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appears to have been repackaged intoa single been repackaged tohave appears butnow beeninthreesemitrailers, to initiallyhave directed MTHELwas MTHELsystem. the secondgeneration leadingto deployment, impractical foroperational madeit The sheerbulkofthedemonstrator point defenceSAMor AAA system. notunlikea the terminaldefenceofalocalarea, usedfor short-range weapon THEL isarelatively the Unlikethe ABL, targets anddirectthebeam. using aphasedarrayradartotrackincoming The THEL programyieldedexcellenttrial results, class weapon. ThiswasaMegaWatt White SandsinNewMexico. Systems Test Facility at (HELSTF Directorate) theHighEnergy trialled extensivelyafter1983at Thisresearch system was Director opticalturret. energy coupledtotheSeaLiteBeam , orMid-Infrared Advanced the USNavy’s MIRACL, The firstdeuteriumfluoridelasertobetrialledwas and toxicdeuteriumfluorideexhausteffluxgas. tosoakupthehighlycorrosive stage neutralisation including a systemmustbeused, equalisation complex exhaustdiffusionandpressure A such asthecarbondioxideGDLandCOIL. ofotherchemicallasers nozzles similartothat deuterium andheliumfedintoexpansion whichisthenmixedwith fluoride lasingmedium, weaponsTrifluoride gastoproducetheexciteddeuterium burns ethyleneintoxicandcorrosiveNitrogen Thecombustorinthislaser microns wavelength. 3.8 at deuterium fluoridechemicallaseroperating The demonstrator THEL systemwasbuiltarounda by mortar. including asalvoattack shells andmortarrounds, multipleartillery rockets, and 160mmKatyusha 28122mm destroying between 2000and2004, The wastrialledrepeatedly THEL demonstrator aircraft. flying mortarroundsandlow shells, artillery rockets(Katyushas), artillery and destroying ofengaging iscapable that point defenceweapon The designaimofthe THEL systemsistoprovidea T Energy WeaponsEnergy Directed Dr CarloKopp (MTHEL). Mobile THEL andrelocatable THEL baseline thestatic configurations, THEL istobebuiltintwo The in1996. the programinitiated with developed bytheUSandIsrael, he jointly THEL isalaserweapon Tactical Laser(THEL) HighEnergy ground basedair defence overthecomingdecade. of a viableproductand islikelytobecomeafeature MTHEL development effortissustainedandyields Thecurrent change thegamefundamentally. whichissetto unlikethe ABL, be determined, termstheimpactof the In strategic THEL isyetto common. impediments aremuchmore similar propagation cloud low and fog, environments wheremoistair, tropical environmentsornortherntemperate tobetrue forhumid thesameisnotapt operations, may be optimalfor THEL climatic conditions, desert withdry WhileIsrael, physics. atmospheric imposed by limitations andpropagation weather the THEL/MTHEL suffersthesame Like the ABL, RAFAEL and Tadiran. fire controlsystem), IAI/Elta(whodevelopedtheradarand Elbit/El-Op, Ball Aerospace, including TRW/Northrop-Grumman, The THEL/MTHEL systemwasdevelopedbyateam timelines. funding difficultiesandthusuncertaintiesin by2007butmorerecentreportsindicate deployed Aprototypewasto be container-sized semitrailer. The YAL-1A ABL prototype carried in a Boeing 747- Boeing a in carried prototype ABL YAL-1A The 400F airframe of the . Air States United the of airframe 400F right: Close-up of the ABL optical turret subsystem, turret optical ABL the of Close-up right: used to direct the lethal near-infrared beam at targets, at beam near-infrared lethal the direct to used using a large primary mirror. primary large a using analyse remaining US high energy laser weapons programs. laserweapons analyse remainingUShighenergy Inthisfinalpartwe groundbreaking US Air Force YAL-1A ABL program. andthe oflasersasweapons, technical difficultiesfacedintheadapation the Weapons wecoveredtheearlydevelopmentofairbornelasers, In thefirsttwopartsofthisspecialreportonlethalDirectedEnergy part 3 Advanced Tactical Laser (ATL) multimillion dollar investment in alone. In practical terms, HELLADS is to produce a 750 kg The ATL program is an effort to exploit the Public reports on this program largely vanished laser capable of producing 150 killoWatts of power, technology developed for the ABL to provide a over the last three years, suggesting it is no longer compact enough to be carried by aircraft, ground cheaper and smaller system suitable for carriage funded. vehicles and UAVs. The technology is a liquid laser, on aircraft such as the AC-130 Spectre or V-22 in which the lasing medium is a fluid containing the Osprey, as a close air support weapon. In January High Energy Liquid Laser Area active chemical species pumped for laser action. this year, the US Air Force’s 46th Test Wing provided Defense System No details of the design concept have been Boeing with a C-130H Hercules for trials of the The High Energy Liquid Laser Area Defense System released so far but it is reasonable to speculate that prototype weapon, claimed to be in the MegaWatt (HELLADS) effort was launched following a the liquid is actively cooled, thus avoiding the class, which uses COIL technology. The intent is to research breakthrough by DARPA in 2003, with a problems inherent in solid state lasers. The pump mount the laser prototype in the aircraft and budget of around US$75M. Its aims were described mechanism has not been disclosed. If pumping is perform lethality trials in 2007 against a range of by the US DoD thus: performed using laser diodes, it is reasonable to ground targets. L-3 Communications/Brashear ‘The goal of the High Energy Liquid Laser Area speculate that the liquid also cools the pump