EMP question.

Just curious really. It seems in the upcoming Tom Cruise movie (War of the Worlds) the martians use some type of EMP weapon to disable human machines. Don't militaries like U.S. have sheilded systems to prevent EMP failure? (like in a nuclear war type situation) Also, are the electronics permenantly fried afterwards? Any ideas?

If the power is turned off then the EMP does no damage, the security system may be a detection of a blast or pulse that triggers a system shut-down. If they are on during it then yep they will be burned out.

I think the EMP works also, if the systems are shut dow. However it is posible to shield the important devices. Only some things like planes are difficult to shield. In fact emp pulse is better to use against civilian infrastructure to crate chaos.

Power on or off doesnt matter. If there are cables attached or any conductive surface large enough to act as an antenna (around 32inches), the radiation will be absorbed and follow any available path to ground through the components.
This depends on the type of EMP.
If it is uwave radiation, the above applies. The effects are the same as metal in a microwave oven: there is a buildup of micro(u)wave radiation in the materials until discharge. In electrical components, anything solid state is permanently fused. This is the type of EMP generated by a nuclear detonation. Most shielding consists of a "cage" surrounding the sensitive systems to absorb the radiation and drain it to ground. Everything within the shielding must be completely independant, isolated from, and have no direct connections through the shield. If a cage type system is not used, then transorb diodes are usually placed at all entry points into the circuitry, allowing any significant overload to drain safely to ground.

If the EMP is an intense focused magnetic field, the collapse of the field will induce a massive buildup of energy in any device within the field. Same as above, the energy will discharge destroying many components, but it is possible for some tougher components to survive and simply be stuck open until the energy dissipates. EMP's like this can affect anything from wrist watches to airliners, and shielding has little effect.

I heard lead protects from EMP

With a strong enough EMP even if electronics are turned off they can be damaged.

Machines can also be shielded against EMPs most of the nuclear infrastrure in the US is shielded places like NORAD etc... Electronics can be shielded in many ways everything from just the way you design them ie surge protectors stuff like that, to a physical shield like steel,lead and even concrete. Really any dense material can work.

Depending on the power of the EMP and type of shielding you could need as little as a few millimeters shielding to as much as a few meters.

[edit on 20-2-2005 by ShadowXIX]

you know directed emp could actually if controled be used to power electronics in the feild that require large enough quantites of energy that batteries are impractical.this is my theory based on my knowledge of what emp is and what it does. see emp destroys electronics by flooding the pathways with electrical energy to the point of burnout by my understanding if a pulse wave were emmited and your shielding was attached to a capasitor to regulate power flow you could in turn use that energy to power your device. now if you have this and the enemy doesn't then in providing yourself power your also crippling the enemys electronic capibilities. the problem however is sending pulses in regular intervals. see aside from a major fussion or fission reaction the only way that i know of to generate emp is by overloading a curcuit to the point of bursting in turn releasing the energy (meathod aquired form book 28 devices for the evil genuis).

Here is a link to some official gov stuff on this. May not be exactly what you want, but its very interesting.

www.thememoryhole.org...

kains: what you are basically describing are microwave systems. You can send "power" over great distances with microwaves. Typically just a transmit dish and a collector in line of sight. Review my previous post in this thread, the type of emp you are familiar with is microwave radiation discharge. A small device can easily be built with a microwave oven magnetron, a high voltage source or cap, and a spark gap or two. (Note I highly recommend you do attempt construction of such a device. Microwave radiation can kill you, cause severe internal burns, and even cancer. Plus we're talking about 2000-30000VAC.)

> skippy: awesome, can't wait to get my phaser permit

[edit on 24-2-2005 by apc]

In order to understand your question, and make a contribution to this discussion, I feel that I must ask you a question or two.

Does your original question refer to the Electro Magnetic Phenomena produced within the first sixty seconds of a nuclear explosion or, are you refering to the Electro Magnetic Pulse which is a 'by product' of EMP?

I heard that the U.S was going to deploy some EMP weapons in Iraq,does any one knnow if anything came of this?

