2006

11/9

Uncategorized

Whizz. Bang.

by | Print
{mosimage}

Fungus talks about the fearsome EMP.

Location: Hawaii. Time: Sometime in July 1958. One evening 100 burglar alarms suddenly sounded and 300 street lights suddenly blinked out for no apparent reason. All over the region, phones, radios, and televisions went dead without warning.

The cause, it turned out, was 800 miles due west and 250 miles up in the air: A 1.4 megaton nuclear weapon had been detonated some 1.32 million feet above tiny Johnston Island in the Pacific. It was a planned test, but what the U.S. military hadn’t anticipated was high-energy electrons subsequently bombarding a large swath of the Earth’s surface, crippling thousands of electrical circuits. Oops. (The same electrons also knocked out one-third of the satellites in low Earth orbit at the time, including Telstar, the very first operational communications satellite.) That test is when weapons engineers first realized that nukes were not just good for blowing up and melting stuff. They could also knock out electronics far in the distance.

Welcome to the world of EMPs.

Many of us may have been introduced to Electro-Magnetic Pulses through the 1999 cult-classic, The Matrix where they are the only weapons the rebels have against the Sentinels. EMPs are also depicted in Ocean’s 11 and the television series Dark Angel. But EMPs are neither as benign or romantic as they are made out to be on the silver screen.

The worst of the pulse lasts for only a second, but any unprotected electrical equipment — and anything connected to electrical cables, which act as giant lightning rods or antennas — will be affected by the pulse. Fluorescent lights and television sets will glow eerily bright, despite being turned off. The aroma of ozone mixed with smoldering plastic will seep from outlet covers as electric wires arc and telephone lines melt. Your Palm Pilot and MP3 player will feel warm to the touch, their batteries overloaded. Your computer, and every bit of data on it, will be toast. And then you will notice that the world sounds different too. The background music of civilization, the whirl of internal-combustion engines, will have stopped. Save a few diesels, engines will never start again. You, however, will remain unharmed, as you find yourself thrust backward 200 years, to a time when electricity meant a lightning bolt fracturing the night sky. Older, vacuum tube (valve) based equipment is much less vulnerable to EMP; Soviet cold war era military aircraft often had avionics based on vacuum tubes. There are a number of websites that explore methods for protecting equipment in the home or business from the effects of an EMP attack.

It is important to note that many nuclear detonations have taken place using bombs dropped by aircraft. The aircraft that delivered the atomic weapons at Hiroshima and Nagasaki did not fall out of the sky due to damage to their electrical or electronic systems. This is simply because electrons (ejected from the air by gamma rays) are stopped quickly in normal (dense) air for bursts below 10 km, so they don’t get a chance to be significantly deflected by the Earth’s magnetic field (the deflection causes the powerful EMP seen in high altitude bursts), but it does point out the limited use of smaller burst altitudes for widespread EMP.

An electromagnetic bomb or E-bomb is a weapon designed to disable electronics on a wide scale with an electromagnetic pulse. The electromagnetic radiation from an explosion (especially nuclear explosions) or an intensely fluctuating magnetic field is caused by Compton-recoil electrons and photoelectrons from photons scattered in the materials of the electronic or explosive device in a surrounding medium. The resulting electric and magnetic fields may couple with electrical/electronic systems to produce damaging current and voltage surges. This produces immense heat that simply fries the circuitry inside and destroys them. As such, while not being directly responsible for the loss of lives, these weapons are capable of disabling electronic systems on which industrialized nations are highly dependent. The effects are usually not noticeable beyond the blast radius unless the device is nuclear or specifically designed to produce an electromagnetic shockwave.

The theory behind the E-bomb was proposed in 1925 by physicist Arthur H. Compton–not to build weapons, but to study atoms. Compton demonstrated that firing a stream of highly energetic photons into atoms that have a low atomic number causes them to eject a stream of electrons. Physics students know this phenomenon as the Compton Effect. It became a key tool in unlocking the secrets of the atom.

Ironically, this nuclear research led to an unexpected demonstration of the power of the Compton Effect, and spawned a new type of weapon. In 1958, nuclear weapons designers ignited hydrogen bombs high over the Pacific Ocean. The detonations created bursts of gamma rays that, upon striking the oxygen and nitrogen in the atmosphere, released a tsunami of electrons that spread for hundreds of miles. Street lights were blown out in Hawaii, as previously mentioned, and radio navigation was disrupted for 18 hours, as far away as Australia. The United States set out to learn how to "harden" electronics against this electromagnetic pulse (EMP) and develop EMP weapons.

