Thank you.MSimon wrote: Indrek is a he.
Is anyone else on this forum able to do those analyses?MSimon wrote: He is on to other things.
Anyone??
Hello o o o .
Personally, I think the symmetry of the situation would make an octahedral polywell theoretically possible (but probably not ideal), even with opposite faces of of differing color.KitemanSA wrote:Good catch!! And I've been pushing an octohedron myself.blaisepascal wrote:On the other hand, the octahedron alone has the important all-even-vertex property that allows the polywell to work. Two-coloring the octahedron yields 4 faces of one color, 4 faces of the other color, but opposite faces of the octahedron will have different colors.
Here's what I don't like about this, and maybe someone can explain why it's wrong.If there is an "out" coil directly in front of the "in" coil, (read North and South if you wish) the field just continues through the second coil and you get a longer coil. There is no line cusp between them, but they sure as heck don't cancel.
Should have been rectified rather than just truncated IMHO.TallDave wrote: Tom Ligon's fancy WB-100 graphic for the space conference was a truncated dodec.
Where do you find this "requirement"?TallDave wrote:Could the requirement to have same-polarity sides facing have to do with balancing the forces between coils?
Sounds like a benefit, though not a requirement.TallDave wrote:With a bunch of 5-10T magnets, that seems like it would be a large engineering concern. If you've got a coil casing being pulled one direction while being pushed the same direction from the other side, that's a hell of a lot of force on whatever holds the whole thing together.
A cuboctahedron and a rectified cube are the same thing, and is the same thing as a rectified octahedron. The process of "rectification" for a polyhedron is done by finding the midpoint of each edge and using those points as the new vertex set. By construction, each vertex of a rectified polyhedron is of degree 4. The original vertices and edges are completely eliminated in rectification.TallDave wrote:It's interesting, I've seen WB-6 called a truncube, rectified cube, and cuboctahedron. Of course they're all close to the same thing, it's just a question of how you expand the truncated corners.
I believe you are wrong, as the truncated dodecahedron pictured on that page has odd degreed vertices, and thus are unsuitable for a polywell according to Dr. Bussard's writing.Tom Ligon's fancy WB-100 graphic for the space conference was a truncated dodec.
http://en.wikipedia.org/wiki/Truncated_dodecahedron
I don't believe there is such a requirement, except for potential engineering issues like you state. But even then, the symmetry of the situation tends to balance forces out.Could the requirement to have same-polarity sides facing have to do with balancing the forces between coils? With a bunch of 5-10T magnets, that seems like it would be a large engineering concern. If you've got a coil casing being pulled one direction while being pushed the same direction from the other side, that's a hell of a lot of force on whatever holds the whole thing together.
It will, except for the gyro-motion. When it reaches the end (the second coil) it will try to transit the point cusp there and will either make it or be reflected back depending on how far away from the axis it is and how tight the pinch. No?TallDave wrote: Hold two identical bar magnets, N facing S, and put a piece of iron in the exact middle between them. Which way does it go? Well, it goes nowhere; the forces cancel so there is no force on the iron. Isn't that what's going to happen to an electron, too? It seems like it should go streaming through instead of being diverted at right angles to the coils.
The cusps got field! Heaps o tight field. (Except for the "funny cusp".) An electron headed outward from the axis along the plane of symmetry toward the line cusps may be gyratin like mad due to the field, but if the lines keep heading out straight, it'll just follow them out, just like an electron on the axis in the first example, unless the pinch is too tight. Or do I have to re-think this entire thing?TallDave wrote:Now, you can do the same thing with the magnets with same polarities facing, but the fields don't cancel there, they butt up against each other, forming a line cusp, and only the tiny area directly between them has no field.
As a matter of fact, you are both correct. The graphic in Tom Ligon's ISDC presentation did use decagonal coils instead of pentagonal, which would have produce strong line cusps between the adjacent sides of the decagons, and probably wouldn't have been as good a Polywell as one would want. But man is it PURDY!blaisepascal wrote:I believe you are wrong, as the truncated dodecahedron pictured on that page has odd degreed vertices, and thus are unsuitable for a polywell according to Dr. Bussard's writing.TallDave wrote: Tom Ligon's fancy WB-100 graphic for the space conference was a truncated dodec.
http://en.wikipedia.org/wiki/Truncated_dodecahedron
Indeed.KitemanSA wrote:]As a matter of fact, you are both correct. The graphic in Tom Ligon's ISDC presentation did use decagonal coils instead of pentagonal, which would have produce strong line cusps between the adjacent sides of the decagons, and probably wouldn't have been as good a Polywell as one would want. But man is it PURDY!
I wasn't able to find Tom Ligon's presentation easily. Do you have a link to it?
I'd love to see the equivalent graphic with bowed pentagonal plan form magnets. That should be fine art!
Here's a link. It's the little PPT icon on bottom right, p24.I wasn't able to find Tom Ligon's presentation easily. Do you have a link to it?
I'm not sure what you mean by this. Can you cite a reference for Bussard on that, or explain why this matters? My understanding was it just needed an even number of sides at a vertex.I believe you are wrong, as the truncated dodecahedron pictured on that page has odd degreed vertices
Thanks.TallDave wrote:Here's a link. It's the little PPT icon on bottom right, p24.
I believe we are in agreement. The "degree" of a vertex is the number of edges incident at that vertex. Equivalently, it's the number of faces meeting at that vertex. Bussard said that for polywell to work adjacent faces on the polyhedron had to have opposing magnetic fields (i.e., N adjacent to S, not N adjacent to N or S adjacent to S). In order for that to work, the faces around each vertex had to be alternating N/S. Therefore there can't be an odd number of faces around each vertex. Therefore, all vertices have to be of even degree.I'm not sure what you mean by this. Can you cite a reference for Bussard on that, or explain why this matters? My understanding was it just needed an even number of sides at a vertex.I believe you are wrong, as the truncated dodecahedron pictured on that page has odd degreed vertices
Right, and that field null is called the "funny cusp". As long as there is nothing in the way of said FC, Recirc (a.k.a.) oscillation of the electrons should prevent excessive losses.Art Carlson wrote:Discussing the problem in terms of polyhedra that have vertices of an even degree is elegant, but a bit beside the point. If the magnetic coils are really laid along the edges of a polyhedron, then the vertices will be field nulls and leak like sieves.
Not sure what you are driving at here unless you mean that with a pair of real and a pair of virtual coils, you will get a modifed line cusp that is related in length to the area over which the two real coils parallel each other. The shorter the span, the shorter the cusp.Art Carlson wrote:I think we agreed that the coils cannot touch, so there is no equivalence between real coils and virtual coils.