Electromagnetic Pulse (EMP)

Hydrogen_bomb_and_nuclear_tests_in_space. — Hydrogen bomb and nuclear tests in space.

Hydrogen bomb and nuclear tests in space.

Electromagnetic spectrum

The scientific phenomena

An electromagnetic pulse (Aka- transient electromagnetic disturbance) is a short burst of natural or artificial electromagnetic radiation. The term 'Electromagnetic pulse' is commonly abbreviated as E.M.P. and refers to a Electromagnetic phenomenon akin to static electricity, the hissing made on analogue radios by an unshielded motor and lightning. It may occur in the form of a radiated, electric or magnetic field or conducted electrical current depending on the natural or man made source. It can kill satellites, TVs, transformers, computers, etc... Exploding nukes also cause it, especially when done in the outer atmosphere.

Making it happen

Nuclear explosions create a characteristic pulse of electromagnetic radiation called a Nuclear EMP or NEMP. When a nuclear warhead detonated several hundreds of kilometres above the Earth's surface is known as a high-altitude electromagnetic pulse (HEMP) device, but it's effectiveness depends 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. The HEMP acronym often being pronounced as one syllable. EMP interference is generally more disruptive or damaging to integrated circuits than vacuum tubes. Exploding nukes also cause it, especially when done in the outer atmosphere. Several satellites inadvertently damaged or destroyed by the in the Starfish Prime high-altitude nuclear test of July 9, 1962, and subsequent long turn temporary radiation belt.

The Starfish Prime high-altitude nuclear test event

Operation Dominic Starfish-Prime nuclear test from plane — The debris fireball and aurora created by the Starfish Prime test, as seen from a KC-135 aircraft at 3 minutes on July 9, 1962. Yield 1,450 kilotons.

Nukes_in_Space-The_Rainbow_Bombs — Nukes in Space-The Rainbow Bombs

Nukes in Space-The Rainbow Bombs.

Several satellites inadvertently damaged or destroyed by the in the Starfish Prime high-altitude nuclear test of July 9, 1962, and subsequent long turn temporary radiation belt.

A total of 7 satellites failed over the months following the test as radiation damaged their solar arrays or electronics, including the first commercial relay communication satellite, Telstar. just under 1/3 of all low orbit satellites were inoperative after the test created a temporary artificial radiation belt. Detectors on Telstar, TRAAC, the Injun 1 and Ariel 1 were used to measure distribution of the radiation produced by the tests, of which only the Injun 1 survived. Ariel 1, TRAAC, and Transit 4B were destroyed, while Kosmos 5, Injun II and Telstar 1 suffered minor damage by radiation on solar cells and alike. Telstar finally shorted out after 3 months.

The then only theoretical Electromagnetic Pulse (EMP) hit Honolulu and New Zealand (approximately 1,300 kilometers away), fusing 300 street lights on Oahu (Hawaii), setting off about 100 burglar alarms and causing the failure of a microwave repeating station on Kauai, which cut off the island's sturdy local telephone system from the other Hawaiian islands.

The Soviet's Tsar Bomba bast on October 30, 1961, also caused a 1 hour local radio jamming effect due to the initial ionised radiation output.

Most weponolagists, scientists, military leaders and politicians on both sides found this level of collateral damage frightening.

Weapons ideas

THE_INVISIBLE_MACHINE_-_ELECTROMAGNETIC_WARFARE-0 — THE INVISIBLE MACHINE - ELECTROMAGNETIC WARFARE-0

THE INVISIBLE MACHINE - ELECTROMAGNETIC WARFARE.

EMP will, like lighting and static electricity, interference with electrical goods. In generally it is more disruptive or damaging to integrated circuits than to valves\vacuum tubes. The resulting rapidly changing electric and magnetic fields may coupled with exposed electrical/electronic systems can produce damaging current and voltage surges. The damaging effects of high-energy EMP have been used to create EMP, weapons. These are typically divided into nuclear and non-nuclear devices. It can kill satellites, TVs, transformers, computers, etc...

Popular culture

Such weapons, both real and fictional, are becoming known to the public by means of popular culture. The greatest factors influencing such a bomb are the blast yield and the altitude of it's detonation.

