EMPs and Faraday Cages

Just to spook you here is some history about an event that has come to be called the Carrington Event.

From August 28, 1859, until September 2, numerous sunspots were observed on the Sun. Just before noon on September 1, the English amateur astronomers Richard Carrington and Richard Hodgson independently made the first observations of a solar flare. It caused a major coronal mass ejection (CME) to travel directly toward Earth, taking 17.6 hours. Such a journey normally takes three to four days. This second CME moved so quickly because the first one had cleared the way of the ambient solar wind plasma.

Because of a simultaneous “crochet” observed in the Kew Observatory magnetometer record by Scottish physicist Balfour Stewart and a geomagnetic storm observed the following day, Carrington suspected a solar-terrestrial connection. Worldwide reports on the effects of the geomagnetic storm of 1859 were compiled and published by Elias Loomis which support the observations of Carrington and Stewart.

On August 29, 1859, aurorae were observed as far north as Queensland.

On September 1–2, 1859, the largest recorded geomagnetic storm occurred. Aurorae were seen around the world, even as far south as the Caribbean; those over the Rocky Mountains were so bright that their glow awoke gold miners, who began preparing breakfast because they thought it was morning. People who happened to be awake in the northeastern US could read a newspaper by the aurora’s light. The aurora was visible as far from the poles as Cuba and Hawaii.

Telegraph systems all over Europe and North America failed, in some cases giving telegraph operators electric shocks. Telegraph pylons threw sparks. Some telegraph systems continued to send and receive messages despite having been disconnected from their power supplies.

On Saturday, September 3, 1859, the Baltimore American and Commercial Advertiser reported, “Those who happened to be out late on Thursday night had an opportunity of witnessing another magnificent display of the auroral lights. The phenomenon was very similar to the display on Sunday night, though at times the light was, if possible, more brilliant, and the prismatic hues more varied and gorgeous. The light appeared to cover the whole firmament, apparently like a luminous cloud, through which the stars of the larger magnitude indistinctly shone. The light was greater than that of the moon at its full, but had an indescribable softness and delicacy that seemed to envelop everything upon which it rested. Between 12 and 1 o’clock, when the display was at its full brilliancy, the quiet streets of the city resting under this strange light, presented a beautiful as well as singular appearance.”

In June 2013, a joint venture from researchers at Lloyd’s of London and Atmospheric and Environmental Research (AER) in the United States used data from the Carrington Event to estimate the current cost of a similar event to the world economy at $2.6 trillion.

The estimation may seem ridiculously high because it is taking into account the entire electric grid across the nation which is not shielded or prepared for such an event.  At the time, in some cases, it melted wires right off the poles and left scorch marks on railroad ties from the current flowing through the rails.  In our day we would see massive turbines and generators go down, most any vehicle made in the last 25 years would go down, pretty much anything utilizing electric circuitry.  In cities that means city water is gone, city electric is gone, no food is entering the cities because trains and vehicles are down, and there is no way to get out except on foot with the other hundreds of thousands to millions ravaging the countryside for food (another good argument to get up on your food storage and hunker down for a while if the SHTF).

Ice cores contain thin nitrate-rich layers that can be analyzed to reconstruct a history of past events before reliable observations; the data from Greenland ice cores was gathered by Kenneth G. McCracken and others. These show evidence that events of this magnitude—as measured by high-energy proton radiation, not geomagnetic effect—occur approximately once per 500 years, with events at least one-fifth as large occurring several times per century. These similar but much more extreme cosmic ray events however may originate outside the solar system and even outside the galaxy. Less severe storms have occurred in 1921 and 1960, when widespread radio disruption was reported. The March 1989 geomagnetic storm knocked out power across large sections of Quebec.

With massive storms like that in the Carrington Event only occurring about every 500 years or so then we likely have several hundred years before we need to worry about a major event; although lesser events continue to effect out world with nominal impact.  Estimations are that a similar event could knock out the US for roughly a year before we get back on our feet as a nation.  Some doomsday prophesiers have stated that anywhere from 50 to 90% of the US population could die within that first and pivotal year.  Surprisingly, the underdeveloped nations are the ones that would be least impacted because they rely less on electronic technology.  So is there a way for man to manipulate these powers in a way to worry us?  In fact there is, and it is a real threat?  It’s called the nuclear electromagnetic pulse, or simply a massive EMP for short.

