magrid configuration brainstorming

[rjaypeters]

I call this a "woven" magrid concept. Inner coil:



Inner, middle and equatorial coils:



Inner, middle and equatorial coils (top view):



Still have the polar situations to deal with, but I figure a single coil, oriented perpendicular to the axis, above each pole should close those holes. If one wanted thrust out of a pole, just reduce the magnetic field from that polar coil (but not enough to endanger the coil itself).

[rjaypeters]

Around Thanksgiving I made the so-called "interdigitation" concepts. happyjack27's triangular concepts and the "woven" design reminded me of the interdigitation work. Here is a single-coil interdigitation:





There are still the problems and opportunities of the poles.

[rjaypeters]

Something a little simpler:

[rjaypeters]

And then there is the dual hexagonal pyramid, Tombo'd:







In Imaginatium's honor, I might get around to putting structural supports on it.

[happyjack27]

problem w/the square tiling woven ones is that u cant do an alternating north in, north out.

the trihexagonal tiling woven ones you can, but you can't have a simple coil topology of just intersecting longitudional coils, cause the hexagons have to be north in and triangles north out or vice-versa. meaning any longitudal coil will have to alternate current direction between line segments.

part of the beauty of triangular tiling is that it avoids both of these problems.

also the tiling can be made arbitrarily small. one could have a sort of "micro-grid", where each coil is composed of really a single thin wire. and the spacing could be made many times smaller than a single electron gyro-radii. also, such a distributed grid would make for a very effective heat sink for itself. that is, the heat production would be spread out very evenly and surrounded everywhere by vacuum. that is, you get nearly maximal passive cooling for free.

it would look something like this:



and could be constructed iteratively from one of the base polyhedra listed in my previous post like so:

[happyjack27]

interestingly, you'd only have to put current in a few of the wires (e.g. just the base polyhedron), and the mag fields should induce the correct current flow in the entire grid. even if the wires touch. interesting to see what such a superconducting wire sphere would do by itself - that is, with no energy input. or maybe just in the presence of a few external electromagnetic fields to charge it up. (in this way it would act sort of like a transformer.)

[rjaypeters]

also the tiling can be made arbitrarily small. one could have a sort of "micro-grid"...

I like this idea. My next thought is the structural support for the micro-grid wires will also need to be similarly widely distributed. Will the wires be strong enough to hold the required shape without reinforcement? And lots of distributed supports from the chamber walls?

It may be the distributed grid can, through Buckminster Fuller's tensigrity concepts, resist the magnetic (major) and gravity (minor) forces.

If lots of smaller supports from the chamber walls are required, I think this concept should be called the "sea urchin".

[happyjack27]

also the tiling can be made arbitrarily small. one could have a sort of "micro-grid"...

I like this idea. My next thought is the structural support for the micro-grid wires will also need to be similarly widely distributed. Will the wires be strong enough to hold the required shape without reinforcement? And lots of distributed supports from the chamber walls?

It may be the distributed grid can, through Buckminster Fuller's tensigrity concepts, resist the magnetic (major) and gravity (minor) forces.

If lots of smaller supports from the chamber walls are required, I think this concept should be called the "sea urchin".

i can imagine 5 scenarios:

1. the magnetic fields have no net global stress/strain effect
2. the magnetic fields cause it to "puff out"
3. the magnetic fields cause it to "scrunch up"
4. the magnetic fields cause it to destabilize - making parts of it contract and parts of it puff until it's an unholy combination of a wrinkled piece of paper and a balloon animal.
5. the magnetic fields cause it to stabilize.

of these, 2 and 5 would be ideal, obviating the need for anything but a minimal support structure, 1 would be just fine i suppose, while 3 and 4 would be problematic, requiring extensive support.

[happyjack27]

also, electrostatic forces due to an imbalance in the charges -- such as a small excess of electrons in the plasma and a small positive charge on the grid -- would impose net contractive or expansive pressure on the grid. (in this example, net contractive.)

and seeing that we have alternating in-out, i think the net force would be de-stabilizing, particularly in the form of what i'd call a "stellating" instability, like shown here.

however, since the grid is all similarly charged, it would repel itself, resulting in a "puffing out". this can help counter-act the stellating instability produced by the mag fields, as well as the attraction to the net-negative core.

[rjaypeters]

On the cooling front: cryo-cooling vacuum chamber walls is twentieth-century tech. Passive cooling of the grid wires would have a pretty good heat sink.

[rjaypeters]

however, since the grid is all similarly charged, it would repel itself, resulting in a "puffing out". this can help counter-act the stellating instability produced by the mag fields, as well as the attraction to the net-negative core.

So the trick would be to find the balance.

[happyjack27]

come to think of it, a little stellation might not be all that bad - it would improve recirculation and probably produce smoother internal mag fields - thus enhancing the wiffle-ball effect to boot.

(edit) in effect stellation would be pushing the configuration sort of in the direction of a "winged hanlyp".

[rjaypeters]

Those geometrical stellations look like a lot of fun to model.

As you note, of our work so far, only hanelyp's "winged" has had coils away from the quasi-spherical surface described by all the other coils. Do you want to go further in this direction?

Are we discussing the 2nd, 3rd or 4th generation Bussard/Nebel fusion generator?

[happyjack27]

Those geometrical stellations look like a lot of fun to model.

As you note, of our work so far, only hanelyp's "winged" has had coils away from the quasi-spherical surface described by all the other coils. Do you want to go further in this direction?

Are we discussing the 2nd, 3rd or 4th generation Bussard/Nebel fusion generator?

frankly i dont feel like sim-ing anymore. i think we've gotton about all the info we can get out of it. i know what a micro-grid's core would look like: much bigger, (less centrally focused) but much more spherical, so the confinement would still be good.

that seems like the trade-off when u go to higher order polyhedra: the ratio of the wiffleball radius to magrid raidus is bigger, so you dont have as large of an electrostatic gradient (potential well) to focus and accellerate the ions. i suppose once you reach optimal kes for fusion cross-section, confinement becomes more important than kinetic energy. so maybe in larger machines, it'd be just as well.

so though i'd say i'd be interested in simulating a spherical wireframe like i posted above, i wouldn't be interested enough to actually do it.

on another note... there's only a little over a month before emc2 is scheduled to finish testing of the wb-8!

[rjaypeters]

Dual hexagonal pyramids Tombo'd with extensions:





Your objections to this geometry (top view central detail):



you may take as stipulated.