EMP protection for external computing HDDs

[Erina]

With the war on the continent hotting up I would like to know how to protect my computing equipment against an EMP attack.

I would like to avoid the whole "you'd have more things to worry about" line, and just stick to the science please.

Specifically, how do I test a system ? I was thinking about placing a cheap HDD in an EMP protective environment and then inside a microwave, as I do not have the necessary devices to test for signals.

I read about bags, but unless ironed the zip lock seal is a weak point. It seems that metallic cloth gives favourable results, and it's very much more flexible and robust, compared to a polymer bag.

Any advice please.

[MigL]

Modern 'flash' memory would probably be more easily corrupted.
An EMP pulse will force electrons from the conduction and semi-conduction bands, and since SSDs store electrons in a silicon gate after being deposited there by a MOSFET, they will easily lose the charge that indicates '1' or '0'.
Old style rotating platter drives, that store data in magnetic domains, especially low-density ones with larger magnetic domains, may be mor resistant.

[Erina]

You're probably right.

However, with a metallic cover, I am hoping to keep the HDD/SSD safe.

[studiot]

If the armour plating on a tank or a battleship is insufficient shielding against an EMP weapon, I doubt you could shield you computer.

It has been suggested that old fashioned valve technology is more resistant than modern semiconductors on account of the very much higher breakdown voltages/field strengths involved.

[Moontanman]

Put your computer in a metal trash can and ground the can to the earth. 

3 hours ago, studiot said:

If the armour plating on a tank or a battleship is insufficient shielding against an EMP weapon, I doubt you could shield you computer.

It has been suggested that old fashioned valve technology is more resistant than modern semiconductors on account of the very much higher breakdown voltages/field strengths involved.

Actually modern military equipment is hardened against EMP. 

 

[TheVat]

15 hours ago, Erina said:

With the war on the continent hotting up I would like to know how to protect my computing equipment against an EMP attack.

I would like to avoid the whole "you'd have more things to worry about" line, and just stick to the science please.

Specifically, how do I test a system ? I was thinking about placing a cheap HDD in an EMP protective environment and then inside a microwave, as I do not have the necessary devices to test for signals.

I read about bags, but unless ironed the zip lock seal is a weak point. It seems that metallic cloth gives favourable results, and it's very much more flexible and robust, compared to a polymer bag.

Any advice please.

Once you've got a good Faraday Cage, drop your cellphone in there, and try to call it from another phone.  A pretty reliable test.  (My spouse has some valuable data stored at home, so we made several FCs in case of EMP attack)

Avoid things that have power cords going into them, even if they appear to be a tight metal box.  Moon's trash can is a good one. Be sure it's lined with something so that your computer hardware isn't touching the walls (i.e. air gap).  Antique dealers sometimes have old double boilers, or any large metal cooking vessel with a tight lid.  Small items, like thumb drives, can go in old metal food tins if tightly lidded.  

May you never have need for this.

[Erina]

My understanding is that a Faraday cage need not be grounded ?

[John Cuthber]

Am I the only one who regrets the passing of metal biscuit tins and their replacement by plastic ones?

[TheVat]

19 hours ago, Erina said:

My understanding is that a Faraday cage need not be grounded ?

Yes, but grounding makes certain no charge lingers in the containment vessel.  With a very strong EMP, this insures you won't get a shock touching it.  Grounding can be as simple as just letting it touch the ground or a cellar floor.

4 hours ago, John Cuthber said:

Am I the only one who regrets the passing of metal biscuit tins and their replacement by plastic ones?

No, you are not.  😀

[Moontanman]

4 hours ago, John Cuthber said:

Am I the only one who regrets the passing of metal biscuit tins and their replacement by plastic ones?

I regret the change to plastic packaging! Glass bottles and metal tins were the best! 

 

[Erina]

I found this demonstration, which doesn't seem to have an air-gap:

 

Can I really just place a HDD inside a metal pot, with some tin foil, and that will protect it from an EMP ?

 

[exchemist]

On 10/23/2022 at 1:43 PM, John Cuthber said:

Am I the only one who regrets the passing of metal biscuit tins and their replacement by plastic ones?

Ah, so the meringues I make are hardened against an EMP, then. Good to know.

[Erina]

As a Faraday cage does not need an air-gap, and is basically a metal box, what about two oven trays placed edge to edge, with electrical tape used to seal them together, surely that would be sufficient ?

https://www.amazon.co.uk/Baking-Cookie-Stainless-Healthy-Dishwasher/dp/B09L6R1LRZ/ref=sr_1_50?crid=1TF3AHE9L064K&keywords=oven%2Btray&qid=1666812048&qu=eyJxc2MiOiI2Ljc3IiwicXNhIjoiNi4wMCIsInFzcCI6IjUuNzAifQ%3D%3D&sprefix=oven%2Btray%2Caps%2C262&sr=8-50&th=1

 

[swansont]

11 minutes ago, Erina said:

As a Faraday cage does not need an air-gap, and is basically a metal box, what about two oven trays placed edge to edge, with electrical tape used to seal them together, surely that would be sufficient ?

https://www.amazon.co.uk/Baking-Cookie-Stainless-Healthy-Dishwasher/dp/B09L6R1LRZ/ref=sr_1_50?crid=1TF3AHE9L064K&keywords=oven%2Btray&qid=1666812048&qu=eyJxc2MiOiI2Ljc3IiwicXNhIjoiNi4wMCIsInFzcCI6IjUuNzAifQ%3D%3D&sprefix=oven%2Btray%2Caps%2C262&sr=8-50&th=1

 

EM waves can leak through small gaps. True EM protection requires a certain length for it to act as a waveguide below cutoff.

[Erina]

I am unsure what you mean ?

You mean the length of the wave e.g. low frequency ? Surely, higher frequency waves would be more of an issue ?

With electrical tape around the two openings, that would be a secure seal ?

[swansont]

9 minutes ago, Erina said:

I am unsure what you mean ?

You mean the length of the wave e.g. low frequency ? Surely, higher frequency waves would be more of an issue ?

With electrical tape around the two openings, that would be a secure seal ?

Electrical tape isn’t conductive, it’s an insulator. It doesn’t do much to attenuate the wave.

To attenuate an EM wave through a gap, the conductor needs to have a minimum length. You can think of a wave that hits the gap when the wave amplitude is at its minimum; the conductor has a minimal effect, so the wave can still get through it.

This is why penetrations of a Faraday cage/EMP enclosure have diameter and length specifications 

[Erina]

What about a metal paint pot ?

Surely that would work ?

I meant metal tape, sorry.

[MigL]

Depending on the distance to the nuclear detonation that produces the EMP, conduction and 'free' electrons are easily driven out of wiring/conductors, batteries/capacitors, integrated circuits, etc.
Why would anyone think a Faraday cage of lesser thickness would suffice ?

And if a Faraday cage is composed of pieces that are not electrically connected to each other ( like two cookie sheets ), the pieces act as antenna/re-radiators, not a shield.
Keep your baking sheets and biscuit tins for cookies.

[Erina]

Do you mean dB levels of resistance ?

I understand that a Russian doll approach of "layering" can multiply the level of dB protection.

You can see from my drawing above the idea of two identical oven trays, of which are completely sealed on five sides, can be tapped together with aluminium/copper tape at either open end, right around their perimeter.

Surely, this would shield the internal items to at least 40-50dB ?