America has remained at the forefront of EMP weapons development. Although much of this work is classified, it’s believed that current efforts are based on using high-temperature superconductors to create intense magnetic fields. What worries terrorism experts is an idea the United States studied but discarded–the Flux Compression Generator (FCG)

An FCG is an astoundingly simple weapon. It consists of an explosives-packed tube placed inside a slightly larger copper coil. The instant before the chemical explosive is detonated, the coil is energized by a bank of capacitors, creating a magnetic field. The explosive charge detonates from the rear forward. As the tube flares outward it touches the edge of the coil, thereby creating a moving short circuit. The propagating short has the effect of compressing the magnetic field while reducing the inductance of the stator (coil). The result is that FCGs will produce a ramping current pulse, which breaks before the final disintegration of the device. Published results suggest ramp times of tens of hundreds of microseconds and peak currents of tens of millions of amps. The pulse that emerges makes a lightning bolt seem like a flashbulb by comparison.

The Indian military has studied FCG devices in detail because it fears that Pakistan, with which it has ongoing conflicts, might use E-bombs against the city of Bangalore, a sort of Indian Silicon Valley. An Indian Institute for Defense Studies and Analysis study of E-bombs points to two problems that have been largely overlooked by the West. The first is that very-high-frequency pulses, in the microwave range, can worm their way around vents in Faraday Cages. The second concern is known as the "late-time EMP effect," and may be the most worrisome aspect of FCG devices. It occurs in the 15 minutes after detonation. During this period, the EMP that surged through electrical systems creates localized magnetic fields. When these magnetic fields collapse, they cause electric surges to travel through the power and telecommunication infrastructure. This string-of-firecrackers effect means that terrorists would not have to drop their homemade E-bombs directly on the targets they wish to destroy. Heavily guarded sites, such as telephone switching centers and electronic funds-transfer exchanges, could be attacked through their electric and telecommunication connections.

EMPs may evoke awe and speculation. But to the world in the 21st century the over-riding emotion accompanying EMPs, and more specifically E-Bombs, is fear: Fear that the world could be set back 300 years to when electricity was not even a source of energy; Fear that the information on which this world runs could be obliterated at the whim of sufficiently dedicated madman. While there are some measures, like Faraday Cages that offer some protection against EMPs their benefits and scope of use is limited. The only assurance is absolute avoidance. How we are going to manage that is anybody’s guess.

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2006

11/9

Uncategorized

Whizz. Bang.

by | Print
{mosimage}

Fungus talks about the fearsome EMP.

Location: Hawaii. Time: Sometime in July 1958. One evening 100 burglar alarms suddenly sounded and 300 street lights suddenly blinked out for no apparent reason. All over the region, phones, radios, and televisions went dead without warning.

The cause, it turned out, was 800 miles due west and 250 miles up in the air: A 1.4 megaton nuclear weapon had been detonated some 1.32 million feet above tiny Johnston Island in the Pacific. It was a planned test, but what the U.S. military hadn’t anticipated was high-energy electrons subsequently bombarding a large swath of the Earth’s surface, crippling thousands of electrical circuits. Oops. (The same electrons also knocked out one-third of the satellites in low Earth orbit at the time, including Telstar, the very first operational communications satellite.) That test is when weapons engineers first realized that nukes were not just good for blowing up and melting stuff. They could also knock out electronics far in the distance.

Welcome to the world of EMPs.

Many of us may have been introduced to Electro-Magnetic Pulses through the 1999 cult-classic, The Matrix where they are the only weapons the rebels have against the Sentinels. EMPs are also depicted in Ocean’s 11 and the television series Dark Angel. But EMPs are neither as benign or romantic as they are made out to be on the silver screen.

The worst of the pulse lasts for only a second, but any unprotected electrical equipment — and anything connected to electrical cables, which act as giant lightning rods or antennas — will be affected by the pulse. Fluorescent lights and television sets will glow eerily bright, despite being turned off. The aroma of ozone mixed with smoldering plastic will seep from outlet covers as electric wires arc and telephone lines melt. Your Palm Pilot and MP3 player will feel warm to the touch, their batteries overloaded. Your computer, and every bit of data on it, will be toast. And then you will notice that the world sounds different too. The background music of civilization, the whirl of internal-combustion engines, will have stopped. Save a few diesels, engines will never start again. You, however, will remain unharmed, as you find yourself thrust backward 200 years, to a time when electricity meant a lightning bolt fracturing the night sky. Older, vacuum tube (valve) based equipment is much less vulnerable to EMP; Soviet cold war era military aircraft often had avionics based on vacuum tubes. There are a number of websites that explore methods for protecting equipment in the home or business from the effects of an EMP attack.

