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    E bomb seminar report E bomb seminar report Document Transcript

    • E- bomb Seminar Report ’031. INTRODUCTION The next Pearl Harbor will not announce itself with a searing flash ofnuclear light or with the plaintive wails of those dying of Ebola or its geneticallyengineered twin. You will hear a sharp crack in the distance. By the time youmistakenly identify this sound as an innocent clap of thunder, the civilized worldwill have become unhinged. Fluorescent lights and television sets will gloweerily bright, despite being turned off. The aroma of ozone mixed withsmoldering plastic will seep from outlet covers as electric wires arc andtelephone lines melt. Your Palm Pilot and MP3 player will feel warm to thetouch, their batteries overloaded. Your computer, and every bit of data on it, willbe toast. And then you will notice that the world sounds different too. Thebackground music of civilization, the whirl of internal-combustion engines, willhave stopped. Save a few diesels, engines will never start again. You, however,will remain unharmed, as you find yourself thrust backward 200 years, to a timewhen electricity meant a lightning bolt fracturing the night sky. This is not ahypothetical, son-of-Y2K scenario. It is a realistic assessment of the damage thatcould be inflicted by a new generation of weapons--E-bombs. Anyone whos been through a prolonged power outage knows that its anextremely trying experience. Within an hour of losing electricity, you develop aDept. of EEE 1 MESCE Kuttippuram
    • E- bomb Seminar Report ’03healthy appreciation of all the electrical devices you rely on in life. A couplehours later, you start pacing around your house. After a few days without lights,electric heat or TV, your stress level shoots through the roof. But in the grandscheme of things, thats nothing. If an outage hits an entire city, and there arentadequate emergency resources, people may die from exposure, companies maysuffer huge productivity losses and millions of dollars of food may spoil. If apower outage hit on a much larger scale, it could shut down the electronicnetworks that keep governments and militaries running. We are utterly dependenton power, and when its gone, things get very bad, very fast. An electromagnetic bomb, or e-bomb, is a weapon designed to takeadvantage of this dependency. But instead of simply cutting off power in an area,an e-bomb would actually destroy most machines that use electricity. Generatorswould be useless, cars wouldnt run, and there would be no chance of making aphone call. In a matter of seconds, a big enough e-bomb could thrust an entirecity back 200 years or cripple a military unit.2. BASIC PRINCIPLE-THE EMP EFFECT The Electro Magnetic Pulse (EMP) effect was first observed during theearly testing of the theory of electromagnetism. The Electromagnetic Pulse is ineffect an electromagnetic shock wave.Dept. of EEE 2 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 This pulse of energy produces a powerful electromagnetic field,particularly within the vicinity of the weapon burst. The field can be sufficientlystrong to produce short lived transient voltages of thousands of Volts (i.e.kilovolts) on exposed electrical conductors, such as wires, or conductive trackson printed circuit boards, where exposed. It is this aspect of the EMP effect which is of military significance, as itcan result in irreversible damage to a wide range of electrical and electronicequipment, particularly computers and radio or radar receivers. Subject to theelectromagnetic hardness of the electronics, a measure of the equipmentsresilience to this effect, and the intensity of the field produced by the weapon, theequipment can be irreversibly damaged or in effect electrically destroyed. Thedamage inflicted is not unlike that experienced through exposure to closeproximity lightning strikes, and may require complete replacement of theequipment, or at least substantial portions thereof. Commercial computer equipment is particularly vulnerable to EMPeffects, as it is largely built up of high density Metal Oxide Semiconductor(MOS) devices, which are very sensitive to exposure to high voltage transients.What is significant about MOS devices is that very little energy is required topermanently wound or destroy them, any voltage in typically in excess of tens ofVolts can produce an effect termed gate breakdown which effectively destroysDept. of EEE 3 MESCE Kuttippuram
    • E- bomb Seminar Report ’03the device. Even if the pulse is not powerful enough to produce thermal damage,the power supply in the equipment will readily supply enough energy tocomplete the destructive process. Wounded devices may still function, but theirreliability will be seriously impaired. Shielding electronics by equipment chassisprovides only limited protection, as any cables running in and out of theequipment will behave very much like antennae, in effect guiding the highvoltage transients into the equipment. Computers used in data processing systems, communications systems,displays, industrial control applications, including road and rail signaling, andthose embedded in military equipment, such as signal processors, electronicflight controls and digital engine control systems, are all potentially vulnerable tothe EMP effect. Other electronic devices and electrical equipment may also be destroyedby the EMP effect. Telecommunications equipment can be highly vulnerable,due to the presence of lengthy copper cables between devices. Receivers of allvarieties are particularly sensitive to EMP, as the highly sensitive miniature highfrequency transistors and diodes in such equipment are easily destroyed byexposure to high voltage electrical transients. Therefore radar and electronicwarfare equipment, satellite, microwave, UHF, VHF, HF and low bandDept. of EEE 4 MESCE Kuttippuram
