jimk@iscuva.ISCS.COM (Jim Kendall) (07/16/87)
Keywords: First of all, please excuse my ignorance. Could some kind sole out there explain to me: a. The the properties of the magnetic field in a superconductor. b. The effects of external magnetic fields on a superconductor. c. How to construct a motor using superconductors. It is my understanding that external magnetic fields do not affect a superconductor which leads me to wonder how a motor would work. Again, it's probably something simple, but it escapes me. Thanx in advance ----------------------------------------------------------------------- I refuse to write a disclaimer.... ----------------------------------------------------------------------- Jim Kendall ISC Systems Corp. E.22425 Appleway Liberty Lake, WA 99019 509-927-5751
beckenba@cit-vax.Caltech.Edu (Joe Beckenbach) (11/04/87)
* ----- The latest issue of OMNI magazine (November 1987, page 72+) has an article on how to make your very own batch of Y1Ba2Cu3Ox liquid-nitrogen superconductor. To make "123", as it's called, combine 1 part yttrium oxide, 2 parts barium carbonate, and 3 parts copper oxide. Grind to powder, bake at 900-950C for 12 hours. Cool in kiln, regrind, and compress the powder at 15000-18000 pounds in a hydraulic press. Rebake in oxygenated kiln, let cool very slowly (minimum 8 hours). You now have a fragile superconductor which crumbles on absorbing moisture. As author Bruce Schecter points out: "Please remember, recipes are rarely complete. The experienced chef knows this and fills in missing steps unconsciously. The same is true of laboratory recipes. The consequences of mistakes in the kitchen are only unpalatable; laboratory mistakes can be dangerous, or even deadly. So have a professional, such as a [good] science teacher, in the room while work is being done." Three other notes: 1) This was reproduced without permission, and so I had to leave out some of the details of acquisition of materials and machines. I suggest that anyone interested in this sort of project buy up an issue of OMNI with this article, order a reprint, or in some like manner acknowledge Mr. Schecter'sgood work. 2) Caltech has the capacity to do this project, perhaps in conjunction with the Secondary Students Project. As Mr. Schecter notes, this is one of the best ways to incite the next generation to learn about science: hands-on participation. 3) A resounding "Amen" to the laboratory dangers warning: in my frosh lab we made chips with 'large' transistors. The photoresist only smelled bad; the hydrogen fluoride etch was the real nightmare-producer: the only thing worse than one HF spill on a person would be one HF spill which was neither washed thoroughly nor neutralized by calcium compound injections. On a similar note, an acquaintance in high school built a working model of a volcano using gunpowder. He tried looking into it to see if the cycle was starting. Luckily my sister kept her head when the thing spread itself over the room: he kept his eyes thanks to that. -- -Joe Beckenbach (CS BS '88) Note: Space colonies go outside the magnetosphere. It's war in the Persian Gulf. I can't get a date for Saturday night. Oh, the horror! :-)
fiddler%concertina@Sun.COM (Steve Hix) (11/04/87)
In article <4405@cit-vax.Caltech.Edu>, beckenba@cit-vax.Caltech.Edu (Joe Beckenbach) writes: > > The latest issue of OMNI magazine (November 1987, page 72+) has an > article on how to make your very own batch of Y1Ba2Cu3Ox liquid-nitrogen > superconductor. To make "123", as it's called, combine 1 part yttrium oxide, [ Outline description deleted ] > 2) Caltech has the capacity to do this project, perhaps in conjunction > with the Secondary Students Project. As Mr. Schecter notes, this is one of the > best ways to incite the next generation to learn about science: hands-on > participation. A local (Gilroy, CA) high school science class had an interesting project recently. They produced some "123" and checked it by way of magnetic repulsion (Meissner Effect?). They succeeded twice. Besides the science teacher supervising, they had some counsel from a researcher from IBM who lived in the area. Now *that* sounds like a fun class! seh