DOW-UAP-D121, AAWSAP DIRD, Pulsed High-Power Microwave Source Technology, January 2010

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Pulsed High-Power Microwave Source Technology Prepared by: Acquisition Support Division (DW0-3) Defense Warning Office Directorate for Analysis Defense Intelligence Agency AAP Person 64 Administrative Note COPYRIGHT WARNING: Further dissemination of the photographs in this publication is not authorized. This product is one in a series of advanced technology reports produced in FY 2009 under the Defense Intelligence Agency, Defense Warning Office's Advanced Aerospace Weapon System Applications (AAWSA) Program. Comments or questions pertaining to this document should be addressed to !AAP Person 1 AAWSA Program Manager, Defense Intelligence Agency, ATTN: CLAR/DW0-3, Bldg 6000, Washington,

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Uniform Homogeneous....................................................................................... 2 Urethanes and Silicones ................................................................................. 4 Cesium Iodide Coated ...................................................................................... 10 High-Speed Liquid Switching............................................................................ 14 High-Voltage Pulse Sources ................................................................................. 15 Transformer Based Generators ........................................................................ 16

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Explosively Driven Generators ......................................................................... 16 Pulsed High-Power Microwave Sources................................................................ 17 Pulsed Electron Beam Sources ......................................................................... 17 Virtual Cathode Oscillators............................................................................... 18 The Phoenix HPM Source.................................................................................. 22 Narrowband Antennas...................................................................................... 25 Wideband and Ultrawideband Antennas........................................................... 27 Figure 1. Paschen Curve for Air ............................................................................ 13 Figure 2. Example of Marx Generator Circuit ........................................................ 16 Figure 4. Active Denial System With FLAPS Antenna ............................................ 20 Figure 5. H2 With Large TEM Horn and PGC Output.............................................. 21 Figure 6. Cross-Section Drawing of HS With Point Geometry Converter, Brewster Angle Window, and Extended-Ground-Plane Antenna ........................... 21 Figure 7. HS Output Section With the Point Geometry Converter Feeding an Extended-Ground-Plane Antenna Through a Brewster Angle Window ... 22 Figure 8. Phoenix Radiated Pulse at 8.5 Meters ................................................... 23 Figure 9. Phoenix Radiated Spectral Content ....................................................... 23

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Figure 11. Jolt Radiated Electric Field Waveform at 85 Meters ............................. 24 Figure 12. FLAPS Antenna With a Cross-Shorted Dipole Array ............................. 26 Figure 13. Mode Converter Vlasov Antenna and Vlasov Antenna Attached to a Table 1. Dielectric Properties of Some HPM Plastics............................................... 3 Table 2. Relative Spark Breakdown Strength of Gases ........................................... S

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Pulsed High-Power Microwave Source Technology This paper provides an overview of the major types of high-power microwave (HPM) sources and the critical technologies required to build them. Pulsed HPM technology has been of scientific and military interest for several decades. Originally, the interest focused on the area of high-altitude electromagnetic pulse (HEMP) concerns. HEMP is produced when a nuclear weapon is detonated high above the earth's surface, creating gamma radiation that interacts with the atmosphere to create an intense electromagnetic (EM) energy field that is harmless to people as it radiates outward but can overload computer circuitry with effects similar to, but causing damage more swiftly than, a lightning strike. HEMP effects became fully known in 1962, when a high-altitude nuclear test (codenamed "Starfish Prime") over the Pacific Ocean disrupted radio stations and electronic equipment 800 miles away in Hawaii. The HEMP effect can span thousands of miles, depending on the altitude, design, and power of the nuclear burst. It is speculated that a single device detonated at high altitude over the central United States could affect the entire country, since the HEMP would be picked up by conductors, such as wires and power cables, acting as antennas to conduct the electrical energy into various electronic systems. This EM radiation was found to have field levels on the order of several hundreds of kilovolts per meter with onset or rise times of a few nanoseconds and a duration of nearly a microsecond. Fields of these magnitudes were found to have severe detrimental effects on numerous electrical systems and items, such as the power grid, automobiles, communications equipment, and aircraft. Much testing was done in the 1960s and 1970s to determine vulnerabilities and to find mitigation solutions. The HEMP is essentially a wideband microwave pulse, and several EMP simulators were devised and built for use in testing its effect on various electronic systems. In addition, several programs were established to investigate the possibility of generating and radiating other spectrums of EM radiation that may have some of these same effects without requiring a nuclear detonation. This was the impetus for the advancement of pulsed HPM technologies for weapons. HPM radiation is composed of shorter waveforms at higher frequencies than is HEMP, which makes it highly effective against electronic equipment and more difficult to harden against. Whereas HEMP weapons are large in scale and require a nuclear capability along with technology to launch high-altitude missiles, HPM weapons are smaller in scale, involve a much lower level of technology, and are within the capability of almost any state. HPMs can damage computers and electronics similar to the way HEMP can, although the effects are limited to a much shorter range. Technical accessibility, lower cost, and the vulnerability of U.S. electronic equipment could make small-scale HPM weapons attractive to terrorist groups. HPM devices are now categorized as directed-energy weapons.

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One major use of HPM by the military is for electronic attack, or what is referred to by the media as an "ebomb." HPM sources developed for this purpose provide peak powers in excess of 10 gigawatts. The goal of such a weapon is to disable communications and computer systems prior to any troop movements and render the enemy unable to stage a response. The technology used to drive such sources has its roots in pulsed power, and for narrowband sources requires the use of tools that have been developed in the plasma physics community. Reliance on microprocessors that have an increasing density of circuits packaged onto each chip makes such systems ever-more vulnerable to HPM effects. As an example of the possible effects of HPM weapons, on 28 May 2001, a U.S. Commanche helicopter, flying in New York state while performing tests involving HPM weapons, was reported to have generated a low-level energy pulse that disrupted the Global Positioning System devices used to land commercial aircraft in Albany. The use of this type of weapon can be based on several scenarios, depending on the asset it will be used against. Sometimes, it may only be necessary to upset a data bus transfer to produce a success; other times, success may not