    • E- bomb Seminar Report ’03communications equipment and television equipment are all potentiallyvulnerable to the EMP effect. It is significant that modern military platforms are densely packed withelectronic equipment, and unless these platforms are well hardened, an EMPdevice can substantially reduce their function or render them unusable.3. THE TECHNOLOGY BASE FOR CONVENTIONAL ELECTROMAGNETIC BOMBS The technology base which may be applied to the design ofelectromagnetic bombs is both diverse, and in many areas quite mature. Keytechnologies which are extant in the area are explosively pumped FluxCompression Generators (FCG), explosive or propellant driven Magneto-Hydrodynamic (MHD) generators and a range of HPM devices, the foremost ofwhich is the Virtual Cathode Oscillator or Vircator. A wide range ofexperimental designs have been tested in these technology areas, and aconsiderable volume of work has been published in unclassified literature. This paper will review the basic principles and attributes of thesetechnologies, in relation to bomb and warhead applications. It is stressed that thistreatment is not exhaustive, and is only intended to illustrate how the technologybase can be adapted to an operationally deployable capability.Dept. of EEE 5 MESCE Kuttippuram
    • E- bomb Seminar Report ’033.1. EXPLOSIVELY PUMPED FLUX COMPRESSION GENERATORS The FCG is a device capable of producing electrical energies of tens ofMega Joules in tens to hundreds of microseconds of time, in a relatively compactpackage. 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 microwavetubes. To place this in perspective, the current produced by a large FCG isbetween ten to a thousand times greater than that produced by a typical lightningstroke. The central idea behind the construction of FCGs is that of using a fastexplosive to rapidly compress a magnetic field, transferring much energy fromthe explosive into the magnetic field. The initial magnetic field in the FCG prior to explosive initiation isproduced by a start current. The start current is supplied by an external source,such a high voltage capacitor bank (Marx bank), a smaller FCG or an MHDdevice. In principle, any device capable of producing a pulse of electrical currentof the order of tens of Kilo Amperes to MegaAmperes will be suitable.Dept. of EEE 6 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 A number of geometrical configurations for FCGs have been published.The most commonly used arrangement is that of the coaxial FCG. The coaxialarrangement is of particular interest in this context, as its essentially cylindricalform factor lends itself to packaging into munitions. In a typical coaxial FCG, a cylindrical copper tube forms the armature.This tube is filled with a fast high energy explosive. A number of explosive typeshave been used, ranging from B and C-type compositions to machined blocks ofPBX-9501. The armature is surrounded by a helical coil of heavy wire, typicallycopper, which forms the FCG stator. The stator winding is in some designs splitinto segments, with wires bifurcating at the boundaries of the segments, tooptimise the electromagnetic inductance of the armature coil. The intense magnetic forces produced during the operation of the FCGcould potentially cause the device to disintegrate prematurely if not dealt with.This is typically accomplished by the addition of a structural jacket of a non-magnetic material. Materials such as concrete or Fiberglass in an Epoxy matrixhave been used. In principle, any material with suitable electrical and mechanicalproperties could be used. In applications where weight is an issue, such as airdelivered bombs or missile warheads, a glass or Kevlar Epoxy composite wouldbe a viable candidate.Dept. of EEE 7 MESCE Kuttippuram
    • E- bomb Seminar Report ’03Dept. of EEE 8 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 It is typical that the explosive is initiated when the start current peaks.This is usually accomplished with an explosive lens plane wave generator whichproduces a uniform plane wave burn (or detonation) front in the explosive. Onceinitiated, the front propagates through the explosive in the armature, distorting itinto a conical shape (typically 12 to 14 degrees of arc). Where the armature hasexpanded to the full diameter of the stator, it forms a short circuit between theends of the stator coil, shorting and thus isolating the start current source andtrapping the current within the device. The propagating short has the effect ofcompressing the magnetic field, whilst reducing the inductance of the statorwinding. The result is that such generators will producing a ramping currentpulse, which peaks before the final disintegration of the device. Published resultssuggest ramp times of tens to hundreds of microseconds, specific to thecharacteristics of the device, for peak currents of tens of MegaAmperes and peakenergies of tens of Mega Joules. The current multiplication (i.e. ratio of output current to start current)achieved varies with designs, but numbers as high as 60 have been demonstrated. The principal technical issues in adapting the FCG to weaponsapplications lie in packaging, the supply of start current, and matching the deviceto the intended load. Interfacing to a load is simplified by the coaxial geometry ofcoaxial and conical FCG designs3.2. HIGH POWER MICROWAVE SOURCES - THE VIRCATORDept. of EEE 9 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 Whilst FCGs are potent technology base for the generation of largeelectrical power pulses, the output of the FCG is by its basic physics constrainedto the frequency band below 1 MHz. Many target sets will be difficult to attackeven with very high power levels at such frequencies; moreover focussing theenergy output from such a device will be problematic. A HPM device overcomesboth of the problems, as its output power may be tightly focussed and it has amuch better ability to couple energy into many target types. A wide range of HPM devices exist. Relativistic Klystrons, Magnetrons,Slow Wave Devices, Reflex triodes, Spark Gap Devices and Vircators are allexamples of the available technology base. The Vircator is of interest because itis a one shot device capable of producing a very powerful single pulse ofradiation, yet it is mechanically simple, small and robust, and can operate over arelatively broad band of microwave frequencies. The physics of the Vircator tube are substantially more complex thanthose of the preceding devices. The fundamental idea behind the Vircator is thatof accelerating a high current electron beam against a mesh (or foil) anode. Manyelectrons will pass through the anode, forming a bubble of space charge behindthe anode. Under the proper conditions, this space charge region will oscillate atmicrowave frequencies. If the space charge region is placed into a resonantDept. of EEE 10 MESCE Kuttippuram
