08:58 – Thanks to everyone who made suggestions about finding books that are available under Kindle Unlimited. This link allows you to search only books that are available under that program. It wasn’t an option the last time I looked. Either that, or Amazon had it so well hidden that I couldn’t find it. I’ll probably sign up for the KU 30-day free trial later this week and give it a try.
More of the same today, building and shipping science kits. We’re trying to get ahead of things now. April is the worst month for sales, but summer is approaching fast. Sales volume will start to increase next month, climb further in June, and start going crazy in July. In all likelihood, there will be days in July and August when we ship more kits than we do in the whole month of April, so we have to be ready to meet that demand. That means not just building subassemblies and full kits, but getting purchase orders staged to get stuff ordered in time to arrive here when we need it, including allowances for stuff that’s backordered.
Re. EMP
I designed some stuff hardened (unclassified) against the Flashbulb of God. Basically it involved removing power for Gamma Dose Rate and component selection for Neutron.
Neutron hits Optoelectronics bad, loss of up to half of their brightness (so much for LED flashlights). Leakage current goes up some and analog circuits lose some accuracy.
Gamma causes latchup because all the transistors act like SCR (pnpn junctions) with the gate on the substrate. Limit power and/or remove power before the transitor burns up and you are fine.
So most electronics will still work because they are shut off or in low power mode. YMMV and past performance are no guarantee of future prophets.
I just barely understood that electronics stuff or at least the gist of it, but that “Flashbulb of God” intrigues me.
CME.
It was used in a John Ringo book to describe a nuclear explosion. I like it. 🙂
Aha!
Yeah, that could suck.
Regarding EMP, I had some involvement in that a long, long time ago. Some of it involved protecting military aircraft. At the time the concern was over composites replacing metals for construction. With no metal Faraday cage around some of the electronics, we worried about the effects of the EMP. Turned out that once we got over the fear, like all big problems, and I don’t mean to minimize this, careful design and attention to detail and testing actually yielded some good solutions.
I’m resisting the temptation to look up some references right now, but there’s likely not too much in open literature. Some of our work was based on assumptions at the time which may be out of date now. Perhaps we know more about the nature of EMP and CME events, but as Clayton says, the problem can be solved if there is a will.
I’ve never been too concerned about the local effects of EMP/CME. As you say, it’s easy enough to protect against, and in fact a lot of unprotected electronics would likely survive even worst-case scenario. The idea that nearly all vehicles except those produced before 1980 or so would be killed by an EMP/CME is pretty drastic worst-case thinking. I suspect that even most current-production vehicles would survive nearly any possible event. They might stall out and have to be restarted, but most of them aren’t going to be bricked.
I’ve actually had people tell me with complete seriousness than a small freighter-launched fission bomb could wipe out every electronic device including stuff like wristwatches and even cardiac pacemakers and that a Carrington-class CME would physically destroy things like electric motors that weren’t plugged in. It’s also true that very few non-technical preppers have much clue about EMP/CME in general, let alone understanding the huge differences between the two.
I’ve seen people claiming to have the technical chops to have a valid opinion (such as Ph.D.’s in electrical engineering) claim that a Faraday cage is useless unless it’s well grounded, and others with equal qualifications claim the exact opposite. EMP/CME is one of those things that scares a lot of people who hear about it, and books like One Second After don’t help matters.
What concerns me about both EMP and CME is the effect on our grid. Even if all your unconnected electronics survive undamaged, the same is not likely to be true for anything connected to long conductors, particularly high-voltage cross-country distribution lines. I’ve been told by people in a position to know that some work has been done on ameliorating such damage, but a lot remains undone.
“…particularly high-voltage cross-country distribution lines.”
Forget EMPs and CME’s; how ’bout some peeps shooting at those and/or blowing them up? From what I’ve seen over the decades, these are strung along some pretty off-the-beaten-path real estate, even here in the densely populated Northeast. I can hump up the street about a mile and then go in either direction through a lotta woods and over hill and dale and not run into any other homo sapiens sapiens. And overhead are all them wires strung between the towers.
