EMP

[Luke Starkiller]

I was just wondering what makes EMP so damaging. Is it the frequency or the intensity or some combination? Is there any practical way of generating a short range, directed pulse short of nuclear detonations?

[Darth Wong]

I was just wondering what makes EMP so damaging. Is it the frequency or the intensity or some combination? Is there any practical way of generating a short range, directed pulse short of nuclear detonations?

I believe it has to do with charged particles being hurled away in large quantities at very high velocities, thus creating powerful magnetic fields that induce current to flow in electronics, thus blowing out circuits. I know they're working on smaller-scale EMP weapons, but I don't know what kind of progress they're making.

[Sokar]

Disclaimer - Im not a science major, but I have an active intrest in these things. If Im wrong about this , please feel free to correct me, Im doing this off the top of my head:-)

EMP is so damaging due to the effect it has in electrical equipment, it essentialy nullifies the properties of conductivity and makes electric motors , power-lines, printed circuits ect into inert lumps of metal and silicon. If an EMP pulse were to hit you , everything electrical would instantly go dead, and never work again. EMP'ed equipment has to be replaced there is no decon that I know of that will restore it. EMP's area of effect is proportional to its power, you can generate focused EMP effects with the right equipment, such as some of the proposed concepts for stopping cas in a pursuit by frying its brain box with a low power EMP pulse device. A nuke that is detonated outside the atmosphere can potentialy effect the entire country and a staggered detonation of 6 or more would knock us right back to the Stone Age.

[Crayz9000]

A nuke detonated outside the atmosphere would have to be in the high megaton range if you wanted it to seriously affect anything on the ground; otherwise, the atmosphere would absorb a lot of it.

A nuke in space would, however, be wonderfully effective at disabling all sorts of satellites, and even other undeployed nukes.

IIRC, the first documented case of the EMP effect was during testing at Bikini Atoll in the South Pacific. One above-ground test actually blew out streetlights in Hawaii, but didn't do much else in the way of damage.

[Darth Wong]

Actually, a low-orbit megaton-class nuke would cause massive ionization of the upper-atmosphere, thus causing a widespread EMP effect. Assuming you take the word of Sublette's oft-cited Nuclear Weapons FAQ.

[GrandMasterTerwynn]

Disclaimer - Im not a science major, but I have an active intrest in these things. If Im wrong about this , please feel free to correct me, Im doing this off the top of my head:-)

EMP is so damaging due to the effect it has in electrical equipment, it essentialy nullifies the properties of conductivity and makes electric motors , power-lines, printed circuits ect into inert lumps of metal and silicon. If an EMP pulse were to hit you , everything electrical would instantly go dead, and never work again. EMP'ed equipment has to be replaced there is no decon that I know of that will restore it. EMP's area of effect is proportional to its power, you can generate focused EMP effects with the right equipment, such as some of the proposed concepts for stopping cas in a pursuit by frying its brain box with a low power EMP pulse device. A nuke that is detonated outside the atmosphere can potentialy effect the entire country and a staggered detonation of 6 or more would knock us right back to the Stone Age.

Actually, Wong had it right. The sudden influx of charged particles induces an electrical current in all conductors nearby. The magnitude of this current is enough to pop the junctions of transistors (such as those that drive digital equipment.) As a result, transistorized equipment, unless properly shielded or hardened, tends to go very dead very quickly. (Though vacuum tubes could handle greater current spikes, making them resistant to EMP.)

And it is actually fairly easy to build small-scale EMP weapons. What you need is a big battery, a metal coil, some wiring, and an explosive. Put the coil around the explosive. Wire it up to the battery and some timing circuits. Right before you set off the explosive, energize the metal coil. Then when the explosive goes off, it will disintegrate, compressing the EM field generated by the coil. This produces a EM pulse that'll do nasty things to say, a small city.

[Perinquus]

Hah, bring on the EMP! All my other electronic devices may be reduced to inert objets d'art, but at least my 1937 Zenith radio will still work! (Vacuum tubes you see - much more resistant to EMP than solid state electronics.) Of course, I probably won't be getting any electrical power, but who cares about little inconveniences like that?

By the way, here's a nice (if rather long) tactical anaysis of the potential effects of EMP on the modern battlefield, written by a U.S. Marine Corps officer:

http://www.globalsecurity.org/wmd/libra ... 84/ERD.htm

It was written back in 1984, so it still focuses on Soviets as the likely enemy.

[UltraViolence83]

I actually want the world to enter into an EMP scare; it'll teach us not to rely so much on electronics, which many people seem to claim as our savior. That's why I'm against the (somewhat unlikely) idea of a totally paperless society. EMPs would wreak havoc and we'd be fucked like JFK on Marilyn Monroe. If all our important documents are on paper first, and then copied to computer for backup, you won't have to worry about it so much.

Oh, didn't that one sci-fi military writing tips page on SD.Net's links page talk about HERF guns, which cops use to short out cars? Those're pretty small-scale, I guess. That's why I want my car to be high-tech free, that way EMP weapons can go fuck themselves.

Off-Topic: This thread justifies the use of vacuum tubes in the sci-fi world I've written up. Seems like my ideas are being shown to be more and more feasible all the time.

[UltraViolence83]

Perinquus: do you collect old eletronics? I kinda do. I really like the old 80's TVs that are huge and built into oak. I've also got a thing for fake wood. I have an old top-loading VCR that I use as a nightstand in my room, and an old tiny little TV I use as a footstool.

[Tom_Aurum]

Okay, how precisely <do> you shield something against emp? Vacuum encasing the motherboard? Lead shielding?