    • E- bomb Seminar Report ’03cavity which is appropriately tuned, very high peak powers may be achieved.Conventional microwave engineering techniques may then be used to extractmicrowave power from the resonant cavity. Because the frequency of oscillationis dependent upon the electron beam parameters, Vircators may be tuned orchirped in frequency, where the microwave cavity will support appropriatemodes. Power levels achieved in Vircator experiments range from 170 kilowattsto 40 Gig Watts. The two most commonly described configurations for the Vircator are theAxial Vircator (AV) (Fig.3), and the Transverse Vircator (TV). The AxialVircator is the simplest by design, and has generally produced the best poweroutput in experiments. It is typically built into a cylindrical waveguide structure.Power is most often extracted by transitioning the waveguide into a conical hornstructure, which functions as an antenna.. Coupling power efficiently from theDept. of EEE 11 MESCE Kuttippuram
    • E- bomb Seminar Report ’03Vircator 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 electricalbreakdown in insulators.4. THE LETHALITY OF ELECTROMAGNETIC WARHEADS The issue of electromagnetic weapon lethality is complex. Unlike thetechnology base for weapon construction, which has been widely published inthe open literature, lethality related issues have been published much lessfrequently. While the calculation of electromagnetic field strengths achievable at agiven radius for a given device design is a straightforward task, determining akill probability for a given class of target under such conditions is not. This is for good reasons. The first is that target types are very diverse intheir electromagnetic hardness, or ability to resist damage. Equipment which hasbeen intentionally shielded and hardened against electromagnetic attack willwithstand orders of magnitude greater field strengths than standard commerciallyrated equipment The second major problem area in determining lethality is thatof coupling efficiency, which is a measure of how much power is transferredDept. of EEE 12 MESCE Kuttippuram
    • E- bomb Seminar Report ’03from the field produced by the weapon into the target. Only power coupled intothe target can cause useful damage.4.1. COUPLING MODES In assessing how power is coupled into targets, two principal couplingmodes are recognised in the literature:  Front Door Coupling occurs typically when power from an electromagnetic weapon is coupled into an antenna associated with radar or communications equipment. The antenna subsystem is designed to couple power in and out of the equipment, and thus provides an efficient path for the power flow from the electromagnetic weapon to enter the equipment and cause damage.  Back Door Coupling occurs when the electromagnetic field from a weapon produces large transient currents (termed spikes, when produced by a low frequency weapon) or electrical standing waves (when produced by a HPM weapon) on fixed electrical wiring and cables interconnecting equipment, or providing connections to mains power or the telephone network. Equipment connected to exposed cables or wiring will experience either high voltage transient spikes or standing waves which can damage power supplies and communications interfaces if these are notDept. of EEE 13 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 hardened. Moreover, should the transient penetrate into the equipment, damage can be done to other devices inside. A low frequency weapon will couple well into a typical wiringinfrastructure, as most telephone lines, networking cables and power lines followstreets, building risers and corridors. In most instances any particular cable runwill comprise multiple linear segments joined at approximately right angles.Whatever the relative orientation of the weapons field, more than one linearsegment of the cable run is likely to be oriented such that a good couplingefficiency can be achieved. It is worth noting at this point the safe operating envelopes of some typicaltypes of semiconductor devices. Manufacturers guaranteed breakdown voltageratings for Silicon high frequency bipolar transistors, widely used incommunications equipment, typically vary between 15 V and 65 V. GalliumArsenide Field Effect Transistors are usually rated at about 10V. High densityDynamic Random Access Memories (DRAM), an essential part of any computer,is usually rated to 7 V against earth. Generic CMOS logic is rated between 7 Vand 15 V, and microprocessors running off 3.3 V or 5 V power supplies areusually rated very closely to that voltage. Whilst many modern devices areequipped with additional protection circuits at each pin, to sink electrostaticDept. of EEE 14 MESCE Kuttippuram
    • E- bomb Seminar Report ’03discharges, sustained or repeated application of a high voltage will often defeatthese. Communications interfaces and power supplies must typically meetelectrical safety requirements imposed by regulators. Such interfaces are usuallyprotected by isolation transformers with ratings from hundreds of Volts to about2 to 3 kV. It is clearly evident that once the defence provided by a transformer, cablepulse arrestor or shielding is breached, voltages even as low as 50 V can inflictsubstantial damage upon computer and communications equipment. The authorhas seen a number of equipment items (computers, consumer electronics)exposed to low frequency high voltage spikes (near lightning strikes, electricalpower transients), and in every instance the damage was extensive, oftenrequiring replacement of most semiconductors in the equipment . HPM weapons operating in the centimetric and mill metric bands howeveroffer an additional coupling mechanism to Back Door Coupling. This is theability to directly couple into equipment through ventilation holes, gaps betweenpanels and poorly shielded interfaces. Under these conditions, any aperture intothe equipment behaves much like a slot in a microwave cavity, allowingmicrowave radiation to directly excite or enter the cavity. The microwaveDept. of EEE 15 MESCE Kuttippuram