Popular myths and common misconceptions

A 2010 technical report written for the US government's Oak Ridge National Laboratory included a brief section addressing common EMP myths. The remainder of the section is a direct quotation from that Oak Ridge report regarding common HEMP Myths:

Much of the literature on HEMP is either classified or not easily accessible. Probably because of this, some of what is openly available tends to vary in accuracy – some, especially from the Internet, has major inaccuracies. Some discussions of HEMP have the right words and concepts, but do not quite have them put together right, or have inaccurate interpretations. Here we will discuss some common misunderstandings. HEMP has also appeared in some movies, and there are on-line discussions about possible errors in their depiction of HEMP. Here we will be concerned with E1 HEMP, and ignore misunderstandings about other types of EMP.

Extremists: Some general emphasis of comments fall into either “the world as we know it will come to an end” if there is a high altitude nuclear burst, or the other extreme: “it’s not a big deal, nothing much will happen”. Since we really have never had a nuclear burst over anything like our current modern infrastructure, no one really knows for sure what would happen, but both extremes are not very believable.
Yield: There appears to be an assumption that yield is important – it is not for E1. The assumption that E1 is an issue only for cold war type situations, but not for terrorists or rogue nations, is false. Very big bombs might have better area coverage of high fields by going to higher burst heights, but for peak fields the burst yield is only a very minor consideration.
1962 experience: Some point to the Starfish event, and the rather minor HEMP effects produced at Hawaii by it. However, there are many problems with extrapolating that experience:
1. That was about half a century ago. Since then, the use of electronics has increased greatly, and the type of sensitive electronics we currently use did not really exist back then.
2. The burst was fairly far away from Hawaii, and the incident E1 HEMP was much less than a worst case scenario case.
3. The island has small size. If used over the continental U.S., the long transmission lines would be exposed (especially an issue for late-time HEMP). In addition, widely separated substations would have been exposed, although with electromechanical relays (not solid state). Also the yield argument has been used – Starfish was a very big weapon, yet it did very little – see the previous item, yield is not really very significant.
Cars dying: Some say that all vehicles traveling will come to a halt, with all modern vehicles damaged because of their use of modern electronics (and one movie even had a bulky, non-electronic part dying). Most likely there will be some vehicles affected, but probably just a small fraction of them (although this could create traffic jams in large cities). A car does not have very long cabling to act as antennas, and there is some protection from metallic construction. As non-metallic materials are used more and more in the future to decrease weight and increase fuel efficiency, this advantage may disappear. Some things like the doors suddenly falling off or the doors jamming shut when using a mechanical lock and key system rather than an electrical key phob based systen is just stupid and\or for comic effect in a movie's context.
Wristwatch dying: One movie critic pointed out that electronics in a helicopter were affected, but not the star’s electronic digital watch. A watch is much too small for HEMP to affect it. Windup clockwork watches and clocks dying is just stupid and\or for comic effect in a movie's context.
Electrons present: One critic, with some awareness of the generation process, said that HEMP could not be present unless there were also energetic electrons present. This is true when one is within the source region, which exists for all types of EMP – there are energetic electrons present. However for the HEMP, the radiation and energetic electrons are present at altitudes of 20 to 40 km, not at the ground.
Turn equipment off: There is truth to this recommendation (assuming if there was a way to know that a burst was about to happen). Equipment is more vulnerable if it is operating, because some failure modes involving E1 HEMP trigger the system’s energy to damage itself. However, damage can also happen, but not as easily, to systems that are turned off.
Maximum conductor length: There is a suggestion that equipment will be OK if all connected conductors are less than a specific length. Certainly shorter lengths are generally better, but there is no magic length value, with shorter always being better and longer not. Coupling is much too complex for such a blanket statement – instead it should be “the shorter the better, in general”. (There can be exceptions, such as resonance effects, which depend on line lengths).
Stay away from metal: There is a recommendation to be some distance away from any metal when a HEMP event occurs (assuming there was warning), because very high voltages could be generated. Metal can collect E1 HEMP energy, and easily generate high voltages. However, the “skin effect” (a term not really derived from the skin of humans or any other animal) means that if a human were touching a large “antenna” during an E1 HEMP event, any current flow would not penetrate into the body. Generally E1 HEMP is considered harmless for human bodies.

Electromagnetic Pulse (EMP)

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