Electro-magnetic pulse

[turtlevette]

Originally Posted By: Garak

Perhaps he can do some original research, then, and submit it for peer review. Unfortunately, original research in this domain is just about impossible, and since he doesn't like anyone having a bibliography, we should obviously take his word for it.


But suddenly you're some sort of expert in this field? I thought you drove cabs? I'm the most qualified of anyone posting in this thread. Classes in nuclear engineering experience at nuclear power plants, experience in VLSI, CMOS design, colaboration with engineers at Raytheon, experience in microprocessor based relay testing...

You know a laptop gets x rayed hundreds of times at airport security and that doesn't kill a thing. X rays and gamma are very similar.

Tell me how gamma is going to kill an alternator. The rectifiers in there are huge. Tell me how gamma is going to induce any voltage in a wire.

You keep saying Maxwells equations over and over.

But this is the crazy world of car forums where someone with a lot of posts think they're some sort of ultimate authority on everything. And then they get all their buddies to come in and talk garbage. Since its 6 against 1 I guess that makes science on your side. This is not a popularity contest.

 

[Garak]

Sunshine, I haven't driven a cab in decades, I drove them in the summer when I was in university and took care of the running and maintenance of the fleet outside of that narrow little window. And for the last time, the gamma rays don't kill anything. The point of origin of the pulse isn't even at the point of detonation!

The gamma rays interact with the ionosphere, which creates the N-EMP. The gamma rays aren't the N-EMP. There's a big difference. So, gamma rays won't kill an alternator or a laptop. No one suggested that. Gamma rays won't induce voltage in a wire, but magnetic flux sure as heck will, and 50,000+ volts/m is significant.

I keep saying Maxwell's equations over and over because if you looked at the integrals and the closed surface you'd see why you made an inverse square law gaffe in the first place. Did you not learn these equations? Never done a surface integral over a closed surface? A volume integral? With your obvious qualifications in this field, I'm at a loss as to why you are making elementary errors such as confusing gamma radiation with the N-EMP itself.

Obviously the Raytheon engineers of whom you speak know that carriers' electronics have been hardened against N-EMP for many, many years. Nuclear power plants don't tend to cause N-EMPs, either. So, quit bringing up matters that have absolutely nothing to do with the issue at hand. Airport security has nothing to do with this. That's a Turtlevette trademarked diversion. The same goes for the talk about gamma rays not damaging electronics. That's another Turtlevette trademarked diversion.

 

[turtlevette]

Originally Posted By: Garak


The gamma rays interact with the ionosphere, which creates the N-EMP.

The gamma rays aren't the N-EMP. There's a big difference. So, gamma rays won't kill an alternator or a laptop. No one suggested that. Gamma rays won't induce voltage in a wire, but magnetic flux sure as heck will, and 50,000+ volts/m is significant.




They interact with the ionosphere? Be more specific.

Magnetic flux does not carry over long distances. How are you coming up with numbers?

You're talking a bunch of gibberish trying to bluff. Integral over what surface?

So you have a PhD in physics? You work in the Canadian nuclear weapons program that they don't have?

What's the big secret? What did you study at "university"


Yea, I just looked at the Wikipedia and I'm seeing keywords you're using. Copy and paste. You had me going...

 

[Shannow]

Turtlevette,
My high school Professor (actually from Calgary by birth) explained it all in high school language back in the 80s...Can't see how it can be so new and mystical to an experienced EE.

Gamma rays knock electrons into motion at relativistic speeds, which creates an electromagnetic "pulse", with a voltage gradiant that can fry sensitive recievers.

Remember when they taught you in the power station safety rules training about "hopping" away from a transmission line fault to Earth to eliminate the step voltage that may occur between your feet.

Quote:
A study conducted in the U.S. during the late 1980s reported that a high-yield device exploded about 500 kilometers above the ground can generate an electromagnetic pulse (EMP) of the order of 50,000 volts over a radius of 2,500 kilometers around the point of burst which would be collected by any exposed conductor. Such an attack will not cause any blast or thermal effects on the ground below but it can produce a massive breakdown in the communications system....It is certain that most of the land communication networks and military command control links will be affected and it will undermine our capability to retaliate. This, in fact, is the most powerful incentive for a preemptive attack. And a high-altitude exo-atmospheric explosion may not even kill a bird on the ground


That 50 KV is 50KV/m voltage gradient. 16,000 volts per foot.

 

[Garak]

How?

Originally Posted By: DOD MCTL, 1998
A high-altitude nuclear detonation produces an immediate flux of gamma rays from the nuclear reactions within the device. These photons in turn produce high energy free electrons by Compton scattering at altitudes between (roughly) 20 and 40 km. These electrons are then trapped in the Earth’s magnetic field, giving rise to an oscillating electric current. This current is asymmetric in general and gives rise to a rapidly rising radiated electromagnetic field called an electromagnetic pulse (EMP). Because the electrons are trapped essentially simultaneously, a very large electromagnetic source radiates coherently.