developed the optical turret, and the laser is being Defense System (HELLADS) program is to develop lasers. built by AFRL at in a high-energy system (~150 kW) General Atomics is the prime contractor, with Albuquerque, New Mexico. with an order of magnitude reduction in weight Lockheed Martin providing integration. HELLADS compared to existing laser systems. With a weight will, like the ABL, use a wavefront sensor and active Solid State High Energy Laser goal of less than 5 kg/kW, HELLADS will enable mirror technology for beam wavefront correction. A demonstration is planned for 2007. An alternative HEL technology now under high-energy lasers (HELs) to be integrated onto development is the solid state electrically pumped tactical aircraft and will significantly increase laser, popularised extensively in 2002 as part of the engagement ranges compared to ground-based Summary Joint Strike Fighter marketing campaign. systems. The HELLADS program has completed The next ten years will see the emergence of high This category of laser is based on the humble laser design of a revolutionary high energy laser that energy lasers as an operational capability in US diode, which first emerged twenty years ago as a supports the goal of a lightweight and compact Forces’ service. These weapons will have the technology for use in optical fibre communications. high energy laser weapon system. An objective unique capability to attack targets at the speed of Laser diodes are evolved siblings of the common system laser module with integrated power and light and are likely to significantly impair the Light Emitting Diode (LED) found in household thermal management will be fabricated and effectiveness of many weapon types, especially appliances and now even battery powered torches. demonstrated at an output power of 15 kW. Based ballistic weapons. Constrained by propagation Light emitting diodes, usually made from Gallium on the results of this demonstration, additional physics, these weapons will not provide all weather based alloys, generate light as a result of electrical laser modules will be developed and integrated capabilities, and will perform best in clear sky dry current flow through a minute semiconductor with a beam control subsystem to produce a 150 air conditions. junction, which has been doped with additives kW laser weapon system demonstrator. The Australia needs to carefully analyse and monitor which become excited by the electrical conditions performance of the demonstrator will be the development and deployment of this class of in the junction. An LED is an incoherent and characterized in a laboratory environment. weapons, as they have the potential to be highly relatively broad emitter compared to a laser. Program Plans call for the following developmental valuable for a number of niche roles. They will, Current LED technology spans colours from milestones: however, not be a panacea. infrared through to blue. The distinction between an - Develop and test a 15 kW objective system laser LED and Laser Diode is that the latter is fabricated module with integrated power and thermal Editor’s Note: Other beam weapons such as management subsystems. Laser Induced Plasma Channel, anti-personnel with a miniature optical resonator to induce Millimetric Wave systems, and electromagnetic oscillation and thus laser action. To narrow the - Complete preliminary design of a 150 kW laser bombs will be discussed in a future article, as bandwidth of the cavity, most communications weapon system. these are not technically speaking, directed lasers now also include a diffraction grating in the - Complete detailed design and fabricate a 150 kW energy weapons. design, in addition to the resonant cavity. A simple laser weapon system. description of a laser diode is that it is a special - Demonstrate performance of a 150 kW HEL type of LED designed to exhibit laser action. At this system.’ time Laser diodes are manufactured in vast quantities for CD and DVD burners and also for communications and industrial applications. The solid state laser effort led by the US Air Force at the Air Force Research Lab aims to develop a 25 kiloWatt weapon, scalable to 100 kiloWatts and suitable for carriage by aircraft, ground vehicles and ships as a close-in weapon. The attraction of this technology is that electrical power is easy to supply and toxic propellants are not required. The idea behind these high power lasers is to couple together a very large number of much smaller laser diode modules, which then pump the laser medium with energy. This is essentially a scaled-up equivalent to the laser dioded pumped 1.55 micron eyesafe rangefinding lasers now in use. The principal problems currently faced with this technology are cost, scalability and power handling Clockwise from right: capability. Conversion efficiency from electrical THEL engagement scenario. power to optical output for these systems is typically of the order of 10 per cent, which means A 160 mm Katyusha artillery rocket engaged that 90 per cent of the electrical power put into the by the THEL system. laser is converted into waste heat, which needs to be removed. The individual laser diodes are also THEL optical turret subsystem. Note the cassegrainian primary aperture (US Army). not very powerful, typically emitting around one Watt each. A laser rated at 25 kW with a 10 per cent conversion efficiency would require 250,000 diodes. At $10 per diode, this results in a

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