[Perinquus]

Perinquus: do you collect old eletronics? I kinda do. I really like the old 80's TVs that are huge and built into oak. I've also got a thing for fake wood. I have an old top-loading VCR that I use as a nightstand in my room, and an old tiny little TV I use as a footstool.

I've got a Western Electric 202 telephone from the late 20s or early 30s:



a 1938 Zenith 12-S-265 (listed 1937 earlier in error):



and a General Electric fan from 1909:



They all work. (The pictures aren't of my actual items, just similar ones whose pictures are available at various sites, BTW - in fact my GE fan looks much better.) If you walk into my living room, it looks rather like something from about the mid 1930s, which is intended. I just like the look of that era, mission furniture, art deco and all that.

[UltraViolence83]

I envy you.


Do you have one of those TVs that have circular screens and generate everything so that it looks blue?

[UltraViolence83]

I also dislike how DVDs are going to wipe out VHS.

VHS advangtages: MUCH more durable, unscratchable (unless you purposely damage the tape) and uh...well, that's it. But I've the horror of renting DVDs that skip. At least VHS tapes just go past the impurity.

[Perinquus]

Fraid not. Vintage TVs come a little later than the stuff from the era I'm collecting items from. Though I wouldn't mind picking up an old Philco Predicta



if I could find one in working order. That's not easy to do though, since they were not very reliable, which is why they only made them a few years.

There's a company called Telstar which is making a modern, color version, with updated electronics that should solve the reliability problem. They look exactly like the originals, but I've never been able to work up much enthusiam for reproductions. I want the real thing.

[Perinquus]

I also dislike how DVDs are going to wipe out VHS.

VHS advangtages: MUCH more durable, unscratchable (unless you purposely damage the tape) and uh...well, that's it. But I've the horror of renting DVDs that skip. At least VHS tapes just go past the impurity.

Tapes only last about 15-20 years or so, and then the iron oxide particles on the tape start to lose their magnetism. Might as well throw the tape away at that point. DVDs will last much longer.

[UltraViolence83]

Could just record and make a copy of it before that happens, then do it again a decade later. When I'll have to use DVDs for everything, I'm going to make recordings of new ones I just get. That way I won't have to worry about the original fucking up.

[Perinquus]

Could just record and make a copy of it before that happens, then do it again a decade later. When I'll have to use DVDs for everything, I'm going to make recordings of new ones I just get. That way I won't have to worry about the original fucking up.

Problem is, you're making a copy of a copy of a copy, and so on. You get markedly deteriorating picture quality each time. The fact that you'd be making a recording of an old, deteriorating copy won't help either.

Face it, VHS will soon join betamax, 8 tracks, and vinyl LPs as obsolete technology. The only thing that's really keeping it around at this point is the fact that you can record over a videotape multiple times, while a DVD can only be recorded on once.

[Dark Hellion]

About EMP shielding, they can do it, but I think the method is classified. I know that almost all U.S. military equipment has hardened electronics.
And the U.S. has small scale EMP devices that can be stuck in the nose of a tomahawk missle. We will probably use them on Iraq whenever we get around to whomping their asses. (Yes I am an ignorant american )

[kojikun]

the us military is working on building microwave pulse cruise missiles. anyone thats worked with microwaves knows that the signals are a bitch and can knock out electronic circuits with ease.

ofcourse, shielding against it is relatively easy, just build a faraday cage around yourself or wrap whatever in aluminium foil. works great, but doing so prevents you from sending radio transmissions or using radar so anything that works on RF or microwave signals is screwed.

this is what hellion refers to when he speaks of a small scale emp device.

as for EMP proper, i cant say how easilly shielded it is. if its actual radio/microwave signals that fuck the shit up then the shielding would be the same, but if its a magnetic pulse and electrostatic charge wavefront moving through the atmosphere (which is apparently the effect since it requires something to ionize) then I suspect the best way to shield against it would be the same way you shield monitors and tvs against powerful magnets in speakers.

[Zoink]

Was the device in the movie "Ocean's Eleven" realistic? Did it really need that glowing bubble tank (I think the coils were in there)?

[kojikun]

ive not seen the movie but i can say it aint.

[Crayz9000]

Aluminum foil is going to do exactly jack shit against an EMP device. You might as well make a hat out of it.

Only a Faraday cage will work, and even that depends on the proximity to the EMP device.

[Tom_Aurum]

And, on the risk of being flamed: What's a faraday cage?

[GrandMasterTerwynn]

And, on the risk of being flamed: What's a faraday cage?

A big metal box surrounding whatever you want shielded. This metal box has to be very well grounded. The concept behind the Faraday cage is simple. Electrical charge likes to flow along the outside of a conductor. So, if you put your sensitive equipment inside a Faraday cage and ground it very well, then the charge will flow along the outside of it, and down to the earth. Mind you, you'd want to turn your computer off and unplug it if you knew the EMP pulse was coming beforehand, otherwise you'd get a nice electronics-ruining surge up your power cord.

[GrandMasterTerwynn]

Okay, how precisely <do> you shield something against emp? Vacuum encasing the motherboard? Lead shielding?

As has been stressed before, a faraday cage. The military has hardened computer circuitry (hardened as in it can withstand much nastier current spikes than ordinary consumer electronics,) which will protect from mild EMP effects. Mind you, that's partially why military computer equipment in the field lags so far behind the cutting edge of consumer technology. It's much easier to harden something like an 80386 (fewer transistors and humongous feature sizes) then it is to harden an Athlon XP (many transistors with feature sizes of about .18 to .13 microns.)