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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. errl@IAL YSI: e .. tv Figure 2 shows an example of a Marx generator circuit. Figure 2. Example of Marx Generator Circuit TRANSFORMER BASED GENERATORS Transformer-based pulse generators have also been used for many years as prime power for HPM sources. Transformers with ferrite cores have been used successfully in sources with multigigawatt output powers at kilohertz repetition rates. Ferrite development is an area where substantial gains could be made in HPM sources. Typically, programs are under time or budget constraints and do not give adequate attention to this research. As a result, little or no progress in new ferrite materials for pulsed operation has been made. Ferrites with increased frequency ranges and increased saturation flux density are needed. Air core transformers are used at higher flux densities and are often of the resonant variety because of their decreased coupling levels. Resonant transformers develop peak voltages after multiple cycles owing to coupling effects. Dual-resonant air core pulse transformers are prevalent and require coupling coefficients of 0.8, producing peak secondary voltage and maximum energy transfer after an initial reverse voltage swing. In dual-resonant designs, two frequencies or resonant modes are generated, and the output is the superposition of the two modes. Transformer systems generally require the primary circuit to be matched or tuned to the secondary, or vice versa. EXPLOSIVELY DRIVEN GENERATORS Explosively driven generators, also called flux compression generators (FCGs), work by setting up a strong magnetic field between two conductors, usually by discharging a capacitor bank charged to high voltage through an inductive coil. A conducting hollow cylinder filled with high explosives is placed in the center of the coil, filling the region between the two conductors with magnetic flux. The explosives are then used to compress the initial magnetic flux by driving the conducting cylinder surface, which contains the flux, outward into the current carrying coil. Work done by the conductors moving against the magnetic field results in a huge increase in the EM energy. The additional energy comes from chemical energy stored in the explosives. Thus, FCGs essentially convert a portion of the chemical explosive energy into EM energy. The explosively driven conductor is called an armature, and the nondriven inductive coil of the generator is called the stator. Miniaturizing the generators and fine-tuning the magnetohydrodynamic aspects takes years and is still an area of intense research. Material properties under the enormous forces involved are also required for success. Many hours of research and computer code writing and testing go into the selection of every single material used. One problem with this form of HPM source is that of coupling t he energy to the load. Attempts to energize the load by direct generation often result in the development of excessive internal generator voltages and UNCLASSIFIED/ /FOR: OFFICiI.t.L: 11 &:li ODIL¥ 16
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