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This Defense Intelligence Reference Document (DIA-08-0912-005) is dated 28 January 2010. The Defense Intelligence Agency's Defense Warning Office prepared it under the Advanced Aerospace Weapon System Applications Program. It gives an overview of pulsed high-power microwave sources and the technologies needed to build them, including insulation, cathode materials, high-voltage switching, pulse generators and antennas. The paper concludes that progress requires better cathodes, switching and insulation, and that compact ultrawideband antennas will remain difficult to build.
From the source:Release of 2026-09-18 Incident: 1/28/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys pulsed high-power microwave (HPM) source technology and argues that such systems remain of military interest because they can disrupt or damage electronic systems with short, intense electromagnetic pulses. The report reviews the main source types and the supporting technologies they depend on, including high-voltage insulation, switching, cathode materials, antennas, and pulse-power generation. It emphasizes the difficulty of building systems that are compact, efficient, and practical to field, since short pulse durations, antenna size, heating, detectability, and beam or signal quality all impose hard engineering limits. Its overall conclusion is that the technology has significant potential military value, but that further progress depends on advances in cathodes, predictive modeling, high-speed high-voltage switching, and low-loss insulation, while compact ultrawideband systems will remain difficult because of basic physical constraints on antenna design.
UNCLASSIFIED/ /FOR OFFICl,CL l:ISI!!! 8HLY breakdown. One solution to these difficulties has been transformer-coupling the load by having the FCG drive the primary of a transformer. The load for HPM production is typically some type of loop antenna with very small inductance and driven directly from the generator. Much research has been done on the effectiveness of th is type of antenna, and one method of improving the operation is to fuse the loop along its length such that at peak current, the fuses open and radiate large voltage dl/dt spikes. Pulsed High-Power Microwave Sources Pulsed HPM sources can be divided into two types: • Pulsed electron beam sources - these are typically narrow-band HPM sources such as relativistic klystron amplifiers, backward wave oscillators, traveling wave tubes, split-cavity oscillators, reltron and super reltron, virtual cathode oscillators, magnetrons, gyrotrons, and the magnetically insulated line oscillator. • Impulse HPM sources - these are typically wideband or ultrawideband sources such as SNIPER, EMBL, Phoenix, Jolt, Thor, GEM II, and the H series. PULSED ELECTRON BEAM SOURCES In pulsed electron beam sources, the RF source includes an electron beam generator, a beam transport, and a wave structure. These sources work by converting the kinetic energy of an electron beam into EM energy. BWOs, TWTs, AND RKAs HPM tubes, such as backward wave oscillators (BWOs), travel ing wave tubes (TWTs), and relativistic klystron amplifiers (RKAs), are also very similar in concept to their conventional counterparts. The main differences lie in the techniques of beam formation; the use of pulsed, large magnitude axial magnetic fields for beam transport; and the application of relativistic voltages and very high beam currents. BWO efficiencies as high as 35 percent have been obtained at moderate power levels, but as power levels are increased, the output levels tend to saturate, and the radiated spectra tends to broaden. These effects are due to beam breakup and turbulent transport. To maintain high beam quality, large magnetic fields are required for high-power operation. An approximately 25- to 50-kG applied axial field implies that mechanically strong solenoidal magnets are required with pulsed capacitor banks to drive them. These requirements in turn dictate a much larger and heavier HPM source. TWTs can be made using many of the same techniques as BWOs. The difference is that the beam wave interaction is with a forward wave. Thus, TWTs have many of the same issues and limitations as BWO sources. RKAs use cavities for beam bunching and power extraction rather than continuous slow wave structures as in BWOs and TWTs. Some RKA designs use extended structures for power extraction to reduce the power densities and to increase efficiency. They use high beam currents where space charge forces become dominant in the bunching process. Tubes have been developed at the 10-GW power level. They use 0.5 to 1 MeV beams guided by axial magnetic fields of about 10 kG. Efficiencies are on the order of 40-50 percent. Some of the issues with these tubes are beam transport, beam loading of the cavities, base pressure of the vacuum system, x- UNCLASSIFIED/ /liOA: OfililCllL: Uiliii 0PU..Y 17
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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 37 pages are in the text index: search them above, or from the library's search.