What metal would be able to block an EMP?

If I were designing a base for my evil minions and wanted to have my gizmos (electronic not gremlinous) protected from EMP what would be the best metal to use for my base’s shell?

actually what material metallic or otherwise.

A big old Faraday cage would help you out. I’d go with a gold plated geodesic dome over the whole structure. If you prefer a more sinister look, titanium or blackened iron (any conductor) would also work. You’ll have to be careful with any cabling going into the base, or it’ll act as an antenna and channel the destructive EMP straight to your electronics.

Would nesting Faraday cages increase the protection?

Maybe, but a single one is already going to be extrordinarily effective. If a space is surrounded by a good conductor, it isn’t that only 25%, or 5%, or 1% of the electric potenial fields make it back into the Farraday cage, none of it does; and you’d be better off purchasing super-intelligent chimp security officers to torture secret agents anyway.

Actually the security guards range from cyborgs to genetic experiments- www.gene-x.co.uk

Well, of course one is going to get the super-intelligent chimp security officers anyway… it kinda goes without saying.

In the is case the choice of material is important, even critical. In an EMP you’ve got both transverse electric and magnetic fields. Unless your cage has has a high mu (permeability), the magnetic component will be unaffected. It’s the magnetic pulse that does most of the damage, anyway, by inducing high voltages in the conductors of electrical and electronic devices, causing burned out circuit paths and damage to solid state components. Ordinary steel will work fairly well, but for the best protection, you’ll want something like mu-metal, a nickel-iron alloy. Plus it’s cheaper than gold or titanium, which is great for evil overlords on a budget. :wink:

And if you’ve got the budget and the cryogenic equipment, any superconductor will work superbly well at blocking both electric and magnetic fields. The downside is that there is not yet any known room-temperature superconductor, and if your cryogenics fail, most superconductors become pretty good insulators (which will do nothing to shield you). You might want to nest a metallic layer inside the superconductor, not to decrease the penetration (the superconductor by itself is adequate for that), but to provide redundancy in case of cryogenic failure.

And silver actually has a slightly higher conductivity than gold, with copper not far behind, for a much lower price. On the other hand, gold, being dense, is also a pretty good shield against radiation, so you’d get double duty from it.

  • I did eventually find one way to tell some difference myself: if you sandwich a magnet between a piece of mu-metal and a piece of regular steel and hold the metal edges to a TV screen, you can see the different concentrations of the flux lines in the two materials by how much they deflect the image on the screen.

  • Crutchfield sells smaller pieces of thinner foil for about $20 if you want to experience the boredom for yourself, but that’s about twice the going rate–if you can afford or use at least 10-12 feet of it at 16-18 inches wide. It is usually sold in very thin sheets or foil because if it is heated to its melting point or bent too much, the molecular structure is disturbed and the magnetic conductivity drops way off. Thin sheets and foil can easily be bent around objects without ruining the important properties of the material. It also is typically “rolled”, and has a longitudinal grain that should be oriented between the poles as well. …About the only consumer application of it is that occasionally it is sometimes used as foil to wrap speaker magnets, to prevent their fields from causing distortion in nearby CRT screens… -which is why Crutchfield and other upper-end audio outfits sell it.

  • The reason I decided to dump such a load of money on it in the first place was that I read a technical account somewhere that noted that when all factors are taken into account, making magnetic shielding out of mu-metal is certainly faster and easier, and usually cheaper than using performance-comparable amounts of ordinary steel or iron. In some space-restricted instances, one thin layer of mu-metal foil can provide more shielding than filling in the entire available space with steel.