EMP(Electro-magnetic Pulse)

By SK. TARIK AHMED

INTRODUCTION

I think most of us familiar with the name of EMP by the sake of the game NFS Hot Pursuit. We saw there cops are busted the street racer’s cars using EMP. But EMP

is quite broadly beside this.

An electromagnetic pulse (sometimes abbreviated EMP) is a burst of electromagnetic radiation that results from an explosion (usually from the detonation of a nuclear weapon) and/or a suddenly fluctuating magnetic field. The resulting rapidly changing electric fields or magnetic fields may couple with electrical/electronic systems to produce damaging current and voltage surges.It may generated by Natural process- Geomagnetic solar storm, or by Artificially ; i.e. Nuclear EMP, Non Nuclear EMP.

WHAT IS EMP?

GENARATION OF EMP• We can generate EMP by- By nuclear(NEMP) By non nuclear process(NNEMP).

• NEMP• In military terminology, a nuclear bomb detonated hundreds of kilometers

above the Earth's surface is known as a high-altitude electromagnetic pulse (HEMP) device. Effects of a HEMP device depend on a very large number of factors, including the altitude of the detonation, energy yield, gamma ray output, interactions with the Earth's magnetic field, and electromagnetic shielding of targets. When nuclear bomb detonated three types of EMP produced-

1. E 12. E 23. E 3

EMP 1 The E1 pulse is the very fast component of nuclear EMP. The E1 component is produced

when gamma radiation from the nuclear detonation knocks electrons out of the atoms in the upper atmosphere. The typical gamma rays given off by the weapon have an energy of about 2 MEV (calculated by Conrad Longmire). By Compton effect The gamma rays transfer about half of their energy to the electrons, so these initial electrons have an energy of about 1 MEV. This causes the electrons to begin to travel in a generally downward direction at about 94 percent of the speed of light. Relativistic effects cause the mass of these high energy electrons to increase to about 3 times their normal rest mass. If there were no geomagnetic field and no additional atoms in the lower atmosphere for additional collisions, the electrons would continue to travel downward with an average current density in the stratosphere of about 48 amperes per square metre. Because of the downward tilt of the Earth's magnetic field at high latitudes, the area of peak field strength is a U-shaped region to the equatorial side of the nuclear detonation. The Earth's magnetic field quickly deflects the electrons at right angles to the geomagnetic field. These initial electrons are stopped by collisions with other air molecules at a average distance of about 170 metres, and generates secondary electrons. There are a number of secondary collisions which cause the subsequent electrons to lose energy before they reach ground level. The electrons generated by these subsequent collisions have such reduced energy that they do not contribute significantly to the E1 pulse. These 2 MEV gamma rays will normally produce an E1 pulse near ground level at moderately high latitudes that peaks at about 50,000 volts per metre. This is a peak power density of 6.6 megawatts per square metre.

Effects of E1 Pulse

E1 Pulse travels at 90% of the speed of light

Peaks after 5 - 10 nanoseconds, over in 1 microsecond

Normal circuit breakers do not work this fast

Amplitude up to 50,000 volts/meter

Circuit boards are 1 million times more sensitive than vacuum tubes

Will cause integrated circuits connected to cables to overheat and give false readings, be damaged or destroyed

EMP 2

The E2 component is generated by scattered gamma rays and inelastic gammas produced by weapon neutrons. This E2 component is an "intermediate time" pulse that, by the IEC definition, lasts from about 1 microsecond to 1 second after the beginning of the electromagnetic pulse. The E2 component of the pulse has many similarities to the electromagnetic pulses produced by lightning, although the electromagnetic pulse induced by a nearby lightning strike may be considerably larger than the E2 component of a nuclear EMP. Because of the similarities to lightning-caused pulses and the widespread use of lightning protection technology, the E2 pulse is generally considered to be the easiest to protect against.

According to the United States EMP Commission, the main potential problem with the E2 component is the fact that it immediately follows the E1 component, which may have damaged the devices that would normally protect against E2.

Effects of E2 Pulse E2 Pulse is very similar to the electromagnetic pulse produced by

lightning.

Because of the widespread use of lightning protection technology, E2 probably is the least dangerous type of EMP

Effect would be similar to thousands of lighting strikes hitting power lines simultaneously

Damage from E1 Pulse immediately previously could partially degrade lightning protection

EMP3

The E3 component is very different from the other two major components of nuclear EMP. The E3 component of the pulse is a very slow pulse, lasting tens to hundreds of seconds, that is caused by the nuclear detonation heaving the Earth's magnetic field out of the way, followed by the restoration of the magnetic field to its natural place. The E3 component has similarities to a geomagnetic storm caused by a very severe solar flare. Like a geomagnetic storm, E3 can produce geomagnetically induced currents in long electrical conductors, which can then damage components such as power line transformers.

Because of the similarity between solar-induced geomagnetic storms and nuclear E3, it has become common to refer to solar-induced geomagnetic storms as "solar EMP." At ground level, however, "solar EMP" is not known to produce an E1 or E2 component.

Effects of E3 Pulse E3 Pulse lasts from tens of

seconds to several minutes Produces direct current Ground

Induced Currents (GIC) in conductors

Long distance electrical power transmission lines make excellent conductors

The longer the conductor and the lower its resistance, the easier the GIC can flow

Direct currents of hundreds to thousands of amperes will flow into transformers, potentially causing overheating and fires Transformer Damaged During

1989 Geomagnetic Storm

NNEMP Non-nuclear electromagnetic pulse (NNEMP) is an electromagnetic pulse

generated without use of nuclear weapons. There are a number of devices that can 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. 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. A vacuum tube particularly suitable for microwave conversion of high energy pulses is the vircator]

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.

