EM BOMB

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EM BOMB

• The Next Generation Weapon ???

• PARTH MEHTA
• 07EC441

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Modern World is a Battlefront

• Present era can be classified as an era of
  Technology, era of computers or age of
  industries.
• But in history it will be surely classified as an
  era of WAR and Terrorism
• In modern world its impossible for any country to
  remain aloof from wars however peaceful and non
  violent it may claim to be.
• Be it for progress or on ethical grounds, be it
  invasive or defensive but war is inevitable.
• And if a nation has to be indulged in war the
  only necessity is to win or at least be able to
  protect itself from invasion.

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• The efficient execution of a war campaign against
  a modern industrial or post-industrial opponent
  will require the use of specialized tools
  designed to destroy or disrupt information
  systems, Power Supply Systems And Major
  Industries of opponents.
• In case of a War situation between a highly
  advanced nation and a technologically backward
  nation it becomes all the more necessary and
  unavoidable to use such means which are
  technologically and economically feasible yet
  highly devastating.
• Today the technical and intellectual progress of
  mankind has presented us with many such weapons
  one of the most important of which is
• EM BOMB

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WHAT IS AN EM BOMB???

• 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 to produce damaging
  current and voltage surges by electromagnetic
  induction.

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HISTORY

• 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. 
• The resulting electromagnetic pulse induced
  intense electrical currents in conductive
  materials over a wide area.

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• The electromagnetic pulse was first observed
  during high-altitude nuclear weapon detonations.
• 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 and radio
  navigation was disrupted for 18 hours, as far
  away as Australia.

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• The US Army Corps of Engineers issued a publicly
  available pamphlet in the late 1990s that
  discusses in detail how to harden a facility
  against "HEMP - high frequency electromagnetic
  pulse.
• According to some reports, the U.S. Navy used
  experimental E-bombs during the 1991 Gulf War.
• These bombs utilized warheads that converted the
  energy of conventional explosives into a pulse of
  radio energy.
• It describes how water pipes, antennas,
  electrical lines, and windows allow EMP to enter
  a building.

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• The Soviet Union conducted significant research
  into producing nuclear weapons specially designed
  for upper atmospheric detonations, a decision
  that was later followed by the United States and
  the United Kingdom.
• Though only the Soviets ultimately produced any
  significant quantity of such warheads.
• But the most of them were disarmed following the
  Reagan-era arms talks.
• CBS News also reported that the U.S. dropped an
  E-bomb on Iraqi TV during the 2003 invasion of
  Iraq, though this has not been confirmed.
• Its Doubtless that EMP-specialized nuclear weapon
  designs belong to the third generation of nuclear
  weapons

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The Basic Principle.

• The basic principle is characterized by the
  production of a very short but intense
  electromagnetic pulse, which propagates away from
  its source with ever diminishing intensity,
  governed by the theory of electromagnetism. The
  Electromagnetic Pulse is in effect an
  electromagnetic shock wave.
• Small nuclear weapons detonated at high altitudes
  can produce a strong enough signal to disrupt or
  damage electronics many miles from the locus of
  the explosion.
• During a nuclear EMP, the magnetic flux lines of
  the Earth alter the dispersion of energy so that
  it radiates very little to the North, but spreads
  out East, West, and South of the blast

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• The signal is divided into several time
  components, and can result in thousands of volts
  per meter of electromagnetic energy ranging from
  extreme negative to extreme positive polarities.
  This energy can travel long distances on power
  lines and through the air.
• This pulse of energy produces a powerful
  electromagnetic field, particularly within the
  vicinity of the weapon burst.
• The field can be sufficiently strong to produce
  short lived transient voltages of thousands of
  Volts on exposed electrical conductors, such as
  wires, or conductive tracks on printed circuit
  boards, where exposed.

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• This aspect of the EMP effect is of military
  significance, as it can result in irreversible
  damage to a wide range of electrical and
  electronic equipment, particularly computers and
  radio or radar receivers.
• Subject to the electromagnetic hardness of the
  electronic equipment, a measure of the
  equipment's resilience to this effect, and the
  intensity of the field produced by the weapon,
  the equipment can be irreversibly damaged or in
  effect electrically destroyed.
• The damage inflicted is not unlike that
  experienced through exposure to close proximity
  lightning strikes, and may require complete
  replacement of the equipment, or at least
  substantial portions thereof.

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What is inside the EM-Bomb?

• EM Bomb Basically consists of one of the
  following
• Flux Compression Generators (FCG)
• Explosive or propellant driven
  Magneto-Hydrodynamic (MHD) generators
• A range of HPM devices, the foremost of which is
  the Virtual Cathode Oscillator or Vircator.

