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 ```I need to build an electromagnet which at the ends will have a field strength of 1.5 Tesla (1 Tesla would be suffiecient at minimum). The electromagnet will be used for repulsion. I have used an iron core and I am able to construct an electromagnet of 0.15 Tesla but that is not strong enough. Refer to the following page: http://www.oz.net/~coilgun/theory/materials.htm I also have a electromagnet with a air-core which reads about 35 Gauss. If I were to put supermalloy in the air-core then will the electromagnet be 35 Gauss * 100 000 = 3 500 000 Gauss ? I know something above is wrong. Can you please tell me what is wrong with the mathematics above? So, what metal on the list is best to replace the air-core? Also, where can I get that metal? Thanks in advance.```
 ```It is not very complex: ... the permeability is actually the slope of the BH curve. The steeper the curve, the higher the permeability as shown below... http://www.coilws.com/magneticandhow.html But a bit more complex then just multiplying H by permeability to get B: That BH curve is not a straight line, it reaches saturation, which depends on the material: ..The typical saturation flux density of Power Ferrite material is under 4000 gauss (400mT). Whereas the saturation flux density of MPP material is 7000 gauss. High Flux is 15,000 gauss and Iron Powder is 10,000 gauss... http://www.coilws.com/magneticandhow.html Cobalt based alloys have been developed which have high saturation : The important series of alloys from cobalt?s point of view are the Co/Fe series typified by Permendur ? this alloy being modified by vanadium additions to improve ductility. The reason for the use of cobalt is that this alloy benefits from the maximum saturation known, 23,500 gauss (2.35 Tesla) with a square shaped hysteresis loop, and also from the high Curie Point. http://www.thecdi.com/cobalt/magneticalloys.html It all depends on Temperature too, of course - and required frequency response - and size and uniformity of field in a cavity... do a search on SEARCH TERM: curie point, saturation, hysteresis, slew rate You may want to learn from the people who build MRI machines and particle accelerators. MRI equipment ranges from 0.2 to 9.0 Tesla, accelerators use superconducting coils .. Here is an example of 'state of the art' MRI: "..High Power MRI Machine Coming to the Center for Biomedical Imaging at NYU ... a team of scientists who designed and installed the world's first 3-Tesla MRI ..." http://www.med.nyu.edu/communications/news/pr_27.html You did not describe the scope of the effort and resources. It gets expensive as you reach for higher flux density and size of the cavity. Here is a technical paper on design of MRI coils which reach 3T http://www.dotynmr.com/PDF/2002_Doty_NIH_HGrad.pdf Here is an example of 'your tax money at work' in a national lab: They call 2.3 T a low field magnet (built with and limited by saturation of the iron core) and mention rare earth materials and 'commercially available HTS' for design of High Density magnets. http://www.bnl.gov/magnets/Staff/Gupta/Publications/pac97/3p004.pdf It is a actually a field of study to which whole monographs and courses are dedicated: e.g.: http://www.nap.edu/books/0309095824/html/ good luck Hedgie``` Clarification of Answer by hedgie-ga on 13 Jul 2005 08:24 PDT ```If there are questions remaining, please, post a RFC (Request for Clarification). If all is clear, rating is appreciated. Hedgie```