It is important to note that many nuclear detonations have taken place using bombs dropped by aircraft. The aircraft that delivered the atomic weapons at Hiroshima and Nagasaki did not fall out of the sky due to damage to their electrical or electronic systems. This is simply because electrons (ejected from the air by gamma rays) are stopped quickly in normal (dense) air for bursts below 10 km, so they don’t get a chance to be significantly deflected by the Earth’s magnetic field (the deflection causes the powerful EMP seen in high altitude bursts), but it does point out the limited use of smaller burst altitudes for widespread EMP.

An electromagnetic bomb or E-bomb is a weapon designed to disable electronics on a wide scale with an electromagnetic pulse. The electromagnetic radiation from an explosion (especially nuclear explosions) or an intensely fluctuating magnetic field is caused by Compton-recoil electrons and photoelectrons from photons scattered in the materials of the electronic or explosive device in a surrounding medium. The resulting electric and magnetic fields may couple with electrical/electronic systems to produce damaging current and voltage surges. This produces immense heat that simply fries the circuitry inside and destroys them. As such, while not being directly responsible for the loss of lives, these weapons are capable of disabling electronic systems on which industrialized nations are highly dependent. The effects are usually not noticeable beyond the blast radius unless the device is nuclear or specifically designed to produce an electromagnetic shockwave.

The theory behind the E-bomb was proposed in 1925 by physicist Arthur H. Compton–not to build weapons, but to study atoms. Compton demonstrated that firing a stream of highly energetic photons into atoms that have a low atomic number causes them to eject a stream of electrons. Physics students know this phenomenon as the Compton Effect. It became a key tool in unlocking the secrets of the atom.

Ironically, this nuclear research led to an unexpected demonstration of the power of the Compton Effect, and spawned a new type of weapon. In 1958, nuclear weapons designers ignited hydrogen bombs high over the Pacific Ocean. The detonations created bursts of gamma rays that, upon striking the oxygen and nitrogen in the atmosphere, released a tsunami of electrons that spread for hundreds of miles. Street lights were blown out in Hawaii, as previously mentioned, and radio navigation was disrupted for 18 hours, as far away as Australia. The United States set out to learn how to "harden" electronics against this electromagnetic pulse (EMP) and develop EMP weapons.

America has remained at the forefront of EMP weapons development. Although much of this work is classified, it’s believed that current efforts are based on using high-temperature superconductors to create intense magnetic fields. What worries terrorism experts is an idea the United States studied but discarded–the Flux Compression Generator (FCG)

An FCG is an astoundingly simple weapon. It consists of an explosives-packed tube placed inside a slightly larger copper coil. The instant before the chemical explosive is detonated, the coil is energized by a bank of capacitors, creating a magnetic field. The explosive charge detonates from the rear forward. As the tube flares outward it touches the edge of the coil, thereby creating a moving short circuit. The propagating short has the effect of compressing the magnetic field while reducing the inductance of the stator (coil). The result is that FCGs will produce a ramping current pulse, which breaks before the final disintegration of the device. Published results suggest ramp times of tens of hundreds of microseconds and peak currents of tens of millions of amps. The pulse that emerges makes a lightning bolt seem like a flashbulb by comparison.

The Indian military has studied FCG devices in detail because it fears that Pakistan, with which it has ongoing conflicts, might use E-bombs against the city of Bangalore, a sort of Indian Silicon Valley. An Indian Institute for Defense Studies and Analysis study of E-bombs points to two problems that have been largely overlooked by the West. The first is that very-high-frequency pulses, in the microwave range, can worm their way around vents in Faraday Cages. The second concern is known as the "late-time EMP effect," and may be the most worrisome aspect of FCG devices. It occurs in the 15 minutes after detonation. During this period, the EMP that surged through electrical systems creates localized magnetic fields. When these magnetic fields collapse, they cause electric surges to travel through the power and telecommunication infrastructure. This string-of-firecrackers effect means that terrorists would not have to drop their homemade E-bombs directly on the targets they wish to destroy. Heavily guarded sites, such as telephone switching centers and electronic funds-transfer exchanges, could be attacked through their electric and telecommunication connections.

EMPs may evoke awe and speculation. But to the world in the 21st century the over-riding emotion accompanying EMPs, and more specifically E-Bombs, is fear: Fear that the world could be set back 300 years to when electricity was not even a source of energy; Fear that the information on which this world runs could be obliterated at the whim of sufficiently dedicated madman. While there are some measures, like Faraday Cages that offer some protection against EMPs their benefits and scope of use is limited. The only assurance is absolute avoidance. How we are going to manage that is anybody’s guess.

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