If holes are being cut in the steel for cores, can you pass light between the two boxes? Like a bright globe or LED and a solar panel on the other side, this will give you a few watts out of 100.
I once made a battery charger that would charge across an airgap of around 3cm using resonant LC on each end. Not particularly high power, but not wildly inefficient either.
-- Dirk http://www.onetribe.me.uk - The UK\'s only occult talk show Presented by Dirk Bruere and Marc Power on ResonanceFM 104.4 http://www.resonancefm.com
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