The term electromagnetic pulse (EMP) has the following meanings:
In the case of a nuclear detonation or an asteroid impact, most of the energy of the electromagnetic pulse is distributed in the frequency band between 3 Hz and 30 kHz. In Medicine, a person's pulse is the throbbing of their arteries. Frequency is a measure of the number of occurrences of a repeating event per unit Time.
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. A lightning rod (USA or lightning conductor (UK is a single component in a Lightning protection system. An antenna is a Transducer designed to transmit or Receive electromagnetic waves In other words antennas convert electromagnetic waves into 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. This article is about the electronic device not an evacuated pipe used for experiments in Free-fall. The Union of Soviet Socialist Republics (USSR was a constitutionally Socialist state that existed in Eurasia from 1922 to 1991 Cold War is the state of conflict tension and competition that existed between the United States and the Soviet Union (USSR and their respective allies from the There are a number of websites that explore methods for protecting equipment in the home or business from the effects of an EMP attack.
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. The Japanese city of ( is the capital of Hiroshima Prefecture, and the largest city in the Chūgoku region of western Honshū, the largest of Japan 's ( is the Capital and the largest city of Nagasaki Prefecture in Japan. This is simply because electrons (ejected from the air by gamma rays) are stopped quickly in normal air for bursts below 10 km, so they do not 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. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J Earth 's magnetic field (and the surface magnetic field) is approximately a Magnetic dipole, with one pole near the North pole (see
If the B-29 planes had been within the intense nuclear radiation zone when the bombs exploded over Hiroshima and Nagasaki, then they would have suffered effects from the charge separation (radial) EMP. Photoinduced charge separation is the process of an Electron in an Atom being excited to a higher energy level and then leaving the atom to a nearby Electron But this only occurs within the severe blast radius for detonations below about 10 km altitude. EMP disruptions were suffered aboard KC-135 photographic aircraft flying 300 km from the 410 kt Bluegill and 410 kt Kingfish detonations (48 and 95 km burst altitude, respectively) in 1962 , but the vital aircraft electronics then were far less sophisticated than today and did not crash the aircraft. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout Operation Dominic was a series of 105 Nuclear test explosions conducted in 1962 and 1963 by the United States. Operation Dominic was a series of 105 Nuclear test explosions conducted in 1962 and 1963 by the United States.
Several major factors control the effectiveness of an EMP weapon. These are:
Beyond a certain altitude a nuclear weapon will not produce any EMP, as the gamma rays will have had sufficient distance to disperse. In deep space or on worlds with no magnetic field (the moon or Mars for example) there will be little or no EMP. This has implications for certain kinds of nuclear rocket engines. See Project Orion. Project Orion was the first engineering design study of a Spacecraft powered by Nuclear pulse propulsion, an idea first proposed by Stanisław Ulam
Thus, for equipment to be affected, the weapon needs to be above the visual horizon. The horizon ( Ancient Greek ὁ ὁρίζων, /ho horídzôn/ from ὁρίζειν, "to limit" is the apparent line that separates Because of the nature of the pulse as a large, long, high powered, noisy spike, it is doubtful that there would be much protection if the explosion were seen in the sky just below the tops of hills or mountains. In electrical engineering spikes are fast short duration electrical transients in voltage ( voltage spikes) current ( current spike) or transferred energy
The altitude indicated above is greater than that of the International Space Station and many low Earth orbit satellites. A Low Earth Orbit (LEO is generally defined as an Orbit within the locus extending from the Earth’s surface up to an altitude of 2000 km Large weapons could have a dramatic impact on satellite operations and communications; smaller weapons have less such potential. This article is about artificial satellites For natural satellites also known as moons see Natural satellite.
Typical nuclear weapon yields quoted in such scenarios are in the range of 20 megatons. The explosive yield of a nuclear weapon is the amount of Energy, called the Yield, discharged when a Nuclear weapon is detonated expressed usually This is roughly 1,000 times the sizes of the weapons the United States used in Japan at Hiroshima and Nagasaki. The United States of America —commonly referred to as the For a topic outline on this subject see List of basic Japan topics. The Japanese city of ( is the capital of Hiroshima Prefecture, and the largest city in the Chūgoku region of western Honshū, the largest of Japan 's ( is the Capital and the largest city of Nagasaki Prefecture in Japan.