Magnetic flux does carry over long distances through the ionosphere. But what you said and what I said don't mean anything without quantifying it. What do you call long distances? In this topic, the flux carries (and causes damage) hundreds of kilometers away from the the point on the Earth directly below the point of detonation.

The shape of the Earth's ionosphere is a closed surface, that of a sphere. The double integral is done over that surface. Now, if you think that's gibberish, that means you simply don't understand it, and an engineer shouldn't have a lot of difficulty with that.

I do not have a PhD in physics. I studied physics and mathematics at university, and no, was not part of any nuclear program, obviously. Most people who were able to study real N-EMPs are long retired, if not long dead. We have to work with what they did.

You had to check Wikipedia to understand the math? I'm sorry to hear that. Engineering and Design - Electromagnetic Pulse (EMP) and Tempest Protection for Facilities, 1990, has all those messy integrals simplified down to basic algebraic expressions to give you the simple geometry of the matter, providing the radius calculation and converting it to surface area in a separate equation for those that are flummoxed by pi*r*r. I suppose this was done to make things more understandable to the Raytheon engineers.

 

[eljefino]

Originally Posted By: fdcg27
Originally Posted By: eljefino


And my w123 300d will suddenly become more relevant.

Even if its alternator goes kablooey, it'll roll-start without electricity.


Unless you happen to have a grey market stick 300D, you're going to need a really long hill to get it to start. While the automatic in these will allow a towed start and the OM's of the 240Ds I've had actually told you how to do it, you have to be going pretty fast to get a start, and the diesel won't be especially happy about starting without the help of the glow plugs.
Still, if you could get one of these old dears to run, you'd have no need for any alternator output.


So it looks like you have to tow it in neutral for a while to build up pressure from the rear pump before "going for it" and slamming it into low.

If glow plugs are dead, I've heard people will put little flaming strips of newspapers in their air cleaner area to get ingested into the motor to get things going. I can't verify, but find it interesting. How to keep these flaming things going for the two-mile pre-tow tow sounds like a challenge.

 

[fdcg27]

I think that if you can get the rear pump producing enough pressure to turn the engine over, it'll light off even without the glow plugs.
Using what might have been a leaf from a book you might have written, I jumped across a dead glow plug on one of my 240Ds with the glow plugs wired in series and the cylinder with the dead glow plug lit off after engine start.
You are well aware that a dead cylinder on a 240D would be unmistakable, since with all four burining it still feels as though only two are producing power.

 

[KrisZ]

Originally Posted By: Garak
How?

A high-altitude nuclear detonation produces an immediate flux of gamma rays from the nuclear reactions within the device. These photons in turn produce high energy free electrons by Compton scattering at altitudes between (roughly) 20 and 40 km. These electrons are then trapped in the Earth’s magnetic field, giving rise to an oscillating electric current. This current is asymmetric in general and gives rise to a rapidly rising radiated electromagnetic field called an electromagnetic pulse (EMP). Because the electrons are trapped essentially simultaneously, a very large electromagnetic source radiates coherently.


But you still have about 20 to 40 km of atmosphere to deal with, which will act as an insulator. Perhaps that is why solar flares, although in theory just as dangerous as an EMP, mostly go unnoticed by the general public?

 

[hattaresguy]

The 616/17 are not terrible cold blooded if they are in good shape they will start without glow plugs.

The later 603/6 series are pigs when cold, needs the glow plugs.

In an emergency you could shoot some either into the intake and roll it down a hill, it will start.

 

[Garak]

Originally Posted By: KrisZ
Perhaps that is why solar flares, although in theory just as dangerous as an EMP, mostly go unnoticed by the general public?

You don't get near the levels of flux with a solar flare, though. In one of the papers I quoted, they had a lengthy discussion about that. With respect to the insulating properties of the atmosphere, that's correct with respect to electricity, but doesn't do much against the magnetic field, or flux thereof.

 

[friendly_jacek]

Originally Posted By: Garak
Originally Posted By: KrisZ
Perhaps that is why solar flares, although in theory just as dangerous as an EMP, mostly go unnoticed by the general public?

You don't get near the levels of flux with a solar flare, though.


my understanding is that the high intensity solar flares like the 1859 "Carrington event" or the 2 ones in the 9th century would wipe out modern electric/electronic networks. supposedly, there is 12% chance one can happen between 2012-2020.

