KitemanSA wrote:When I started to reply to this yesterday, I was about to just tell you to read what I had already posted. But then Tom Boydston "tombo" did that really nice graphic that I used in my reply to him a few posts back. So I will use it again by reference here. Now I am going to plead with you to read this with a desire to understand, not a desire to find fault. Please.
Yes, yes I have read all of that. I really am trying to understand what you are on about. So far, though, I haven't been able to picture what you want to do.
KitemanSA wrote:Take the first picture of the two that tombo did above, the one that shows the interconnected piping. Now, in your mind, bow it to a spherical shape. I ask you to imagine that inside those pipes are a system not unlike yours, multi-layers of insulating and heat removing stuff.
Okay, so far, so good. This much I can understand. I keep telling you that it is damnably difficult to do, but you do not seem to want to hear that. Believe me when I tell you that this will result in skyrocketing costs and lengthy delays.
KitemanSA wrote:At the core is a core pretty much just like yours, EXCEPT that it is laid up over a sphere and because all the coils are interconnected it can have a continuous piece of metal within the core that can take a good deal of membrane loads.
I am not at all sure what you mean by "membrane loads". You are not describing a monocoque structure. Let's say we use a good grade of stainless steel cable to try holding the coil together in this configuration. It would be in the center of the winding. The strands of the coil would simply slide past the cable because of the magnetic field, resulting in a rapidly expanding cloud of coruscating spaghetti.
Having beat up on you, I think you might have the germ of a good idea here. A tubular net cradling the core might, I emphasize "might", work. The strands of the net would have to be made from flat strips. Mind you, this would lack the rigidity necessary to keep the coils from flapping around like flag. It would not free us from the need for a surrounding jacket to supply that rigidity AND to circulate coolant/moderator. You have to remember that the core will not be in anyway flexible. Think of it as being made of glass.
KitemanSA wrote:(I also prefer a rounder x-section to MSimon's square one, but I can see some benefits either way). The magnet coils are attached to and supported to that continuous backbone of high strength steel. it is also encased in a pipe of high strength steel.
I have been laboring under the assumption that we cannot use ferromagnetic materials. That is why I...would you please get a Yahoo mail account under an assumed name? Then I could e-mail you some numbers. It isn't that hard to set up and I am not going to hunt you down or blow your cover. Maraging steel might do the job, but I was unable to find out if it is ferromagnetic or not.
KitemanSA wrote:All the magnetic loads resolve to radial outward loads, and they are supported by the equivalent of hoop stresses in that backbone and pipe.
Okay, NOW I can see what you meant by "hoop stress". I'm a petrochem guy. When you say "hoop stress" to me, I think you mean the stresses resulting from pressure in a pipe or a vessel.
KitemanSA wrote:NONE of the magnetic stresses need be reacted outside the core container. The core container need only be supported against gravitational loads by the outside members.
I don't agree with this because my experience with magnets suggests that bad things will happen. Perhaps if we were in freefall things would be different, but this thing will not be built in freefall anytime soon. If the magnetic fields were perfectly aligned and were never perturbed by anything, your idea might hold water. We ain't that lucky. The problem becomes even more troublesome when you start thinking about putting one of these things into a moving vehicle.
KitemanSA wrote:A now very light weight TPS (thermal protection system) can be connected to a similar design of neutron protection system and only supported against gravity loads. Said loads will be quite within the reach of thin section typical metals.
Don't I just wish. I'll need a lot more detail before I buy into this one. The coolants are fluids that have to be pumped through the system fast enough that these light metals will not see too much pressure and rupture. Just as importantly, the coolants will have to pumped through the system fast enough to avoid having the heat reach the SC core. Out of that comes a lot of vibration. Vibration will cause the SC cores to move around which will in turn perturb the magnetic fields, which would, sooner or later, result in cracks in the SC coil and we have our rapidly expanding cloud of coruscating spaghetti.
KitemanSA wrote:1) Staggered buttons of aerogel or the like. 2) Why in the world would you think I want to cool them? The foil will naturally take on the temperature ~1/2 way between the two radient surfaces on either side. In doing so, it cuts energy transmission MARKEDLY. I think it is a 4th power rule.
And after the outermost layer of foil evaporates? The innermost layers will not protect the outermost one.
KitemanSA wrote:I was going to wait to bring this up, but I also think we should rethink the outer water course and use some other material like eutectic NaK or other liguid metal. True we would need some replacement for the H in the water to moderate the neutrons, but... This is still up for discussion as I am not wed to anything on this now.
What is the ratio of potassium to sodium in this solution you are championing? Have you calculated what it will weigh? Have you thought about the vibration that pumping it around in your lightweight structure will cause? You do realize that molten alkali metals are one of the major drawbacks to the ITER design, right? Mineral oil would be a safer and far less troublesome replacement for water, but both of the real-live Nuke-E's we have on this board have both rejected mineral oil as well.
KitemanSA wrote:The magnet does not induce loads on the stainless or the copper or the water or the..., at least not to any significant degree. If your react the MAGNET's magnetic loads out as I have described, the TPS becomes a light add on, probably supported independantly by the outermost course, not touching the inner most course at all. This would actually allow more slop in construction tolerances.
If, IF, we could do what you describe, maybe. What you want to do is to cancel the loads from the magnetic fields by using internal tension members. Bucky Fuller would be proud of you. Convince me that perturbations will not suddenly eat us alive in such a system. I don't think there are any metals that can be used for that kind of load at LHe temperatures. Do you have one in mind? Carbon fiber might do the job, I don't know, but then you will have to show me that there is a combination of supplier/shop that can figure out how to build within a year and at less than astronomical costs.
KitemanSA wrote:I think that the magnet's magnetic loads should be reacted out within the inner-most course and be done with. See above. If you still don't get it, I will take the time to draft up more crude graphics.
If you want me to model it, you gotta send me a sketch and wait while I finish sorting out how to use this program. You would likely get faster results from Tombo because he is obviously a talented draftsman and is already in full command of his software.
At any rate, I would very much like to see a picture of what you have in mind. And, I must add, the finished drawings should be done to scale. We need to be doing more than brochure grade stuff at this point.
KitemanSA wrote:Then please explain why the strongest high temperature fiber known to man is beta SiC? Gee this tensile structure I have described may have to be made with woven fiber, perhaps potted in other ceramic, perhaps just properly wound around the piping providing the LHe. Mayhaps the pipe carrying the LHe would be strong enough to carry the loads and the SiC would just be an insulator.
Okay, you are talking about FIBROUS, not solid SiC. That is a very different beast. I assume you intend to use this material for your structural cables. I won't argue with you about that, but I do suggest that you check to be certain of its behavior at temperatures in the low Kelvins. While you are about it, you need to be thinking about who we would buy this stuff from and who we could contract to fabricate it.
I read about these wizzy-bangy materials all the time, but I damned seldom read of anyone who is actually using them for anything very large if anything at all. You might want to think about tungsten core boron fiber while you are at it. Also, remember that nearly all of these fiber composite materials rely on epoxies to hold them together.
KitemanSA wrote:The thermal protection and neutron conversion/protection system should be made as light and thin as possible and reacted out thru one of the layers of that system.
Again, you are not being clear about what you mean. Could and should I already know about. What I need to know from you is HOW. I am not trying to be an egotistical prig here. Investors and the experts they hire will be demanding to know the same things.