    • E- bomb Seminar Report ’03radiation will form a spatial standing wave pattern within the equipment.Components situated within the anti-nodes within the standing wave pattern willbe exposed to potentially high electromagnetic fields. Because microwave weapons can couple more readily than low frequencyweapons, and can in many instances bypass protection devices designed to stoplow frequency coupling, microwave weapons have the potential to besignificantly more lethal than low frequency weapons.4.2. MAXIMISING ELECTROMAGNETIC BOMB LETHALITY To maximise the lethality of an electromagnetic bomb it is necessary tomaximise the power coupled into the target set. The first step in maximisingbomb lethality is is to maximise the peak power and duration of the radiation ofthe weapon. For a given bomb size, this is accomplished by using the mostpowerful flux compression generator (and Vircator in a HPM bomb) which willfit the weapon size, and by maximising the efficiency of internal power transfersin the weapon. Energy which is not emitted is energy wasted at the expense oflethality. The second step is to maximise the coupling efficiency into the target set.A good strategy for dealing with a complex and diverse target set is to exploitevery coupling opportunity available within the bandwidth of the weapon.Dept. of EEE 16 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 A low frequency bomb built around an FCG will require a large antennato provide good coupling of power from the weapon into the surroundingenvironment. Whilst weapons built this way are inherently wide band, as most ofthe power produced lies in the frequency band below 1 MHz compact antennasare not an option. One possible scheme is for a bomb approaching itsprogrammed firing altitude to deploy five linear antenna elements. These areproduced by firing off cable spools which unwind several hundred metres ofcable. Four radial antenna elements form a "virtual" earth plane around the bomb,while an axial antenna element is used to radiate the power from the FCG. Thechoice of element lengths would need to be carefully matched to the frequencycharacteristics of the weapon, to produce the desired field strength. A high powercoupling pulse transformer is used to match the low impedance FCG output tothe much higher impedance of the antenna, and ensure that the current pulse doesnot vapourise the cable prematurely. Other alternatives are possible. One is to simply guide the bomb veryclose to the target, and rely upon the near field produced by the FCG winding,which is in effect a loop antenna of very small diameter relative to thewavelength. Whilst coupling efficiency is inherently poor, the use of a guidedbomb would allow the warhead to be positioned accurately within metres of atarget. An area worth further investigation in this context is the use of lowDept. of EEE 17 MESCE Kuttippuram
    • E- bomb Seminar Report ’03frequency bombs to damage or destroy magnetic tape libraries, as the near fieldsin the vicinity of a flux generator are of the order of magnitude of the coercivityof most modern magnetic materials.Dept. of EEE 18 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 The first is sweeping the frequency or chirping the Vircator. This canimprove coupling efficiency in comparison with a single frequency weapon, byenabling the radiation to couple into apertures and resonances over a range offrequencies. In this fashion, a larger number of coupling opportunities areexploited. The second mechanism which can be exploited to improve coupling is thepolarisation of the weapons emission. If we assume that the orientations ofpossible coupling apertures and resonances in the target set are random inrelation to the weapons antenna orientation, a linearly polarised emission willonly exploit half of the opportunities available. A circularly polarised emissionwill exploit all coupling opportunities.Dept. of EEE 19 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 The practical constraint is that it may be difficult to produce an efficienthigh power circularly polarised antenna design which is compact and performsover a wide band. Some work therefore needs to be done on tapered helix orconical spiral type antennas capable of handling high power levels, and a suitableinterface to a Vircator with multiple extraction ports must devised. A possibleimplementation is depicted in Fig.5. In this arrangement, power is coupled fromthe tube by stubs which directly feed a multi-filar conical helix antenna. Animplementation of this scheme would need to address the specific requirementsof bandwidth, beam width, efficiency of coupling from the tube, while deliveringcircularly polarised radiation. Another aspect of electromagnetic bomb lethality is its detonation altitude,and by varying the detonation altitude, a tradeoff may be achieved between thesize of the lethal footprint and the intensity of the electromagnetic field in thatfootprint. This provides the option of sacrificing weapon coverage to achievekills against targets of greater electromagnetic hardness, for a given bomb size(Fig.7, 8). This is not unlike the use of airburst explosive devices. In summary,lethality is maximised by maximising power output and the efficiency of energytransfer from the weapon to the target set. Microwave weapons offer the abilityto focus nearly all of their energy output into the lethal footprint, and offer theability to exploit a wider range of coupling modes. Therefore, microwave bombsare the preferred choice.Dept. of EEE 20 MESCE Kuttippuram
