This is similar to my previous post but now I have researched EMPs a bit more and can offer the following advice to those wishing to store equipment
and harden it against all type of EMP:
- Insulate and space all layers with a good insulator.
- Paint each metallic layer with several coats of varnish, inside and out.
- Have 2 or more inner layers constructed of a high Mu metal with close fitting lids.
- Have a single lead layer for the innermost layer to absorb as much gamma radiation as possible
- Have an outer faraday cage constructed from a good conductor with no holes or gaps. The lid seal should incorporate a continuous conductive
gasket.
- Ground the Faraday cage with multiple, flat conductors to the best grounds possible. Do not use the mains supply earth on its own. Metal water
pipes and buried earth rods should do the trick.
This gives the following construction:
1. Faraday Cage
2. Insulator
3. High Mu Box
4. Insulator
5. High Mu Box
6. Insulator
7. Lead
8. Insulator
9. Electronic Equipment
Don't both with mutliple Faraday cages or wrapping the devices in foil etc. If your main concern is nuclear EMP then I suspect you could make do
with a single High Mu enclosure.
With this construction your devices should survive all the different type of EMP you may encounter.
The problems with EMP come from:
1. High intensity gamma burst which can damage semiconductor junctions via ionisation.
2. High intensity, high frequency electrical field. This will induce high voltages in any conductor.
3. High intensity, high frequency magnetic field. This will induce current in any conductor.
4. Long duration geomagnetic field. This will induce current in conductors, the longer the condutor the worse it will be.
And before someone asks, yes I am qualified in this area. Protecting devices that is, rather than EMP