Originally posted by maninblack
I heard that the U.S was going to deploy some EMP weapons in Iraq,does any one knnow if anything came of this?

Doubt it, unless they want apaches falling from the sky!

Originally posted by devilwasp

Originally posted by maninblack
I heard that the U.S was going to deploy some EMP weapons in Iraq,does any one knnow if anything came of this?

Doubt it, unless they want apaches falling from the sky!

I cant find the data, but I could have sworn I read that there are 4 humvee's armed with EMP devices in Iraq.

Originally posted by skippytjc
I cant find the data, but I could have sworn I read that there are 4 humvee's armed with EMP devices in Iraq.

Yeah I heard that to, one fatal flaw though....how do they start the humvee's again?

Originally posted by devilwasp

Originally posted by skippytjc
I cant find the data, but I could have sworn I read that there are 4 humvee's armed with EMP devices in Iraq.

Yeah I heard that to, one fatal flaw though....how do they start the humvee's again?

Maybe they are shielded? Or maybe the way the weapon is designed it doesn't effect the platform its fired from since its being directed away from the humvee? If the EMP energy is going away from you I don't see how it would effect the equipment on the backside of the weapon?

Maybe they are special modified humvee's with no real electrical system, ECU etc... Once a diesel is running you really dont need one.

Originally posted by warpboost
Maybe they are shielded?

.....I thought about it but in my opinion not really woth it, if its on the back of a humvee the electromagnet shielding or faraday cage will be useless since all it would do was contain the pulse.

Or maybe the way the weapon is designed it doesn't effect the platform its fired from since its being directed away from the humvee?

EMP doesnt wrk like that, atleast I think no.

If the EMP energy is going away from you I don't see how it would effect the equipment on the backside of the weapon?

It goes away in all directions, so therefore would go through the humvee.

Maybe they are special modified humvee's with no real electrical system, ECU etc... Once a diesel is running you really dont need one.

Yeah a diesel would work, just the whole radio and stuff....

As I stated previously in this thread you can protect sensitive circuitry from EMP using transorb diodes connecting entrance points in the circuitry to ground. They are little diodes that have a cutoff voltage, and when a surge comes in higher than the cutoff the diode opens up and lets the surge drain safely to ground without entering the rest of the circuitry.

Both forms of EMP (magnetic field collapse and uwave discharge) can also be made directional with proper waveguides and antenna, however there is always some sideband radiation.

Originally posted by apc
As I stated previously in this thread you can protect sensitive circuitry from EMP using transorb diodes connecting entrance points in the circuitry to ground. They are little diodes that have a cutoff voltage, and when a surge comes in higher than the cutoff the diode opens up and lets the surge drain safely to ground without entering the rest of the circuitry.

Both forms of EMP (magnetic field collapse and uwave discharge) can also be made directional with proper waveguides and antenna, however there is always some sideband radiation.

So your going to ground all the radios, flash lights, engine ignitions and head lights?
That bit about direction....didnt know about that...can you explain further?

[edit on 26/02/2005 by devilwasp]

Originally posted by devilwasp

Originally posted by warpboost
Maybe they are shielded?

.....I thought about it but in my opinion not really woth it, if its on the back of a humvee the electromagnet shielding or faraday cage will be useless since all it would do was contain the pulse.

You would only have to put the faraday cage around the things you want protected, therefor if you embedded a faraday cage in the body of the Humvee and mounted the EMP to the top (on the outside of the cage) then it wouldn't contain the pulse (unless of course the mechinism itself needed to be shielded in which case make it a 1-time-use weapon or have replacement parts [like an artilary shell]).

Originally posted by SwitchbladeNGC
You would only have to put the faraday cage around the things you want protected, therefor if you embedded a faraday cage in the body of the Humvee and mounted the EMP to the top (on the outside of the cage) then it wouldn't contain the pulse (unless of course the mechinism itself needed to be shielded in which case make it a 1-time-use weapon or have replacement parts [like an artilary shell]).

You first need a purpose humvee, then you need to find a way for the emp not to go through the wires to the actual generator of the pulse.