“The idea that nearly all vehicles except those produced before 1980 or so would be killed by an EMP/CME is pretty drastic worst-case thinking.”
Cars, motorbikes, clocks, etc. All gone in an an instant unless it was sheilded military grade stuff like missile silos. I saw it in The Day After.
I saw it in The Day After.
Then it must be true.
Forget EMPs and CME’s; how ’bout some peeps shooting at those
Don’t go for the wires, go for the insulators. They are ceramic and will easily shatter and present a much larger target. Dropping the line will disable the feed. Don’t bother shooting transformers as those are fairly tough devices unless you are targeting the insulators on the top.
What concerns me about both EMP and CME is the effect on our grid.
I have an engineer friend that works for a power company with his expertise in serving extremely large clients, such as steel mills. He states that the grid is so large with so much electrical mass that it would take a seriously huge EMP to have any effect. The grid currently tolerates lightning strikes which induce much more power in the grid than an EMP would produce. Such strikes are absorbed with a circuit that trips and is generally fairly quick restored.
The necessary power to produce and a destructive electrical pulse in a single wire using nothing but inductance alone would be extremely difficult. Transformers have multiple windings for a reason along with the conductors being in close proximity to each other.
I think any EMP would be just a blip that will quickly be recovered.
The problem with an EMP is that the rise time is extraordinarily fast, much too fast to be clamped or dissipated by electronic surge/spike protectors.
The problem with an EMP is that the rise time is extraordinarily fast, much too fast to be clamped or dissipated by electronic surge/spike protectors.
Yes, but it may be more localized than we think. The natural impedance in the grid may slow the rise time, sort of a low pass filter effect. I’m sure that there is data on this, but probably not in the open literature. For example, the Tempest shielding spec is classified and sort-of compartmented.
Good nooz, finally:
Tax Advocate called here this noon and told me the IRS Gestapo faxed the levy/lien release order to both our bank and wife’s employer down in Mordor. She said she tried to contact me Friday so we wouldn’t worry over the weekend but I don’t recall seeing any vm’s or hearing the phone ring then. In any case she said, and the bank said, after I called them, that it takes 24-48 hours for it to take effect. So it should be OK tomorrow AM, supposedly. And the IRS can take our money instantly but it takes a shitload of hoops to jump through and at least two weeks to get it back again, even when it’s THEIR fucking mistake. Cocksuckers.
If youse ever run into shit with the IRS, be sure your first call is to your local IRS Tax Advocate; they work for the IRS but are supposed to be solidly objective and go to bat for taxpayers. This one did up here.
There is some interesting EM stuff here:
ELECTROMAGNETIC ENVIRONMENTAL EFFECTS
REQUIREMENTS FOR SYSTEMS
http://www.tscm.com/MIL-STD-464.pdf
And Tempest stuff here:
http://www.jammed.com/~jwa/tempest.html
Detailed Tempest Red/Black installation guidelines:
https://www.wbdg.org/ccb/FEDMIL/hdbk232a.pdf
This is not the unclass document the Air Force used to have online that I used in installation, it looks like it is quite a bit more detailed. It has a whole section on EMP.
nick
The problem with an EMP is that the rise time is extraordinarily fast
Lightning is also fast, speed of light. I doubt an EMP is any faster unless the laws of physics have been broken. I also don’t think the generated power will be huge as you are dealing with an inductor that is a single wire, long, but still a single wire. The physical spread of the EMP would have to be hundreds of miles to induce significant current. Not all the wires would be parallel with some at 90 degrees. The phasing would not be consistent thus reducing the surge. You may lose a few transformers, a capicator bank or two, a few fuses with the mass of the system absorbing much of the surge.
Only testing I have read about is localized to small systems, little effective mass and a highly concentrated pulse designed to cause a failure.