The major energy in an EMP is electromagnetic, and radiates out from the point of detonation in a sphere. EMP is electromagnetic radiation. Electromagnetic radiation takes the form of self-propagating Waves in a Vacuum or in Matter. The intensity of these fields decreases in proportion to the circumference and distance from explosion. The actual amount of EMP energy deposited per unit area is entirely different, and that falls off as the inverse-square of distance.
|Radius in Miles||Circumference||Relative Strength|
|10||62. 83||100% or 1|
|20||125. 66||50% or 1/2|
|30||188. 50||33. 3% or 1/3|
|40||251. 32||25% or 1/4|
|The range of deposition of gamma rays in the atmosphere is assumed to be 10 miles, which is appropriate for a 1 megaton burst at an altitude of about 10 miles. The size of the perimeter of this circle grows in proportion to the radius of the circle, and so the electric field strength weakens as the circle grows. By simple mathematics the electric field strength does not fall as the inverse square law, but is instead a simple inverse linear relationship.|
The range of deposition of gamma rays would be smaller for a surface burst because of the greater air density, which shields the initial gamma rays that cause the EMP. Conversely, for a burst at greater altitudes, the range of the deposition would be far greater than 10 miles, because the gamma rays could travel much further in the low density air before being stopped. The actual energy deposited per unit area, if emitted from an isotropic point source, is always governed by the inverse-square law. A point source is a single identifiable localized source of something
But the damaging effect of EMP is determined largely by the peak electric field (measured in volts/metre), which falls only inversely with distance. The amount of EMP energy passing through a unit of area is proportional to the square of the field strength. In Physics, the field strength of a field is the magnitude of its vector value Within the range of gamma ray deposition, these simple laws no longer hold as the air is ionised and there are other EMP effects such as a radial (non-radiated) electric field due to the separation of Compton electrons from air molecules, and other complex phenomena. Ionization is the physical process of converting an Atom or Molecule into an Ion by adding or removing charged particles such as Electrons so its energy = 1/d^2
Non-nuclear electromagnetic pulse (NNEMP) is an electromagnetic pulse generated without use of nuclear weapons. There are a number of devices to achieve this objective, ranging from a large low-inductance capacitor bank discharged into a single-loop antenna or a microwave generator to an explosively pumped flux compression generator. A capacitor is a passive electrical component that can store Energy in the Electric field between a pair of conductors An explosively pumped flux compression generator (EPFCG is a device used to generate a high-power Electromagnetic pulse by compressing magnetic flux using High explosive To achieve the frequency characteristics of the pulse needed for optimal coupling into the target, wave-shaping circuits and/or microwave generators are added between the pulse source and the antenna. In Electronics and Telecommunication, coupling is the desirable or undesirable Transfer of energy from one medium, such as a metallic wire or An antenna is a Transducer designed to transmit or Receive electromagnetic waves In other words antennas convert electromagnetic waves into A vacuum tube particularly suitable for microwave conversion of high energy pulses is the vircator. A vircator (VIRtual CAthode OscillatOR is a Microwave generator that is capable of generating brief pulses of tunable narrow band microwaves at very high power levels
NNEMP generators can be carried as a payload of bombs and cruise missiles, allowing construction of electromagnetic bombs with diminished mechanical, thermal and ionizing radiation effects and without the political consequences of deploying nuclear weapons. A cruise missile is a guided Missile that carries an explosive payload and uses a lifting wing and a propulsion system usually a Jet engine, to allow An electromagnetic bomb or E-bomb is a weapon designed to disable electronics with an Electromagnetic pulse (EMP that can couple with electrical/electronic systems
NNEMP generators also include large structures built to generate EMP for testing of electronics to determine how well it survives EMP. In addition, the use of ultra-wideband radars can generate EMP in areas immediately adjacent to the radar; this phenomenon is only partly understood.
