Billy Catringer wrote:
ekribbs wrote: You missed the theme of this discussion. We were concerned with the electron losses at the "nubs" that hold the magnet coils together, which as everyone agreed were in tension due to the radially outward magnetic forces.
Tom Ligon and I suggested removing the "nubs" to really eliminate the electron losses. Consequently, there would be nothing to hold the magnets together in the current arrangement of WB-6/7. We suggested that for a future re-design, an insulated pipe truss attached to the inner pressure vessel walls could be employed to support each magnet separately. MSimon wants to build an inner structural cage instead of going directly to the pressure walls to shorten the length of the truss/towers. I suggested a radial configuration of the magnets with two co-linear magnets on the central "axis" to close out the magnetic bottle to be more conformal to a cylindrical pressure vessel.
Can anyone tell us what the ID of the vessel needs to be to hold a magried made up of 2 meter coils or Bitter Plates? The pictures I have seen suggest that at least one magnet diameter between the magrid and the vessel walls is necessary. However, with magnets this size we are dealing with magnetic fields that are much stronger than those developed by WB6.
The sizes and weights of the structures are dictated by the room required by the physics. Welding the support structures to the vessel walls is attractive because the atmosphere outside the vessel is helping to hold things together. If necessary we can do all kinds of things on the outside to stiffen the vessel walls, but it is hard to get an idea of what any of the structure needs to be without knowing how much circulation room the particles need.
The Navy is your customer. The Navy probably wants a better power unit for their submarines. If the result is as big as a house and will only fit into an aircraft carrier, they will probably choke on your design.
If someone adopted my "6 cylinder" approach described previously, a 2 meter diameter magnet would have a roughly 4 meter overall magrid diameter. Add another 2 meters between the magrid and the and the pressure vessel, and you have an 8 meter diameter pressure vessel. 8 meters. 26 feet. big as a small house
But guys,you are forgetting the wonderful scaling law discovered by Dr. Bussard. (B^^3)*R !!
Stop trying to make it bigger, and concentrate on boosting the B field and get cubed improvement instead of boosting R and getting linear improvement. With the current
70cm magnet diameter, the same "6 cylinder" design would have only a roughly 1.5 meter magrid diameter. Add .75 meter to the radius of that for the pressure vessel, and you get a nice 3 meter diameter pressure vessel. Stack radial layers as I suggested before, and you get a long salami 3 meters in diameter that fits nicely in a submarine.
The Navy loves things that are easy to maintain. Make the pressure vessel very stout and give it portholes corresponding to the radial and longitudinal position of each magnet.
Make modular magnet/truss/backplate assemblies as I suggested before. The truss in this case would only be 70cm tall. Nice and short and resistant to bending. Make the backplate so it fits into a modular pressure porthole on the pressure vessel. Make the pressure vessel, (after removing all external power, cooling, whatever, fittings, etc.) Rotate-able on rollers inside the submarine. In dry-dock, a hatch is opened above the engine. The pressure vessel external fittings are removed. The pressure vessel is rotated so that a failing magnet/truss module is exposed on top. Swabbies unbolt the module backplate from the pressure vessel and lift the module straight up and out.
The Navy will love you to death.
If you build a monolythic thing like WB-6/7 where all magnets are wired and cooling-piped and welded together into one big Gordian knot, the Navy is not going to be impressed much.
On the issue of space for electron/ion re-circulation between the magrid and the pressure vessel, a whole lot of space probably is not needed. More important is that the outer negatively charged grid be as symmetrical as possible to the magrid for even flow.