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• The FCG was first demonstrated by Clarence Fowler
  at Los Alamos National Laboratories in the late
  fifties.
• The FCG is a device capable of producing
  electrical energies of tens of Mega Joules in
  tens to hundreds of microseconds of time, in a
  relatively compact package.
• With peak power levels of the order of Terawatts
  to tens of Terawatts, FCGs may be used directly,
  or as one shot pulse power supplies for microwave
  tubes.
• The current produced by a large FCG is between
  ten to a thousand times greater than that
  produced by a typical lightning stroke

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• The central idea behind the construction of FCGs
  is that of using a fast explosive to rapidly
  compress a magnetic field, transferring much
  energy from the explosive into the magnetic
  field.
• The initial magnetic field in the FCG prior to
  explosive initiation is produced by a start
  current supplied by an external source, such a a
  high voltage capacitor bank , a smaller FCG or an
  MHD device.
• In principle, any device capable of producing a
  pulse of electrical current of the order of tens
  of kilo Amperes to Mega Amperes will be suitable.
• A number of geometrical configurations for FCGs
  have been published
• The most commonly used arrangement is that of the
  coaxial FCG.

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Explosive and Propellant Driven MHD Generators

• The fundamental principle behind the design of
  MHD devices is that a conductor moving through a
  magnetic field will produce an electrical current
  transverse to the direction of the field and the
  conductor motion.
• In an explosive or propellant driven MHD device,
  the conductor is a plasma of ionised explosive or
  propellant gas, which travels through the
  magnetic field.
• Technical issues such as the size and weight of
  magnetic field generating devices required for
  the operation of MHD generators suggest that MHD
  devices will play a minor role in the near term.

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High Power Microwave Sources - The Vircator

• The fundamental idea behind the Vircator is that
  of accelerating a high current electron beam
  against a mesh (or foil) anode.
• Many electrons will pass through the anode,
  forming a bubble of space charge behind the anode
• Under the proper conditions, this space charge
  region will oscillate at microwave frequencies.
  If the space charge region is placed into a
  resonant cavity which is appropriately tuned,
  very high peak powers may be achieved.

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• Conventional microwave engineering techniques may
  then be used to extract microwave power from the
  resonant cavity.
• Power levels achieved in Vircator experiments
  range from 170 kilowatts to 40 Gig Watts over
  frequencies spanning the decimeter and
  centimetric bands.
• The two most commonly described configurations
  for the Vircator are the Axial Vircator (AV) ,
  and the Transverse Vircator (TV) .
• The Axial Vircator is the simplest by design, and
  has generally produced the best power output in
  experiments.

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• Technical issues in Vircator design are output
  pulse duration, which is typically of the order
  of a microsecond and is limited by anode melting,
  stability of oscillation frequency, often
  compromised by cavity mode hopping, conversion
  efficiency and total power output.
• Coupling power efficiently from the Vircator
  cavity in modes suitable for a chosen antenna
  type may also be an issue, given the high power
  levels involved and thus the potential for
  electrical breakdown in insulators.
• An axial Vircator is shown in the figure.

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Non-Nuclear EM BOMBS

• This sort of e-bomb has a fairly simple,
  potentially inexpensive design, illustrated
  below.
• The bomb consists 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.

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• Here's the sequence of events when the bomb goes
  off
• A switch connects the capacitors to the stator,
  sending an electrical current through the wires.
  This generates an intense magnetic field.
• A fuze mechanism ignites the explosive material.
  The explosion travels as a wave through the
  middle of the armature cylinder.
• As the explosion makes its way through the
  cylinder, the cylinder comes in contact with the
  stator winding. This creates a short circuit,
  cutting the stator off from its power supply.
• The moving short circuit compresses the magnetic
  field, generating an intense electromagnetic
  burst.

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It is a Non Lethal Weapon..

• Generally considered 'non-lethal weapons', these
  weapons are not directly responsible for the loss
  of lives .
• But the electromagnetic weaponry do however pose
  health threats to humans.
• Affects the human central nervous system
  resulting in physical pain, difficulty in
  breathing, vertigo, nausea, disorientation, or
  other systemic discomfort.