An electromagnetic pulse is a burst of electromagnetic radiation. Nuclear explosions create a characteristic pulse of electromagnetic radiation called a Nuclear EMP or NEMP.

Electromagnetic pulse is commonly abbreviated as EMP and pronounced by saying the three letters separately (E-M-P).

The resulting rapidly changing electric fields and magnetic fields may couple with electrical/electronic systems to produce damaging current and voltage surges. The specific characteristics of any particular nuclear EMP event vary according to a number of factors. The greatest of these factors is the altitude of the detonation.

In military terminology, a nuclear warhead detonated hundreds of kilometers above the Earth’s surface is known as a high-altitude electromagnetic pulse (HEMP) device. Effects of a HEMP device depend on factors including the altitude of the detonation, energy yield, gamma ray output, interactions with the Earth’s magnetic field and electromagnetic shielding of targets.

According to an internet primer published by the Federation of American Scientists

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.

The pulse can easily span continent-sized areas, and this radiation can affect systems on land, sea, and air. … A large device detonated at 400–500 km (250 to 312 miles) over Kansas would affect all of the continental U.S. The signal from such an event extends to the visual horizon as seen from the burst point.

Thus, for equipment to be affected, the weapon needs to be above the visual horizon.

The altitude indicated above is greater than that of the International Space Station and many low Earth orbit satellites. Large weapons could have a dramatic impact on satellite operations and communications such as occurred during Operation Fishbowl. The damaging effects on orbiting satellites are usually due to factors other than EMP. In the Starfish Prime nuclear test, most damage was to the satellites’ solar panels while passing through radiation belts created by the explosion.

For detonations within the atmosphere, the situation is more complex. Within the range of gamma ray deposition, simple laws no longer hold as the air is ionised and there are other EMP effects, such as a radial electric field due to the separation of Compton electrons from air molecules, together with other complex phenomena. For a surface burst, absorption of gamma rays by air would limit the range of gamma ray deposition to approximately 10 miles, while for a burst in the lower-density air at high altitudes, the range of deposition would be far greater.

Typical nuclear weapon yields used during Cold War planning for EMP attacks were in the range of 1 to 10 megatons (4.2 to 42 PJ) This is roughly 50 to 500 times the sizes of the weapons the Hiroshima and Nagasaki bombs. Physicists have testified at United States Congressional hearings that weapons with yields of 10 kilotons (42 TJ) or less can produce a large EMP.

The EMP at a fixed distance from an explosion increases at most as the square root of the yield (see the illustration to the right). This means that although a 10 kiloton weapon has only 0.7% of the energy release of the 1.44-megaton Starfish Prime test, the EMP will be at least 8% as powerful. Since the E1 component of nuclear EMP depends on the prompt gamma ray output, which was only 0.1% of yield in Starfish Prime but can be 0.5% of yield in low yield pure nuclear fission weapons, a 10 kiloton bomb can easily be 5 x 8% = 40% as powerful as the 1.44 megaton Starfish Prime at producing EMP.

The total prompt gamma ray energy in a fission explosion is 3.5% of the yield, but in a 10 kiloton detonation the triggering explosive around the bomb core absorbs about 85% of the prompt gamma rays, so the output is only about 0.5% of the yield. In the thermonuclear Starfish Prime the fission yield was less than 100% and the thicker outer casing absorbed about 95% of the prompt gamma rays from the pusher around the fusion stage. Thermonuclear weapons are also less efficient at producing EMP because the first stage can pre-ionize the air^[33] which becomes conductive and hence rapidly shorts out the Compton currents generated by the fusion stage. Hence, small pure fission weapons with thin cases are far more efficient at causing EMP than most megaton bombs.

This analysis, however, only applies to the fast E1 and E2 components of nuclear EMP. The geomagnetic storm-like E3 component of nuclear EMP is more closely proportional to the total energy yield of the weapon.

In nuclear EMP all of the components of the electromagnetic pulse are generated outside of the weapon.

