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Re: [TCML] Aluminum Plate Faraday Suit

On 1/19/20 6:22 PM, William Noble wrote:
Before you get yourself killed, do a little research on EMI/EMC suppression, "faying" surfaces, and EMI gasketing.  The power levels in a tesla coil are "modest", what you need is well understood, but you are not going to get there the way you are going.  Please take care.  There are very specific steps people designing high power transmitters take, there are tools for analyzing EMI and cosite interference, electromagnetic interactions and so on, you can probably work with a local university for some help.

These links can get y ou started

Useful stuff, however, this is not a typical "EMI shielding thing" - the frequencies are very low - 100s of kHz. the gaps in any practical suit are so small compared to a wavelength that they aren't there. You're not shielding against a "radiated field", you're in the near field.

This is more about providing a path for current to flow when a streamer touches you.

The usual problem that arises with aluminum, as you've noticed, is that it forms a thin oxide layer, so making reliable electrical connections with ring mail is going to be tricky.

So what you're thinking is that if you bond all the plates of your plate armor together, it will provide a path.

The way we solve the "oxide" problem in electronics assemblies is by chemical conversion coating of the aluminum to give it a conductive surface. Kind of like anodizing, except it's conductive. Alodine and Iridite are trade names of such coating. Historically, it would be a chromium compound, but because of the issues with hexavalent chromium, other things are used today.

The coatings can be done to yield a colorless finish, although colored finishes are more common (because it's easy to tell if the part was properly processed or if there are voids).

As far as making connections - is your suit of armor such that some pieces are always attached to others (with a flexible connection)? so if you had a "permanent" bonding wire that would work? You might look at getting someone to braze or TIG weld the wires. The trick might be finding a suitable flexible aluminum conductor that won't work harden and eventually break. You can get thin aluminum ribbon, but, I'd worry about the work hardening - maybe someone on the list can suggest a suitable alloy, or wire. They *do* make stranded aluminum wire.

They also do make coaxial cables designed for repeated flexing with aluminum shields, so someone has figured this out.

If you're going to mechanically attach dissimilar metals, you'll need to worry about electrochemical effects (corrosion) - the usual strategy is to clean the surfaces really well and use a product like NoAlOx in the gap, and clamp/join it well enough to form a "gas-tight" seal.

You might be able to do something along those lines with rivets

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