The range of NNEMP weapons (non-nuclear electromagnetic bombs) is severely limited compared to nuclear EMP. This is because nearly all NNEMP devices used as weapons require chemical explosives as their initial energy source, but nuclear explosives have an energy yield on the order of one million times that of chemical explosives of similar weight.  In addition to the large difference in the energy density of the initial energy source, the electromagnetic pulse from NNEMP weapons must come from within the weapon itself, while nuclear weapons generate EMP as a secondary effect, often at great distances from the detonation.

Marx generatorThere are several ways to generates NNEMP. But one of the oldest technique is Marx generator.

Principal: A number of capacitors are charged in parallel to a given voltage, V, and then connected in series by spark gap switches, ideally producing a voltage of V multiplied by the number, n, of capacitors (or stages). Due to various practical constraints, the

output voltage is somewhat less than n×V.

Hollow tube generators• The MK-1 generator functions as follows:• A longitudinal magnetic field is produced inside a hollow metallic conductor,

by discharging a bank of capacitors into the solenoid that surrounds the cylinder. To ensure a rapid penetration of the field in the cylinder, there is a slot in the cylinder, which closes rapidly as the cylinder deforms;

• The explosive charge placed around the tube is detonated in a manner that ensures that the compression of the cylinder commences when the current through the solenoid is at its maximum;

• The convergent cylindrical shock wave unleashed by the explosion produces a rapid contraction (greater than 1 km/s) of the central cylinder, compressing the magnetic field, and creating an inductive current, as per the explanation above (the speed of contraction permits, to first approximation, the neglect of Joule losses and the consideration of the cylinder as a perfect conductor).

• The first experiments were able to attain magnetic fields of millions of gauss (hundreds of teslas, given an initial field of 30 kG (3 T which is in the free space "air" same as B/u0 = H --> 3 Vs/m^2 / 4pi10^-7 Vs/Am = 2.387x10^6 A/m so it is about 2.4 M A/m)

Elementary description of flux compression

An external magnetic field (blue lines) threads a closed ring made of a perfect conductor (with zero resistance). The nine

field lines represent the magnetic flux threading the ring.

After the ring's diameter is reduced, the magnetic flux threading the ring, represented by five field lines, is reduced by the same ratio as the area of the ring. The variation of the

magnetic flux induces a current in the ring (red arrows), which in turn creates a new magnetic field, so that the total flux in the interior of the ring is maintained (four green field lines added to the five blue lines give the original nine field

lines).

By adding together the external magnetic field and the induced field, the final configuration after compression can be

obtained; the total magnetic flux through the ring has been conserved (even though the distribution of the magnetic flux

has been modified), and a current has been created in the conductive ring.

Uses of EMP

It can destroy any electronics goods i.e. microprocessors

Several uses in Military and Defense

It can destroy missals before hitting target.

I can destroy fighter plans.

Eliminate all communication system of enemy .

This EMP Cannon Stops Cars Almost Instantly

This EMP Cannon Stops Cars Almost Instantly:

Apparently they can also be used to stop moving cars just as fast. The cannon demonstrated in the video here is still a prototype, but it definitely seems to work.

The idea is that an electromagnetic pulse would be used to disable a car's microprocessors, chips, and whatever other electronics are keeping it running. The final "cannon" system, built by Eureka Aerospace, will apparently a bit smaller and lighter than what we see in the video—it'll be suitcase-sized and about 50 pounds—and it will "stop cars in their tracks up to 656 feet (200 m) away."

Australia develops non-nuclear EMP bombs

– Australia's Defence Science and Technology Organisation has

revealed a research and development programme for non-

nuclear electromagnetic pulse (EMP) bombs, and is building at least one prototype for testing. The weapon would be used to neutralise electronics without damaging people or property.

Consequences of Power Loss

• “Should the electrical power system be lost for any substantial period of time … the consequences are likely to be catastrophic … machines will stop; transportation and communication will be severely restricted; heating, cooling and lighting will cease; food and water supplies will be interrupted; and many people may die”

2008 EMP Commission

Geomagnetic Storms March 1989 (Quebec)

480 nT/min Knocked out power to 6 million people in 92 seconds

May 1921 Up to 4,800 nT/min

Sept. 1859 (Carrington event) 2,000 to 5,000 nT/min

Nuclear EMP Tests US – Starfish Prime (1962)

1.44 Mt burst, 250 mi altitude over Johnston Island in the South Pacific

5.6 kv/m E1 pulse in Honolulu

USSR – Test 184 (1962) 300 kt burst, 180 mi altitude over Kazakhstan 1,000 to 1,300 nT/min E3 pulse Power station 300 mi distant set on fire by E3 Pulse effects and

destroyed within 10 seconds 2,500 amp current induced in overhead phone line

What Can We Do Reestablish the EMP Commission

Conduct more tests

Protect transformers and generating plants

Assure availability of replacement equipment

Increase number of frequency independent ‘islands’ in the electrical system

Expand emergency power supplies

Extend ‘black start’ capability

Shield critical SCADA and communications components