonstration or mathematics.
And a mathematical proof needs to have a physical demonstration for it to be acceptable.

Thank you for playing, please go back to freshman Physics before trying again.

[icarus]

You are carping about it, you prove me wrong. else you are just uselessly carping.

Nice, anybody who challenges your design speculations is "uselessly carping" ... I bet you are a real treat to work with ... fear not, back to your usual mutual back-scratchin' and hierarchical grooming, I'll just leave this, yet another sacred cow, alone as well.