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Electromagnetic Theory JULY 2008, Electrical and Electronic Engineering Department

Monday, October 13, 2008

EMP-Bomb Effects

There is a range of possible attack scenarios. Low-level electromagnetic pulses would electronics systems to be temporarily jam. More intense pulses would corrupt important computer data. Lastly, very powerful bursts would completely fry electric and electronic equipment. This situation would only affect within its lethal footprint.

There are two ways E-bomb will couple energy into targets: Frontdoor and backdoor coupling. The first will couple via antennas on mobile or wireless devices. The second way, it will not only couple via network cables, mains power wiring and telephone wiring. It will enter via cooling grilles and air gaps in computer or other electronic equipment chassis, too. This electrical damage effects occur to semiconductor components once the energy is coupled into an electronic device or computer.

Here are stated devices that are susceptible to EMP damage in decreasing vulnerability:

1. Integrated circuits (ICs), CPUs, silicon chips.
2. Transistors.
3. Vacuum tubes (also known as thermionic valves).
4. Inductors, electric motors.

In comparison between transistor technology and old vacuum equipment: The former is likely to fail, but the latter will survive. The failure probability of transistor technology due to E-bomb however, varies between the types, in specific its sensitivity to electromagnetism. Power surge would happen easier to FETs, especially MOSFETs than bipolar ICs and transistors which are much less sensitive than them.

Several ways could be applied to protect sensitive electronics equipments. Faraday cage is a commonly known solution, but only with some makeshift. A cage would be rendered useless if any conductors passed through, such as power cords or antennas. Else, optical fibres could be used as a replacement of copper information cabling infrastructure. However it is not done widely due to bureaucracies of the government and corporate variety. Adopting an electromagnetic hardening standard for industrial and commercial electronic and computer equipment would also have a huge impact - with the highly desirable collateral effect of reducing the electromagnetic interference emitted by such equipment.

Talking about modern warfare, a number of important combat missions could be accomplished in various levels of attack without causing many direct casualties by applying an effective E-bomb. It could neutralize electronic-dependent weapon and machinery, which include:

· vehicle control systems
· targeting systems, on the ground and on missiles and bombs
· communications systems
· navigation systems
· long and short-range sensor systems

The United States’ army is the leading edge of modern warfare. Recently in this decade the U.S. military has added sophisticated electronics to the full range of its arsenal. Ironically, EMP attack could be a cruel nightmare. The electronic technology in use is dependent on consumer-grade semiconductor devices. They are highly sensitive to any power surge. Thus it could affect U.S forces operations significantly due to its high vulnerability. 'The one thing that makes me lose sleep is an E-bomb, an EMP', as commented by US Air Force strategist Col Gail Wojtowicz at a Pentagon briefing.

In any country, a pervasive EMP assault would downgrade a military's ability to put itself in order. Only functioning non-electric weapons (like machine guns) would be available to ground troops, but they would not have usable electronic equipment to plan an attack or locate the enemy. Therefore, an EMP attack effectively reduces any military unit into a guerilla-type army.
EMP weapons could be especially useful in some cases, such as in Iraq. Its pulse might effectively neutralize underground bunkers. Due to the physical condition, most Iraq's underground bunkers are unreachable with conventional bombs and missiles. But using a nuclear blast would cost a shocking charge on surrounding areas, though it could effectively destroy loads of bunkers. An electromagnetic pulse could penetrate the ground, disabling the bunker's lights, ventilation systems, communication – most crucial, electric doors. As result, the bunker would be completely uninhabitable.

EMP technology draws attention because it is potentially non-fatal, but is still vastly destructive. An E-bomb attack would leave buildings standing and spare lives, but it could destroy a considerable military. These weapons are not directly responsible for the loss of lives, but if an EMP knocked out a hospital's electricity, for example, any patient on life support would die immediately.

In the end, the most sweeping effect of an e-bomb could be psychological. A full-scale EMP attack in a developed country would immediately bring modern life to halt. Plenty of survivors would be alive. But a very different world they would experience. An effectively large scale E-bomb or EMP assault may topple a country to the pre-electronic era.


Now we take a closer look on how a basic Electromagnetic Pulse (EMP) bomb works. Even though there are many theories on how an EMP bomb works, the basic idea is still the same which involving the force of electromagnetic to disrupt the intended target.

Popular Mechanics in late September 2001 published an article that outlines the possibility of EMP bomb to be constructed using inexpensive materials and also a basic engineering knowledge.

The idea focused on Flux Compression Generator Bombs (FCGs), which date back to the 1950s and this conceptual bomb design come from Carlo Kopp, an Australian freelance defense analyst.

Figure 1: Basic FCGs configuration

As can see from the figure above, FCGs consist of a metal cylinder (called the armature), which is surrounded by a coil of wire (the stator winding). The armature cylinder is filled with high explosive, and a sturdy jacket surrounds the entire device. The stator winding and the armature cylinder are separated by empty space. The bomb also has a power source, such as a bank of capacitors, which can be connected to the stator.

Figure 2: The Sequence when the bomb goes off

1. When a switch connected the capacitor to the stator is turned on, an electrical current will be passes along the wires which in turns will generates an intense magnetic field.

2. Meanwhile, a fuse mechanism ignites the explosive material and the explosion will travels as a wave through the middle of the armature cylinder.

3. As the explosion makes its way through the cylinder, the top of the cylinder will come in contact with the stator winding and creates a short circuit that cutting the stator off from its power supply.