Uh, I was talking about rise time, which for EMP is in fact much faster and reaches a much higher voltage than a bolt-on-metal lightning strike.
And this should put the grounding question to rest:
“Grounding and bonding. The previously described principles arc of
little or no consequence if proper grounding and bonding techniques have not
been used. The goal of all grounding and bonding techniques is to redirect
the EMP into the earth. Thus, an effective earth electrode subsystem (EESS)
is required, with positive bonds to the shield, positive bonds between
elements of the shield, and protective components coupled to the shields.
Guidance for grounding and bonding is given in MIL-HDBK.419”
From the tempest document section on emp.
nick
@Ray, see the charts comparing rise time in the linked docs.
EMP’s faster rise time is specifically cited as a problem. So says Uncle….
nick
IIRC, for EMP the peak voltage can exceed 50 KV/m and peaks in < 5 ns
Glasstone’s “Effect of Nuclear Weapons” 3rd ed. 1977 devotes Chapter 11 to EMP effects, but Chapter 8 is also useful as it discusses the effect of neutrons and gamma radiation on semiconductors. http://www.fourmilab.ch/etexts/www/effects/ among many other sources for this book.
Google Starfish Prime for some older reports on EMP from south Pacific high altitude tests..
There’s a significant difference in rise time between a nuclear induced EMP (fast) and a solar flare (slow). This has some important consequences for electronic equipment survival. Painting with a broad brush, depending on the rise time, the ultra slow solar flares induce earth current at near DC into power lines. This can cause extremely high voltages and also may damage large distribution transformers as they are not intended to handle DC. (The DC current can, if sufficiently large, saturate the transformer core and reduce the transformer’s magnetizing inductance. This will then cause excessive AC current to flow.) While protective relays of the correct design may do a great deal to ameliorate this problem, it has caused significant outages in the past, such as in the Province of Quebec in 1989.
A fast rise EMP such as from a large thermonuclear weapon a couple hundred miles above ground, however, can have fast rise time, on the order of 1us or less–in some cases a few ns. This fast rise can induce large voltages on short lengths of wire and zap IC inputs. As semiconductor sizes have decreased over the last few decades, IC designers have added some electrostatic discharge protection to the devices, such as clamping diodes. However, these are often rated at only a few kV, but presumably would provide some degree of fast rise EMP protection.
Glasstone’s figure 11.50 shows the induced current into a high voltage electrical distribution line, with a peak of over 10 KA which is reached in 1us or less. Lightning has a fast voltage rise (0.25us or so) but the current waveform is much slower, usually around 8us. It’s not clear to me that normal lightning protection measures would easily deal with the faster rise EMP current waveform. On the other hand, the power generated is the time integral of the voltage and current, so the net power into a HV distribution circuit may not differ so much.
As far as grounding or not grounding a Faraday enclosure goes, if you have a rise time typical of a man-made EMP, less than 1us, I don’t see how a ground would make much difference; the ground wire has to be considered as a transmission line which has an impedance depending on length and frequency.
However, the principle upon which a Faraday enclosure works is that the external E field induces a current in the outer enclosure surface which cancels the external electromagnetic field. The degree of cancellation depends on the conductivity of the enclosure and also the frequency; at sufficiently low frequency, the enclosure wall will pass the field through (skin depth). This is probably not a serious problem unless you are down near DC or audio frequencies (solar flare) but the good news then is that the field may not be strong enough to induce damage levels of current or voltage on small electronics devices.
This all assumes that the Faraday enclosure does not have gaps in the shielding.
”
This all assumes that the Faraday enclosure does not have gaps in the shielding.”
The linked document provides mitigating strategies for openings and conductive penetrations.
The ground wire is presumed to be as short as practical, and I guess that makes it less subject to becoming a conduit for the EMP.
