Electromagnetic Pulse

EMP Meaning

An electromagnetic pulse (EMP) is a short rupture of electromagnetic energy. It is also known as a transient electromagnetic disturbance. This pulse can be originated naturally or man-made. It can occur as a radiated electric or magnetic field or a conducted electric current depending upon the source. Electromagnetic pulse involvement basically damages electronic equipment. At a higher energy level, EMP has a powerful event that is a lightning strike that damages the physical objects, such as buildings and many more lives on the earth. Its short duration means it gets spread over a large range of frequencies. 


What Is A Pulse In Physics

Pulse can be stated as a single disturbance that moves through a medium from one point to another. The medium can be a vacuum, matter, or any other. 

If a person is holding a rope tightly at one end and the pulse is generated in a rope then it is said that the pulse is approaching the fixed end.

On the other hand, if the rope is tied to a stick that is able to move up and down then the pulse generated is said to be approaching the free end.


Types of Electromagnetic Pulse 

An electromagnetic pulse can be natural,  man-made, or weapons effects they are listed below.

In the case of man-made EMP thermonuclear device being explored in the upper atmosphere, the resulting explosion emits gamma rays. These gamma-ray particles are rapidly accelerating and become charged as they fall back to the earth.

These charged particles disrupt the electronic systems by sending the unregulated amount of voltage through the circuits. 

This example is commonly known as High-Altitude Electromagnetic Pulse (HEMP).

Man-made electromagnetic pulses occur due to the following reasons,

  1. Switching off electrical circuitry when it is repeated continuously.

  2. Rush in power lines.

  3. The gasoline engine ignition system can create a train of pulses as the spark plugs are energized.

Natural electromagnetic pulses ignition occurs due to 

  1. Electrostatic discharge, as a result of two charged objects coming into close or even contact.

  2. Lightning electromagnetic pulse the discharge in this is an initial huge current flow.

  3. Meteoric electromagnetic pulse.

  4. Coronal mass ejection is the release of plasma and magnetic fields from the solar corona.

Military electromagnetic pulses include,

  1. Nuclear electromagnetic pulse results from nuclear explosions. It is used in military purposes during wars to make bombs and other kinds of stuff.

  2. A non-nuclear electromagnetic pulse is generated due to weapons and not due to nuclear technology. 


Electromagnetic Pulse (Emp) Range 

A pulse of electromagnetic energy starts from a very low range to a high range this depends on the source.

The range can be defined as emp, which is also referred to as DC to daylight, excluding the higher frequencies.


Production of Electromagnetic Pulse

There are three categories of electrical pulse charges listed as E1, E2, and E3. An E1 pulse charge strikes first and it is the exclusive form of electrical shock which occurs in a fraction of seconds. 

  1. An E1 pulse will destroy consumer electronics, and un-hardened EMP equipment if not properly shielded. Any electronic devices connected to an antenna that receives an electronic signal cannot be shielded against an E1 pulse, regardless of any EMP shielding efforts.

  2. The second type of charge is an E2 pulse, which has the same effect as by natural lightning. It produces greater damage to electronic infrastructure but it is easy to protect against it. Most electrical components have built-in or added protection against lightning strikes, which gives damage to connected systems. An example of this is a surge protector, which is commonly connected to home and office electronics to prevent electrical surge damage from a lightning strike. An E2 pulse strikes a fraction of a second after an E1 pulse. E1 pulses normal protection measures as such home surge protectors, essentially leading the way for E2 pulses to greatly further damaged systems.

  3. The next charged particle is called an E3 which is a longer duration pulse lasting for around one minute. An E3 pulse is an electromagnetically distorted wave, propagated in the atmosphere. This pulse can closely resemble the effect of a geomagnetic storm. E3 pulses resonate along with a greater distance and have a greater damaging effect against power lines, electrical cables, and transformers. E3 pulses literally go the distance following E1 and E2 pulses, knocking out remaining connected electronic infrastructure.

The sequential timing and coupling of these three pulses one after another produces the damaging effect of an EMP. The coupling effect of all three pulses is known as an EMP.

FAQ (Frequently Asked Questions)

1. What is the protection against electromagnetic pulse?

There are many ways to protect against electromagnetic pulse attack. One of them is electrical shielding. In this protection technique, if an electrical cable is grounded with a shield, the electromagnetic pulse would not be able to penetrate the shield. The current caught in the shields will be released into the ground as a harmless by product. By this method, we can protect the wires and cables in the electronic circuit from getting destroyed. This method is only effective in protecting the cables and wires, not the smaller electronics that are connected to the circuits directly.


2. What are the waveforms of the electromagnetic pulse?

The waveforms describe how immediately the amplitude changes with the time. The waveform we get is very complicated, so a simplified waveform model is used to understand.

According to the waveform, the pulses increase rapidly, giving us a sharp edge it reaches a maximum value after that the pulse decays slowly. The classical model is a double exponential curve because it increases slowly, and decreases rapidly.

The waves we get can be a rectangular wave, damped sine wave, or double exponential wave.