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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/ /POlt OFFl@IAL lel§li 8PUs:lf LAMINATED Laminated insulation has been used in some very demanding appl ications in which size is of primary importance and very small repeating structures are required, including high-energy -density capacitors, high-voltage t ransformers, and high-voltage transmission lines or pulse-forming lines. Laminated insulation schemes make use of the nonlinearity of electrical breakdown strength with thickness mentioned earl ier for plastics. Such schemes offer the possibil ity of sign ificant improvements in state-of-the art insulation, including a reduction in the size and an increase in the energy density of high-voltage pulsed systems. As new and improved materials become available, the possibilities for such improvements will become more substantial. PLASTIC- PAPER-OIL With appropriate attention to process details, very high dielectric strength is routinely achieved using this lamination scheme. This is in fact the insulation method used in most high-voltage and high -energy-density capacitors, with the addition of foil layers on either side of the plastic (usually biaxially oriented polypropylene) to form the capacitor. Use of corona-processed oil dramatically improves the utility of this insulating scheme. The plastic is frosted on at least one side and, together with the very thin ( 1 mil or less) paper layer, allows the oil to penetrate throughout the volume during the impregnation process. Without the oil, the tightly wound plastic layers can become sealed around small volumes of air that will not be filled with oil, and breakdowns will occur. Once the paper is impregnated with the oil, tests have shown that it attains essentially the same dielectric strength as the oil. Often, vacuum and pressure are alternately applied to ensure full penetration of the oil into the full volume. It is vitally important that no bubbles or voids be left in the insulation volume. For this reason, once the insulating volume is ready for impregnation, it should be left under vacuum at slightly elevated temperature for at least 24 hours. Th is not only ensures air pockets are removed but also allows the removal of surface moisture from the plastic and paper, wh ich will also contribute to voltage breakdown. The paper not only aids impregnation but also serves as a path for residual charge to dissipate between voltage applications. The plastic has a very high surface resistivity, and some residua l charge can become trapped on the surface after each discharge, resulting in charged regions of different magnitudes and even polarities, which can eventually lead to dielectric failure. Using this insulation scheme with biaxially oriented polypropylene as the plastic and Shell Diala AX as the impregnating oil, average dielectric strength of more than 2.1 kV/mil and operating voltages higher than 1.3 MV have been attained in large volumes. PLASTIC- PAPER- EPOXY Since the oil is the weakest dielectric medium in the preceding insulation scheme, it is reasonable to assume that replacing it with a stronger dielectric medium can improve the overall dielectric strength. Another advantage of this scheme is that in the end we would have a solid insulated volume with the advantages mentioned earlier. Thus far, only smaller volumes (1 -2 gallons) have been successfully insulated with this scheme . The problem is that the increase in viscosity over the oil, although small, makes it more difficult to ensure that fu ll impregnation is achieved. Meanwhile, the programs for wh ich this scheme is desired insist on nearly 100-percent certainty of success. The most successful process to date involves using quarter-inch sections of 1-mil paper followed by quarter-inch open sections for each layer. Th is is a tedious task in large volumes but UNCLASSIFIED/ fFOA OFFICiIAk Wlilii 0PUs:¥ 6
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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.