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• Light and repetitive visual signals can induce
  epileptic seizures.Vection and motion sickness
  can also occur.
• Cavitation, which affects gas nuclei in human
  tissue, and heating can result from exposure to
  ultrasound.
• Microwave pulses can also affect the epidermis
  generating a burn from as far as 700 yards

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Electronic Attack

• Electronic attack involves the use of the EM
  energy, or anti-radiation weapons to attack
  personnel, facilitites, or equipment with the
  intent of degrading, neutralizing, or destroying
  enemy combat capability.
• EA include communcations jamming, IADS
  suppression, DE/LASER attack, expendable decoys
  (e.g., flares and chaff), and counter radio
  controlled improvised explosive device

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• In modern warfare, the various levels of attack
  could accomplish a number of important combat
  missions without racking up many casualties. For
  example, an e-bomb could effectively neutralize
• Vehicle control systems
• Targeting systems, on the ground and on missiles
  and bombs
• Communications systems
• Navigation systems
• Long and short-range sensor systems

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• The modern research has taken EM weapons to such
  limits that they can easily ruin even the
  satellites orbiting around the earth.
• What is worse is that presently research is in
  progress in order to control the satellites of
  opponents for our use or to misguide them.
• As with modern military aircraft, naval surface
  combatants are fitted with a substantial volume
  of electronic equipment, performing similar
  functions in detecting and engaging targets and
  warning of attack.
• They are vulnerable to electromagnetic attack,
  if not suitably hardened.
• Should they be hardened, volumetric, weight and
  cost penalties will be incurred.

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• EMP weapons could be especially useful in an
  invasion of Iraq, because a pulse might
  effectively neutralize underground bunkers. Most
  of Iraq's underground bunkers are hard to reach
  with conventional bombs and missiles
• A nuclear blast could effectively demolish many
  of these bunkers, but this would destroy the
  surrounding areas.
• An electromagnetic pulse could pass through the
  ground, knocking out the bunker's lights,
  ventilation systems, communications -- even
  electric doors. The bunker would be completely
  uninhabitable.
• While EMP weapons are generally considered
  non-lethal, they could easily kill people if they
  were directed towards particular targets. If an
  EMP knocked out a hospital's electricity, for
  example, any patient on life support would die
  immediately

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The Delivery of Conventional Electromagnetic
Bombs

• The height of delivery of an EM BOMB by an
  aircraft depends on the type of activation,
  damage estimated and weight of the BOMB.
• The figure shows two different launch profiles
  for GPS/Inertial guided weapons.
• Fusing could be provided by a radar altimeter
  fuse to airburst the bomb, a barometric fuse or
  in GPS/inertial guided bombs, the navigation
  system.
• The warhead fraction could be as high as 85,
  with most of the usable mass occupied by the
  electromagnetic device and its supporting
  hardware

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Lethal Radius Depends on Frequency of Operation
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Defense against EM Bomb

• The most effective method is to wholly contain
  the equipment in an electrically conductive
  enclosure, termed a FARADAY CAGE, which prevents
  the electromagnetic field from gaining access to
  the protected equipment.
• It harmlessly routes the signal around the
  electronics inside, but the conductors inside
  must be insulated from spurious currents that are
  induced as the signal passes around the surface
  of the cage
• However most such equipment must communicate with
  and be fed with power from the outside world, and
  this can provide entry points via which
  electrical transients may enter the enclosure and
  effect damage

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• While optical fibers address this requirement for
  transferring data in and out, electrical power
  feeds remain an ongoing vulnerability.
• Hardened buildings employ the use of special EM
  gasketing on doors, special attention to
  conductive surfaces on the outside, and optical
  isolators on antennas.
• The electrical supply to a hardened building must
  be located at a surprising depth underground in
  order not to "couple" with the signal, and if the
  electrical supply is connected to a standard
  power grid, the EMP will send a large surge
  (large enough to burn out lightning arrestors)
  into the power supplies of sensitive electronics.

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Limitations Of EM BOMB

• Limited Range.
• Thermionic technology ( vacuum tube equipment)
  more resilient to the electromagnetic weapons
  effects than solid state devices.
• Radiating targets such as radars or
  communications equipment may continue to radiate
  after an attack even though their receivers and
  data processing systems have been damaged or
  destroyed.

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• Conversely an opponent may shut down an emitter
  if attack is imminent and the absence of
  emissions means that the success or failure of
  the attack may not be immediately apparent.
• EM absorption effect the HPM weapons to shorter
  radii than are ideally achievable in the K and L
  frequency bands.
• Should the delivery error be of the order of the
  weapon's lethal radius for a given detonation
  altitude, lethality will be significantly
  diminished.
• An inaccurately delivered weapon of large lethal
  radius may be unusable against a target should
  the likely collateral electrical damage be beyond
  acceptable limits

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CONCLUSION

• In the blink of an eye, electromagnetic bombs
  could throw civilization back 200 years  and
  terrorists can build them for only 400 ....