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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/ /POil Offl61Ak Wlilii ,u1L¥ The Orion system, first fielded in 1995, is a self-contained, transportable HPM test facility housed in five standard shipping containers. It is computer controlled via fiberoptic links. The system is based on four continuously tunable magnetrons with a tunable frequency range of 1 to 3.3 GHz. The thyratron-switched modulator pulse charges an 11-section pulse-forming network through a step-up transformer and a triggered gas output switch. This provides a 100- to 500-ns pulse at 200 to 500 kV and up to 100 PRR that drives the magnetrons. The magnetrons are Figure 3. Orion HPM Testing Facility tuned by stepper-motors and use explosive emission cathodes. The vacuum of 10-6 to 10-7 is provided by cryopumps. The magnetic field of about 10 kG is provided by cryomagnets. The system includes an entire shipping container housing a combiner/attenuator network to provide continuously variable power over five orders of magnitude. The antenna is formed by two offset, shaped parabolic reflectors, each fed by two pyramidal horns. The antenna produces a 7 x 15 meter elliptical beam spot at a distance of 100 meters. Figure 3 shows the Orion test facility with its antenna. GYROTRONS Gyrotrons tap the energy associated with electrons gyrating about strong magnetic field lines. The main purpose for gyrotron development thus far has been magnetic confinement fusion research, in which megawatt-power, long-pulse gyrotron sources operating at more than 100 GHz provide resonant heating, current drive, and instability suppression. These devices use an electron gun to launch an electron beam into a region of slowly increasing magnetic field, where it is compressed. Compression raises the current density and produces a perpendicular component to the beam velocity. After compression, electron-guiding structures are placed at t he peak electric field position for the TE01 mode. The beam and guiding center structure then enter a resonant cavity. Inside the cavity, the electron motion decomposes into three components: a drift along the magnetic field lines, a slow rotation of the beam about ........ the magnetic axis owing to the 'H x 'B drift involving the beam self-electric field, and the Larmor rotation of individ ual electrons about the guiding centers. Resonant cavity fields oscillating faster than the rotational cyclotron frequency of electrons cause the electrons to bunch on one side of their common guiding centers. This bunching causes net electron energy to be given up to the cavity fields, which is then extracted. UNCLASSIFIED/ /FOR. errl@IAI:. Wlilii QIUL¥ 19
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