Typical modern scenarios seen in news accounts speculate about the use of nuclear weapons by rogue states or terrorists in an attack. Terrorism is the systematic use of terror especially as a means of coercion These typically involve weapons similar to those used over Hiroshima and Nagasaki. Aerial detonation would require the use of aircraft, or surface launched missiles of limited range (typically a range 100 to 300 miles). A surface to air missile ( SAM) or ground-to-air missile ( GTAM) is a Missile designed to be launched from the ground to destroy Aircraft The scenarios have the detonations typically occurring within the earth's atmosphere, and likely relatively close to the ground (within a dozen or so miles).
This would limit the EMP effect because the altitude of the explosion would be much lower than that needed to be above the visual horizon of the entire United States. Also, the power of the weapons would typically be hundreds if not thousands of times smaller than optimum, and thus the effect would be significantly smaller than that of a larger weapon.
However, the EMP at a fixed distance from a nuclear weapon does not depend directly on the yield but at most only increases as the square root of the yield (see illustration above). This means that although a 10 kt weapon has only 0. 7% of the total energy release of the 1. 4 Mt Starfish Prime test, the EMP will be at least 8% as powerful. Starfish Prime was a high-altitude nuclear test conducted by the United States of America on July 9, 1962, a joint effort of the Since the EMP depends on the prompt gamma ray output, which was only 0. 1% of yield in Starfish Prime but can be 0. Starfish Prime was a high-altitude nuclear test conducted by the United States of America on July 9, 1962, a joint effort of the 5% of yield in pure fission weapons of low yield, a 10 kt bomb can easily be 5 x 8% = 40% as powerful as the 1. 4 Mt Starfish Prime at producing EMP . Starfish Prime was a high-altitude nuclear test conducted by the United States of America on July 9, 1962, a joint effort of the
The total prompt gamma ray energy in a fission explosion is 3. 5% of the yield, but in a 10 kt detonation the high 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 kilotons. In the thermonuclear Starfish Prime the fission yield was less than 100% to begin with, and then the thicker outer casing absorbed about 95% of the prompt gamma rays from the pusher around the fusion stage. In Physics and Nuclear chemistry, nuclear fusion is the process by which multiple- like charged atomic nuclei join together to form a heavier nucleus Starfish Prime was a high-altitude nuclear test conducted by the United States of America on July 9, 1962, a joint effort of the Thermonuclear weapons are also less efficient at producing EMP because the first stage can pre-ionise the air , which becomes conductive and hence rapidly shorts out the electron Compton currents generated by the final, larger yield thermonuclear stage. Nuclear weapon designs are physical chemical and engineering arrangements that cause the physics package of a nuclear weapon to detonate The Compton shift formula Klein-Nishina formulaCompton used a combination of three fundamental formulas representing the various aspects of classical and modern physics combining Hence, small pure fission weapons with thin cases are far more efficient at causing EMP than most megaton bombs.
A terrorist EMP attack might profoundly affect any major city; however, because of the high cost of real estate and traffic issues, many major businesses have relocated valuable assets outside of major urban areas, and have taken other measures to protect themselves. Therefore, the long-term economic and technological impact of such an event might not be as grave as previously imagined, depending on the nature of the original attack.
A common scenario is detonation of a device over the middle of the U. S. using long-range missiles available only to major military powers. An offshore detonation at high altitude, by contrast, would present less technical difficulty and would disrupt both an entire coast and regions hundreds of miles inland (e. g. 120 mile altitude, 1000 mile EMP radius). The term electromagnetic pulse ( EMP) has the following meanings Electromagnetic radiation from an Explosion (especially a Nuclear Moreover, a high altitude burst could be positioned over international waters by means of a missile of low accuracy, launched from a ship, also in international waters. North Korea, Iran, and Pakistan (for example) have Scud-derived missiles of more than adequate capability. The Rodong-1 (spelled Nodong-1 in South Korea is a single stage, mobile liquid propellant medium range Ballistic missile developed by North The Shahab-2 ( Persian: شهاب-۲ meaning "Meteor-2" is the successor to the Iranian Shahab-1 missile Ghauri (غوری is a Medium-range ballistic missile developed by Kahuta Research Laboratories (KRL of Pakistan. Scud is a series of Tactical ballistic missiles developed by the Soviet Union during the Cold War and exported widely to other countries