    • E- bomb Seminar Report ’035. TARGETING ELECTROMAGNETIC BOMBS The task of identifying targets for attack with electromagnetic bombs canbe complex. Certain categories of target will be very easy to identify and engage.Buildings housing government offices and thus computer equipment, productionfacilities, military bases and known radar sites and communications nodes are alltargets which can be readily identified through conventional photographic,satellite, imaging radar, electronic reconnaissance and humint operations. Thesetargets are typically geographically fixed and thus may be attacked providing thatthe aircraft can penetrate to weapon release range. With the accuracy inherent inGPS/inertially guided weapons, the electromagnetic bomb can be programmed todetonate at the optimal position to inflict a maximum of electrical damage. Mobile and camouflaged targets which radiate overtly can also be readilyengaged. Mobile and re locatable air defence equipment, mobile communicationsnodes and naval vessels are all good examples of this category of target. Whileradiating, their positions can be precisely tracked with suitable ElectronicSupport Measures (ESM) and Emitter Locating Systems (ELS) carried either bythe launch platform or a remote surveillance platform. In the latter instance targetcoordinates can be continuously data linked to the launch platform. As most suchtargets move relatively slowly, they are unlikely to escape the footprint of theelectromagnetic bomb during the weapons flight time.Dept. of EEE 21 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 Mobile or hidden targets which do not overtly radiate may present aproblem; particularly should conventional means of targeting be employed. Atechnical solution to this problem does however exist, for many types of target.This solution is the detection and tracking of Unintentional Emission (UE),where transient emanations leaking out from equipment due poor shielding canbe detected and in many instances demodulated to recover useful intelligence.Termed Van Eck radiation [VECK85], such emissions can only be suppressed byrigorous shielding and emission control techniques. Whilst the demodulation of UE can be a technically difficult task toperform well, in the context of targeting electromagnetic bombs this problemdoes not arise. To target such an emitter for attack requires only the ability toidentify the type of emission and thus target type, and to isolate its position withsufficient accuracy to deliver the bomb. Because the emissions from computermonitors, peripherals, processor equipment, switch mode power supplies,electrical motors, internal combustion engine ignition systems, variable dutycycle electrical power controllers (thyristor or triac based), super heterodynereceiver local oscillators and computer networking cables are all distinct in theirfrequencies and modulations, a suitable Emitter Locating System can be designedto detect, identify and track such sources of emission.Dept. of EEE 22 MESCE Kuttippuram
    • E- bomb Seminar Report ’036. THE DELIVERY OF CONVENTIONAL ELECTROMAGNETIC BOMBS As with explosive warheads, electromagnetic warheads will occupy avolume of physical space and will also have some given mass (weight)determined by the density of the internal hardware. Like explosive warheads,electromagnetic warheads may be fitted to a range of delivery vehicles. Known existing applications involve fitting an electromagnetic warhead toa cruise missile airframe. The choice of a cruise missile airframe will restrict theweight of the weapon to about 340 kg, although some sacrifice in airframe fuelcapacity could see this size increased. A limitation in all such applications is theneed to carry an electrical energy storage device, egg a battery, to provide thecurrent used to charge the capacitors used to prime the FCG prior to itsdischarge. Therefore the available payload capacity will be split between theelectrical storage and the weapon itself. In wholly autonomous weapons such as cruise missiles, the size of thepriming current source and its battery may well impose important limitations onweapon capability. Air delivered bombs, which have a flight time between tensof seconds to minutes, could be built to exploit the launch aircrafts powersystems. In such a bomb design, the bombs capacitor bank can be charged by theDept. of EEE 23 MESCE Kuttippuram
    • E- bomb Seminar Report ’03launch aircraft enroute to target, and after release a much smaller onboard powersupply could be used to maintain the charge in the priming source prior toweapon initiation. An electromagnetic bomb delivered by a conventional aircraft can offer amuch better ratio of electromagnetic device mass to total bomb mass, as most ofthe bomb mass can be dedicated to the electromagnetic device installation itself.It follows therefore, that for a given technology an electromagnetic bomb ofidentical mass to an electromagnetic warhead equipped missile can have a muchgreater lethality, assuming equal accuracy of delivery and technologically similarelectromagnetic device design. A missile borne electromagnetic warhead installation will comprise theelectromagnetic device, an electrical energy converter, and an onboard storagedevice such as a battery. As the weapon is pumped, the battery is drained. Theelectromagnetic device will be detonated by the missiles onboard fusing system.In a cruise missile, this will be tied to the navigation system; in an anti-shippingmissile the radar seeker and in an air-to-air missile, the proximity fusing system.The warhead fraction (i.e. ratio of total payload (warhead) mass to launch massof the weapon) will be between 15% and 30%.Dept. of EEE 24 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 An electromagnetic bomb warhead will comprise an electromagneticdevice, an electrical energy converter and an energy storage device to pump andsustain the electromagnetic device charge