For high-altitude nuclear explosions, much of the EMP is generated far from the detonation (where the gamma radiation from the explosion hits the upper atmosphere). This electric field from the EMP is remarkably uniform over the large area affected.

According to the standard reference text on nuclear weapons effects published by the U.S. Department of Defense, “The peak electric field (and its amplitude) at the Earth’s surface from a high-altitude burst will depend upon the explosion yield, the height of the burst, the location of the observer, and the orientation with respect to the geomagnetic field. As a general rule, however, the field strength may be expected to be tens of kilovolts per metre over most of the area receiving the EMP radiation.”

The text also states that, “… over most of the area affected by the EMP the electric field strength on the ground would exceed 0.5E_max. For yields of less than a few hundred kilotons, this would not necessarily be true because the field strength at the Earth’s tangent could be substantially less than 0.5E_max.”

(E_max refers to the maximum electric field strength in the affected area.)

In other words, the electric field strength in the entire area that is affected by the EMP will be fairly uniform for weapons with a large gamma ray output. For smaller weapons, the electric field may fall at a faster rate as distance increases.

And thus we have the man made effects of the Carrington Event.  So; beans and bullets aside, how do we save those data devises that in many cases define our lives?  Who wants to lose an external hard drive with the photos and videos documenting your family’s life?  What value might radios lend to you and your family; if you don’t know then take time to talk to a HAM Radio hobbyist.  The highest recommendation is a Faraday case.  From the Survival Mom Why and how to protect your gear from EMP:

The Faraday cage is named after Michael Faraday, the scientist who discovered its properties for shielding against electromagnetic waves, including electricity. You can build simple Faraday cages at home at a very low cost that will work just as well as the expensive ones that the government uses. All it takes is some common household items.

 

A Faraday cage protects its contents by preventing electromagnetic energy from getting inside. Expensive Faraday units use a combination of a fine copper mesh and solid aluminum. You can build your own at home using aluminum foil and a galvanized steel trash can. By the way, Faraday shielding doesn’t actually have to be a cage, it’s simply anything that blocks electromagnetic radiation.

There are lots of places on the Internet claiming that all you need to do is put your gear into a microwave oven or Mylar bag and it will be protected from EMP. It would be wonderful if these worked, but unfortunately, I am highly skeptical of them. You can easily to test these and see for yourself.

The frequencies for EMP range from approximately AM radio to approximately FM radio (actually, EMP frequencies have a much broader range, but the AM/FM radio comparison is close enough). AM signals go as low as 540 kHz and the FM radio band stops at 108 MHz. Don’t worry if those frequencies don’t mean anything to you. The important thing to know is that you can test how effective a container will work at shielding electromagnetic frequencies, simply by using an AM/FM radio.

First, tune the radio to a strong FM station and turn up the volume. Put it into the Faraday cage you’re testing and listen to see if the radio station is still being picked up by the radio. Don’t get too excited if it doesn’t, as FM signals are very easy to shield against.

Next, tune the radio to a strong AM station and retest. The low frequency of AM signals are very good at penetrating objects. If you can’t hear the AM station anymore, that’s a good sign. Anything that can block strong AM and FM radio signals would probably make a good Faraday cage. Keep in mind, though, that the power of these signals in your home are relatively weak (unless you happen to live under a radio tower).

This is important to know because you will see videos online where people put their cell phones into a microwave, Mylar bag or some other type of “Faraday” protection and demonstrate the effectiveness by showing how the cell phone loses the WiFi and cell tower signals.

Cell signals are extremely weak to begin with and are very easy to block. These demonstrations are not good tests for protecting against EMP. A food grade Mylar bag won’t even stop 11 watts of WiFi signal (a 2.4 GHZ frequency) from reaching my iPhone when it’s right next to the wireless router. It certainly won’t stop the destructive pulse from EMP.

To start, here’s a few things to keep in mind:

If you jump on the website http://thesurvivalmom.com/2012/10/18/why-and-how-to-protect-your-gear-from-emp/ there are some amazing photos and ideas for specific pieces of equipment.  A lot of the historical info and EMP info was pulled from various Wikipedia pages if you are curious and want to do additional reading on the topic.  Thanks for reading.

Jon