 

[HerrStig]

Originally Posted By: CT8
I had to come back to add though not scientific. The EMP needs a long run or wire to generate the voltage needed for damage I had a near hit by lightening several years ago. The house light up blinding bright , the chain link rattled and the thunder I thought would rip the house off the foundation. Everything went dark, I called the power company And the power company came by and replaced the fuses in the transformer and said if that didn't fix it a crew would come out the next day to replace the transformer. The fuses did the trick and this computer was the one I was on during the close lightening strike.
+1 Car alternator diodes are pretty hefty and shielded inside the car body --- unless you have a PLASTIC car.

 

[HerrStig]

Originally Posted By: R2d2
The show Mythbusters tested several modern cars on a military base with a emp pulse generator, the worst thing that happened was one car had a CEL come on but they were all drivable.
Jeepers, don't drag the facts into it. A certain German car comppany tests their products at a Voice of America transmitter site in North Carolina. They are allowed to drive though an antenna farm which is radiating a megawatt ERP.
The drivers have to wear shielded suits similar to those worn by high voltage transmission line workers. A steel car body is a Faraday cage. (You could look it up)

 

[friendly_jacek]

Originally Posted By: HerrStig
Originally Posted By: R2d2
The show Mythbusters tested several modern cars on a military base with a emp pulse generator, the worst thing that happened was one car had a CEL come on but they were all drivable.
Jeepers, don't drag the facts into it. A certain German car comppany tests their products at a Voice of America transmitter site in North Carolina. They are allowed to drive though an antenna farm which is radiating a megawatt ERP.
The drivers have to wear shielded suits similar to those worn by high voltage transmission line workers. A steel car body is a Faraday cage. (You could look it up)


i agree, but where do you get fuel in case of EMP/solar flare/cyber-war event? i can tell you from my post hurricane experience, no electricity = no fuel, no services, no modern life.

i'm watching the 2006 Jericho TV show on Netflix and while it's crudely made, some parts seem believable.

 

[Garak]

Originally Posted By: friendly_jacek
my understanding is that the high intensity solar flares like the 1859 "Carrington event" or the 2 ones in the 9th century would wipe out modern electric/electronic networks. supposedly, there is 12% chance one can happen between 2012-2020.

Yep, that matter comes up in the media once in a while. All I know is if we ever got hit with a N-EMP up here with the huge amount of long distance overhead lines, I can't see us having a good time of it.

As for the solar flares, the concern with those isn't about the peak so much, but the duration of the disruption to the field (as in a fusion device).

Originally Posted By: HerrStig
A certain German car comppany tests their products at a Voice of America transmitter site in North Carolina. They are allowed to drive though an antenna farm which is radiating a megawatt ERP.

I wonder what the voltage gradient would be.

 

[turtlevette]

Originally Posted By: Garak

I wonder what the voltage gradient would be.


Heck. Calculate it. Since you are so familiar calculating integrals over complex 3 dimensional shapes.

Or maybe you are just bsing us?

 

[Garak]

A Gaussian surface, as in our discussion of the Earth's magnetic field, is hardly a complex shape. In any case, just having a rough estimate of power is not sufficient. And here, this is an antenna farm with multiple sources. I wouldn't touch that with a ten foot pole. Nice try, though.

 

[KrisZ]

Originally Posted By: Garak
Originally Posted By: KrisZ
Perhaps that is why solar flares, although in theory just as dangerous as an EMP, mostly go unnoticed by the general public?

You don't get near the levels of flux with a solar flare, though. In one of the papers I quoted, they had a lengthy discussion about that. With respect to the insulating properties of the atmosphere, that's correct with respect to electricity, but doesn't do much against the magnetic field, or flux thereof.


But wouldn't the EMP signal be subject to the inverse square law once it entered the atmosphere? I think it would and hence that 40km region would essentially act as an insulator, diminishing the strength of the electro-magnetic field each meter it passed through the air.

Don't get me wrong, I do think that there would be an effect of such an event, our electrical grid probably being the major concern here, but I'm having a hard time believing that we would essentially go back to the industrial revolution age, with everything electrical/electronic being wiped out.

 

[Triton_330]

With Jesus you don't need to worry about EMPs affecting your car.



(Thought I'd lighten the mood here with that.)

~ Triton

 

[friendly_jacek]

Originally Posted By: KrisZ

But wouldn't the EMP signal be subject to the inverse square law once it entered the atmosphere? I think it would and hence that 40km region would essentially act as an insulator, diminishing the strength of the electro-magnetic field each meter it passed through the air.

Don't get me wrong, I do think that there would be an effect of such an event, our electrical grid probably being the major concern here, but I'm having a hard time believing that we would essentially go back to the industrial revolution age, with everything electrical/electronic being wiped out.


the square low applies to a point source emitting in all directions. think about bare bulb or omnidirectional antenna. this EMP would be emitted on the entire surface of the edge of atmosphere. think of infinite large reflector or infinite large array antenna.