after separation from the deliveryplatform. Fusing could be provided by a radar altimeter fuse to airburst the bomb,a barometric fuse or in GPS/inertially guided bombs, the navigation system. Thewarhead fraction could be as high as 85%, with most of the usable mass occupiedby the electromagnetic device and its supporting hardware. Due to the potentially large lethal radius of an electromagnetic device,compared to an explosive device of similar mass, standoff delivery would beprudent. Whilst this is an inherent characteristic of weapons such as cruisemissiles, potential applications of these devices to glide bombs, anti-shippingmissiles and air-to-air missiles would dictate fire and forget guidance of theappropriate variety, to allow the launching aircraft to gain adequate separation ofseveral miles before warhead detonation. The recent advent of GPS satellite navigation guidance kits forconventional bombs and glide bombs has provided the optimal means for cheaplydelivering such weapons. While GPS guided weapons without differential GPSenhancements may lack the pinpoint accuracy of laser or television guidedmunitions, they are still quite accurate and importantly, cheap, autonomous allweather weapons.Dept. of EEE 25 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 The importance of glide bombs as delivery means for HPM warheads isthreefold. Firstly, the glide bomb can be released from outside effective radius oftarget air defences, therefore minimising the risk to the launch aircraft. Secondly,the large standoff range means that the aircraft can remain well clear of thebombs effects. Finally the bombs autopilot may be programmed to shape theterminal trajectory of the weapon, such that a target may be engaged from themost suitable altitude and aspect. A major advantage of using electromagnetic bombs is that they may bedelivered by any tactical aircraft with a nav-attack system capable of deliveringGPS guided munitions. As we can expect GPS guided munitions to be becomethe standard weapon in use by Western air forces by the end of this decade, everyaircraft capable of delivering standard guided munitions also becomes a potentialdelivery vehicle for an electromagnetic bomb. Should weapon ballistic propertiesbe identical to the standard weapon, no software changes to the aircraft would berequired. Because of the simplicity of electromagnetic bombs in comparison withweapons such as Anti Radiation Missiles (ARM), it is not unreasonable to expectthat these should be both cheaper to manufacture, and easier to support in thefield, thus allowing for more substantial weapon stocks. In turn this makessaturation attacks a much more viable proposition.Dept. of EEE 26 MESCE Kuttippuram
    • E- bomb Seminar Report ’037. DEFENCE AGAINST ELECTROMAGNETIC BOMBS The most effective defence against electromagnetic bombs is to preventtheir delivery by destroying the launch platform or delivery vehicle, as is the casewith nuclear weapons. This however may not always be possible, and thereforesystems which can be expected to suffer exposure to the electromagneticweapons effects must be electromagnetically hardened. The most effective method is to wholly contain the equipment in anelectrically conductive enclosure, termed a Faraday cage, which prevents theelectromagnetic field from gaining access to the protected equipment. However,most such equipment must communicate with and be fed with power from theoutside world, and this can provide entry points via which electrical transientsmay enter the enclosure and effect damage. While optical fibres address thisrequirement for transferring data in and out, electrical power feeds remain anongoing vulnerability. Where an electrically conductive channel must enter the enclosure,electromagnetic arresting devices must be fitted. A range of devices exist,however care must be taken in determining their parameters to ensure that theyDept. of EEE 27 MESCE Kuttippuram
    • E- bomb Seminar Report ’03can deal with the rise time and strength of electrical transients produced byelectromagnetic devices. Reports from the US indicate that hardening measuresattuned to the behaviour of nuclear EMP bombs do not perform well whendealing with some conventional microwave electromagnetic device designs.Dept. of EEE 28 MESCE Kuttippuram
    • E- bomb Seminar Report ’03Dept. of EEE 29 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 It is significant that hardening of systems must be carried out at a systemlevel, as electromagnetic damage to any single element of a complex systemcould inhibit the function of the whole system. Hardening new build equipmentand systems will add a substantial cost burden. Older equipment and systemsmay be impossible to harden properly and may require complete replacement. Insimple terms, hardening by design is significantly easier than attempting toharden existing equipment. An interesting aspect of electrical damage to targets is the possibility ofwounding semiconductor devices thereby causing equipment to suffer repetitiveintermittent faults rather than complete failures. Such faults would tie downconsiderable maintenance resources while also diminishing the confidence of theoperators in the equipments reliability. Intermittent faults may not be possible torepair economically, thereby causing equipment in this state to be removed fromservice permanently, with considerable loss in maintenance hours during damagediagnosis. This factor must also be considered when assessing the hardness ofequipment against electromagnetic attack, as partial or incomplete hardeningmay in this fashion cause more difficulties than it would solve. Indeed, shieldingwhich is incomplete may resonate when excited by radiation and thus contributeto damage inflicted upon the equipment contained within it. Other than hardening against attack, facilities which are concealed shouldnot radiate readily detectable emissions. Where radio frequency communicationsDept. of EEE 30 MESCE Kuttippuram