4. The moving short circuit compresses the magnetic field and generating an intense electromagnetic burst at the end of the bomb.

Another way to view this phenomenon is imagines that the explosion as a force that pushing a piston rod that helps to deliver the intense electromagnetic burst along the cylinder.

The explosion is needed to move the intense electromagnetic fast enough without giving the electromagnetic burst enough time to be dissipate and also in the process, will destroy the device from reproduce by another person.

Figure 3: Revise version of EMP bomb

The figure above shows that the basic idea of FCGs been put into a more completed form. As you can see, it has an addition of components to deliver the intense magnetic burst in wider radius compared if the single unit of FCGs had been detonated. This unit works as drop off bomb so that the intense electromagnetic burst can be delivered vertical and covered a wider radius. It also can be delivered horizontal and it will need to use a propulsion system to drive the system such as a rocket.

Sunday, October 12, 2008

Theory of EMP-Bomb

EMP-Bomb can be easily understood like this. All of us know that microwave oven is functioning using the theory of electromagnetic wave that had the same frequency as water. When the frequency of microwave oven is same as the frequency of water in the food, the molecules of water start to vibrate. The vibrating molecules will produce heat that will cook the food. Then, how about we substitute the food with Integrated Circuit (IC) into the microwave oven? There are no water molecules in IC but how can it burnt? The answer is easy; it is due to Electromagnetic Field (EMF) produce by the microwave oven that induced the current in IC, make the current very high, and everything burnt because of high current and voltage.

Nuclear type is much more dangerous than non-nuclear type because of its ability to harm human life directly. When nuclear bomb is detonated, a stream of highly accelerating photon is produced. The stream of photon will strike the hydrogen and oxygen atom in atmosphere, thus highly accelerating electron are produced. The accelerating electron will produced what we call Electromagnetic Pulse (EMP). The EMP will move away from the detonated place, as far as 1000 miles. The EMP will act as a big wave noise and disturb other wave such as radio wave, television wave and satellite wave thus any transmitted information cannot be received. Moreover, when the EMP strikes any active electronic components, it will cause EMF that surrounded the components. The EMF will cause a high voltage across the components, so the components will burn. These effects are worse to ICs as there had very low cut-off voltage.

For the non-nuclear type, it is only affected the electronic components without any harm to human life directly. The principle is simple to imagine; a bomb that full of compressed EMF is detonated, thus the EMF will separated and strike the electronic components within it moving radius. The theory how to perform this mechanism is explained in the methodology part. This type of nuclear can be categorized into 3 types; Ground Detonation, Mid-Air Detonation, and High-Altitude Detonation. For Ground Detonation, the radius of EMP explosion is small compare to the other two types. However, this type is the easiest one to control the explosion radius. For the Mid-Air Detonation, the radius of EMP explosion is larger than Ground Detonation but smaller that High-Altitude Detonation. The explosion radius can also be controlled like Ground Detonation. For High-Altitude Detonation, the radius of EMP explosion is the largest compare to the other two types. The explosion radius is hard to control. So, it is always the best choice for scientist and engineers to choose the Mid-Air Detonation types


In 1925, the theory behind the E-bomb was proposed by physicist, Arthur H. Compton. He was not trying to build the weapon but just studying atoms. Compton was able to demonstrate that firing a stream of highly energetic photons into atoms that have a low atomic number causes them to eject a stream of electrons. His nuclear research led to an unexpected demonstration of the power and creation of a new type of weapon

The existence of this electromagnetic pulse has been known since the 1940’s.It was when the nuclear weapons were being developed and tested.However, the effects of an EMP bomb were not fully known until 1962 because of lack of data. At that time, the United States was conducting a series of high-altitude atmospheric tests named "Fishbowl” .The nuclear weapons designers ignited hydrogen bombs over the Pacific Ocean. The detonations created bursts of gamma rays. The gamma rays strike the oxygen and nitrogen in the atmosphere, released electrons that spread for hundreds of miles. As a result, street lights in Hawaii were blown out and radio navigation was disrupted for 18 hours, as far away as Australia. Then, the United States start to learn how to "harden" electronics against this electromagnetic pulse (EMP) and develop EMP weapons.

In 1963, the Atmospheric Test Ban Treaty was signed by the United States and Soviet Union to counter the possible threat imposed by electromagnetic pulses. Unfortunately, the destructive potential of an EMP increases everyday as society becomes evermore technological.

In 1991, the U.S. Navy used experimental E-bombs for the Gulf War. These bombs used warheads that converted the energy of conventional explosives into a pulse of radio energy.

In 1998, David Schriner, a former civilian electrical engineer for the US Navy, told the Congress that he spent $US500 to buy automobile ignition coils, batteries, fuel pumps and various used hardware in his basement to build an e-bomb. In one week, he built an e-bomb that could make a running car hiccup at 15 meters by overloading its electrical component. So, the Congress agreed to give Schriner a million-dollar contract to see if he could build a truly effective e-bomb out of readily available materials. This proves that an e-bomb is a lot easier to build than a nuclear bomb, and they don't have to be delivered by very high technology missiles.

In 2000, British scientists at Matra Bae Dynamics(British Defence Firm) developed a non-explosive artillery shell serving as an E-bomb that could destroy electrical and electronic systems for miles. This E-bomb uses radio frequencies to destroy enemy’s electronics.