I’ve worked in spaces designed to meet TEMPEST requirements and installed and modified equipment to meet the requirements. It is very expensive and difficult to do, so I’m assuming it works, or it wouldn’t still be used. (of course, that line of reasoning can’t always be applied to Uncle.) From the linked dox, other than magnitude, TEMPEST and EMP countermeasures are pretty much identical in approach.
nick
On a related note, we have this from a security industry trade magazine:
Emphasis added.
nick
The idea that you need to ground a Faraday cage is nonsense. What you get with an ungrounded Faraday cage that is hit by some surge or EMP is that the whole thing is at an elevated voltage — which does not matter for anything inside.
This is so even when defending computers / electronics in practice, where you don’t have a thorough Faraday cage, but rather a Faraday cage with electrical penetrations through it. Those penetrations need to be defended. Each penetration may have power or signal, and will have a ground; the ground should be bonded to the cage, and some sort of surge suppression put on the power and signal lines (right at the entrance point to the cage; putting it farther inside or outside is a mistake) to prevent them from rising too far above ground. But the ground itself (and cage) can rise as much as it wants above the local earth ground.
Now, as a matter of electrical safety, it is best for the Faraday cage to be connected to the building ground, for the same reason that the metal shells of refrigerators and washing machines are grounded. This is to stop people from getting shocked in the event that a power wire shorts to the cage. But this is a precaution against everyday human error, not against EMP.
As for rise times of 5 nanoseconds, that’s not really a big deal. Yes, it’s faster than MOVs trigger; but a minor amount of series inductance will slow that down quite nicely, especially if followed by capacitance to ground. Those things are a standard feature of power supplies; they’re pretty much required by regulations which are designed to prevent power supplies from feeding high-frequency noise into the AC mains. They also work the other way, preventing high-frequency components (as in the fast-rise-time components of EMP) from getting into the power supply.
Now, when it comes to equipment where high-frequency signaling is part of the design spec, that’s another matter. Those things don’t have inductance and capacitance to kill high frequencies, because high frequencies are an inherent part of their operation. So broadband Internet is likely to be the first casualty. On the other hand, those wires are well shielded, as they need to be so that they don’t emit noise and clog the radio spectrum; and again, that shielding works both ways… except that this matter of shielding does get a bit complicated. An EMP isn’t going to put a big differential voltage on coaxial cable or on twisted pair, but it can and will put a big common mode voltage on them; and if large enough, that can do damage. Ethernet ports are protected against common mode voltages of up to 300 volts, but that’s not much in an EMP context; I’ve seen Ethernet ports fried by ordinary nearby lightning strikes, and that just for Ethernet lines within a single house. (The rest of the equipment was fine; just the ports that had been connected no longer worked.) Now, you can actually put a ferrite clamp around a high-speed cable in such a way that it blocks common-mode signals but not differential signals — in fact, that’s the normal thing you get when you put a ferrite clamp around the whole cable; you don’t need to do anything special. It adds inductance which kills high-frequency common-mode components but doesn’t molest differential-mode components. But this is not routinely done. It could be, and wouldn’t cost much; it just doesn’t happen to be.
By the way, don’t let those free-field figures like 50 kilovolts/meter scare you too much. The ordinary everyday electric field surrounding us (from sky to ground) is something like a hundred volts per meter. But you can hardly get any current out of that field, so we don’t perceive it. To measure it, you need an electrometer (which draws hardly any current); an ordinary multimeter with 10 megohm input resistance can’t measure it at all. In thunderstorms, that field number gets much higher, but still causes no problems until the actual lightning strike (which of course if it hits gives you the mother of all problems). Anyway, this is the context in which to read EMP figures of 50 kilovolts/meter; yes, there is this voltage, but it is at a very high impedance. It wouldn’t, for instance, do to you anything nearly like what a seven kilovolt power line dropping on your head would do (though that would only be three and a half kilovolts per meter).