    • E- bomb Seminar Report ’03must be used, low probability of intercept (i.e. spread spectrum) techniquesshould be employed exclusively to preclude the use of site emissions forelectromagnetic targeting purposes. Communications networks for voice, dataand services should employ topologies with sufficient redundancy and failovermechanisms to allow operation with multiple nodes and links inoperative. Thiswill deny a user of electromagnetic bombs the option of disabling large portionsif not the whole of the network by taking down one or more key nodes or linkswith a single or small number of attacks.8. EFFECTS OF E BOMB The United States is drawn to EMP technology because it is potentiallynon-lethal, but is still highly destructive. An E-bomb attack would leavebuildings standing and spare lives, but it could destroy a sizeable military. There is a range of possible attack scenarios. Low-level electromagneticpulses would temporarily jam electronics systems, more intense pulses wouldcorrupt important computer data and very powerful bursts would completely fryelectric and electronic equipment.Dept. of EEE 31 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 In modern warfare, the various levels of attack could accomplish a numberof 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 EMP weapons could be especially useful in an invasion of Iraq, because apulse might effectively neutralize underground bunkers. Most of Iraqsunderground bunkers are hard to reach with conventional bombs and missiles. Anuclear blast could effectively demolish many of these bunkers, but this wouldtake a devastating toll on surrounding areas. An electromagnetic pulse could passthrough the ground, knocking out the bunkers lights, ventilation systems,communications -- even electric doors. The bunker would be completelyuninhabitable. U.S. forces are also highly vulnerable to EMP attack, however. In recentyears, the U.S. military has added sophisticated electronics to the full range of itsarsenal. This electronic technology is largely built around consumer-gradesemiconductor devices, which are highly sensitive to any power surge. MoreDept. of EEE 32 MESCE Kuttippuram
    • E- bomb Seminar Report ’03rudimentary vacuum tube technology would actually stand a better chance ofsurviving an e-bomb attack. A widespread EMP attack in any country would compromise a militarysability to organize itself. Ground troops might have perfectly functioning non-electric weapons (like machine guns), but they wouldnt have the equipment toplan an attack or locate the enemy. Effectively, an EMP attack could reduce anymilitary unit into a guerilla-type army. While EMP weapons are generallyconsidered non-lethal, they could easily kill people if they were directed towardsparticular targets. If an EMP knocked out a hospitals electricity, for example,any patient on life support would die immediately. An EMP weapon could alsoneutralize vehicles, including aircraft, causing catastrophic accidents. In the end, the most far-reaching effect of an e-bomb could bepsychological. A full-scale EMP attack in a developed country would instantlybring modern life to a screeching halt. There would be plenty of survivors, butthey would find themselves in a very different world.9. LIMITATIONS OF ELECTROMAGNETIC BOMBSDept. of EEE 33 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 The limitations of electromagnetic weapons are determined by weaponimplementation and means of delivery. Weapon implementation will determinethe electromagnetic field strength achievable at a given radius, and its spectraldistribution. Means of delivery will constrain the accuracy with which theweapon can be positioned in relation to the intended target. Both constrainlethality. In the context of targeting military equipment, it must be noted thatthermionic technology (i.e. vacuum tube equipment) is substantially moreresilient to the electromagnetic weapons effects than solid state (i.e. transistor)technology. Therefore a weapon optimised to destroy solid state computers andreceivers may cause little or no damage to a thermionic technology device, forinstance early 1960s Soviet military equipment. Therefore a hard electrical killmay not be achieved against such targets unless a suitable weapon is used. This underscores another limitation of electromagnetic weapons, which isthe difficulty in kill assessment. Radiating targets such as radars orcommunications equipment may continue to radiate after an attack even thoughtheir receivers and data processing systems have been damaged or destroyed.This means that equipment which has been successfully attacked may still appearto operate. Conversely an opponent may shut down an emitter if attack isimminent and the absence of emissions means that the success or failure of theattack may not be immediately apparent.Dept. of EEE 34 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 An important factor in assessing the lethal coverage of an electromagneticweapon is atmospheric propagation. While the relationship betweenelectromagnetic field strength and distance from the weapon is one of an inversesquare law in free space, the decay in lethal effect with increasing distance withinthe atmosphere will be greater due quantum physical absorption effects. This isparticularly so at higher frequencies and significant absorption peaks due watervapour and oxygen exist at frequencies above 20 GHz. These will thereforecontain the effect of HPM weapons to shorter radii than are ideally achievable inthe K and L frequency bands. Means of delivery will limit the lethality of an electromagnetic bomb byintroducing limits to the weapons size and the accuracy of its delivery. Shouldthe delivery error be of the order of the weapons lethal radius for a givendetonation altitude, lethality will be significantly diminished. This is of particularimportance when assessing the lethality of unguided electromagnetic bombs, asdelivery errors will be more substantial than those experienced with guidedweapons such as GPS guided bombs. Therefore accuracy of delivery and achievable lethal radius must beconsidered against the allowable collateral damage for the chosen target. Wherecollateral electrical damage is a consideration, accuracy of delivery and lethalDept. of EEE 35 MESCE Kuttippuram