Anyway, there was an EMP commission report that came out in 2008 which was pretty good. They did a bunch of tests on cars, for instance, and found that nothing particularly dire happened to them.
http://www.empcommission.org/
There are EMP’s and CME’s and then there are Murkan election charades and follies.
“If there is to be any hope of restoring our freedoms and reclaiming control over our government, it will rest not with the politicians but with the people themselves. When all is said and done, each American will have to decide for themselves whether they prefer dangerous freedom to peaceful slavery.”
Reasons not to vote:
https://www.lewrockwell.com/2015/04/john-w-whitehead/ignore-the-presidential-election/
The wife and I are at an engineering conference in San Antonio with 3,000 engineers. Plus half of them brought their significant others. You would never imagine that oil and gas prices have crashed. Of course, we all work in downstream, not downhole.
The various companies, 30 parties in all, had four live bands plus open bars and food. No sign of cutbacks here at the two Mariott hotels on the Riverwalk.
I have noticed that all of my friends here are getting old and fat. Ok, fatter. Plus, the number of lady engineers may be up to 20 percent. A lot of engineers are getting ready to retire and the new generation is very different. The world is changing.
“The idea that nearly all vehicles except those produced before 1980 or so would be killed by an EMP/CME is pretty drastic worst-case thinking.”
All I can say about this is to relay a bit of practical experience. A few years ago my Mazda Miata was in an open parking lot while I was at work when it was struck by a bolt of lightning, which I saw from my third floor classroom. I expected to find a dead car, but what actually happened was that some of the i/o ports on the computer that controlled the odometer and instrument panel were damaged, the cruise control computer was fried and a wire to one of the headlights was melted. The main engine control computer was fine and the car was drivable. I replaced the two computers using parts from a junkyard and the and the car has been fine ever since. The only lasting result was that my odometer got set back to zero.
As far as Faraday cages are concerned, they are based upon the idea that the electric field inside a closed, electrically conducting surface is always zero, assuming no net static charge exists inside the closed surface. The charges on the surface of the conductor will automatically arrange themselves so that this is so. However the mathematics assumes static or at least quasi-static conditions. If the rise time of an external field is smaller than the time it takes the charges on the closed surface to rearrange themselves, things get complicated. The only difference between a grounded and ungrounded Faraday cage is that the closed surface in an ungrounded cage can have a net charge, but the E-field inside the closed surface is still zero. Of course, if things change rapidly enough this doesn’t describe what really happens.
Thanks. I’ve read all of the publicly available documents on EMP/CME effects, but again I’m not an EE or physicist.
Sort of reminds me of the Y2K scare where people thought their cars would no longer function because the vehicles had a computer. All very much a concern until I asked them when was the last time they informed their vehicle of the date and time and that without such relevant information the car computer had no idea what day it was and thus had zero knowledge of Y2K. Generally all I got were blank stares.
OFD wrote:
“Reasons not to vote:”
Nah, vote for OFD for President!
Faraday cages do differ from ideality, but it’s not correct that high frequencies give them a problem — not until you get up to frequencies where the wavelength is smaller than the mesh of the cage. Microwave ovens, for instance, keep their microwaves inside them via a Faraday cage, and that’s at 2.4 GHz. (By the principle of reciprocity, anything that keeps electromagnetic radiation in will also keep it out.) In comparison, a rise time of 5 nanoseconds corresponds to a top frequency of about 50 MHz. In fact, with Faraday cages, slowly-changing magnetic fields are the EM fields that penetrate them most easily; to repel a constant magnetic field, you need a constant loop of current in the cage’s wall, and except in the case of superconductors, the loop will die out.
That’s also the biggest non-ideality when it comes to the sorts of frequencies in an EMP: the assumption that goes into the math is that the Faraday cage is made from a perfect conductor, with zero resistance. But the implications of this are just that you can’t make a good Faraday cage from tiny, thin wire, or from ultra-thin metalization on foil; it has to have some beef to it.