    • E- bomb Seminar Report ’03radius are key parameters. An inaccurately delivered weapon of large lethalradius may be unusable against a target should the likely collateral electricaldamage be beyond acceptable limits. This can be a major issue for usersconstrained by treaty provisions on collateral damage.Dept. of EEE 36 MESCE Kuttippuram
    • E- bomb Seminar Report ’0310. CONCLUSIONS Electromagnetic bombs are Weapons of Electrical Mass Destruction withapplications across a broad spectrum of targets, spanning both the strategic andtactical. As such their use offers a very high payoff in attacking the fundamentalinformation processing and communication facilities of a target system. Themassed application of these weapons will produce substantial paralysis in anytarget system, thus providing a decisive advantage in the conduct of ElectronicCombat, Offensive Counter Air and Strategic Air Attack. Because E-bombs can cause hard electrical kills over larger areas thanconventional explosive weapons of similar mass, they offer substantialeconomies in force size for a given level of inflicted damage, and are thus apotent force multiplier for appropriate target sets. The non-lethal nature of electromagnetic weapons makes their use far lesspolitically damaging than that of conventional munitions, and therefore broadensthe range of military options available. This paper has included a discussion of the technical, operational andtargeting aspects of using such weapons, as no historical experience exists as yetDept. of EEE 37 MESCE Kuttippuram
    • E- bomb Seminar Report ’03upon which to build a doctrinal model. The immaturity of this weaponstechnology limits the scope of this discussion, and many potential areas ofapplication have intentionally not been discussed. The ongoing technologicalevolution of this family of weapons will clarify the relationship between weaponsize and lethality, thus producing further applications and areas for study. E-bombs can be an affordable force multiplier for military forces whichare under post Cold War pressures to reduce force sizes, increasing both theircombat potential and political utility in resolving disputes. Given the potentiallyhigh payoff deriving from the use of these devices, it is incumbent upon suchmilitary forces to appreciate both the offensive and defensive implications of thistechnology. It is also incumbent upon governments and private industry toconsider the implications of the proliferation of this technology, and takemeasures to safeguard their vital assets from possible future attack. Those whochoose not to may become losers in any future wars.Dept. of EEE 38 MESCE Kuttippuram
    • E- bomb Seminar Report ’0311. REFERENCES 1. AAP1000-RAAF, DI(AF)AAP1000,The Air Power Manuel, SECOND EDITION,RAAF APSC, CANBERRA,1994 2. CAIRD85-CAIRD R.S, TEST OF AN EXPLOSIVE DRIVEN COAXIAL GENERATOR 3. IEEE PULED POWER CONFERENCE, pp 483, IEEE ,NEW YORK,1989 4. OWLER60-‘HE MARK 4 GENERATOR , DIGEST OF TECHNICAL PAPERS,7’th IEEE PULSED POWER CONFERENCE 5. HOEBERLING92-‘ADVANCES IN VIRTUAL CATHOD MICROWAVE SOURCES, IEEE TRANSACTION ON ELECTROMAGNETIC COMBATIBILITY 6. IEEE SPECTRUM JULY 2002 7. IEEE SPECTRUM MARCH 2003 8. IEEE SPECTRUM NOVEMBER 2002 9. IEEE SPECTRUM APRIL 2003 10. IEEE SPECTRUM NOVEMBER 2001Dept. of EEE 39 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 CONTENTS1. INTRODUCTION2. BASIC PRINCIPLE-THE EMP EFFECT3. THE TECHNOLOGY BASE FOR CONVENTIONAL ELECTROMAGNETIC BOMBS4. THE LETHALITY OF ELECTROMAGNETIC WARHEADS5. TARGETING ELECTROMAGNETIC BOMBS6. THE DELIVERY OF CONVENTIONAL ELECTROMAGNETIC BOMBS7. DEFENCE AGAINST ELECTROMAGNETIC BOMBS8. EFFECTS OF E BOMB9. LIMITATIONS OF ELECTROMAGNETIC BOMBS10. CONCLUSIONS11. REFERENCESDept. of EEE 40 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 ABSTRACT Electromagnetic bombs are Weapons of Electrical Mass Destruction withapplications across a broad spectrum of targets, spanning both the strategic andtactical. As such their use offers a very high payoff in attacking the fundamentalinformation processing and communication facilities of a target system. Themassed application of these weapons will produce substantial paralysis in anytarget system, thus providing a decisive advantage in the conduct of ElectronicCombat, Offensive Counter Air and Strategic Air Attack. Generators would beuseless, cars wouldnt run, and there would be no chance of making a phone call.In a matter of seconds, a big enough e-bomb could thrust an entire city back 200years or cripple a military unit. The basic principle used in an e-bomb iselectromagnetic pulse effect EMP effect can result in irreversible damage to a wide range of electricaland electronic equipment, particularly computers and radio or radar etc. havingmilitary importance. Commercial computer equipment is particularly vulnerableto EMP effects.The technology base which may be applied to the design ofelectromagnetic bombs is both diverse, and in many areas quite mature. Keytechnologies which are extant in the area are explosively pumped FluxCompression Generators (FCG), explosive or propellant driven Magneto-Dept. of EEE 41 MESCE Kuttippuram
    • E- bomb Seminar Report ’03Hydrodynamic (MHD) generators and a range of HPM devices, the foremost ofwhich is the Virtual Cathode Oscillator or Vircator.Dept. of EEE 42 MESCE Kuttippuram
    • E- bomb Seminar Report ’03 ACKNOWLEDGEMENT I extend my sincere thanks to Prof. P.V.Abdul Hameed, Head of the Department, Electronics and Communication Engineering, for providing me his invaluable guidance for the Seminar. I express my sincere gratitude to my Seminar Coordinator and Staff in Charge Mr. Manoj K, for his cooperation and guidance in the preparation and presentation of this seminar. I also extend my sincere thanks to all the faculty members of Electronics and Communication Department for their support and encouragement. Vishnu ViswanathDept. of EEE 43 MESCE Kuttippuram