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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/ /POR. OPPl@IAL l:ISE 8Ptllf HIGH-SPEED LIQUID SWITCHING Liquid switching has also been used in UWB HPM sources with great success. The same phases of breakdown exist for liquid switches as do for gas switches. The electrode spacing is typically smaller for liquid switches, and electrodes can be made smaller for the same level of energy transfer owing to greater thermal diffusion to the liquid as compared with a gas. Liquid switching does not have the extreme safety concerns associated with gas switching; however, for repetitively pulsed operation, flow of the liquid insulating media is required. Filtering, evacuation, and processing may also be required. Liquid switches have achieved rise times of less than 100 ps and PRRs of 1,500 pulses per second. SOLID- STATE SWITCHING Solid-state switches have seen some improvement in voltage holdoff capability but generally still do not have the capability of operating at tens of kilovolts required of HPM sources. The current technology in lateral gallium arsenide (GaAs) switches is greatly improved compared with the old bulk avalanche semiconductor switch technology of the last decade. The power handling capabilities of this technology are impressive; however, it still suffers from short lifetimes because of heat dissipation problems. Source designs using GaAs switches typically involve an array of horns with one switch per horn. The array can then be phased in time to allow steering of the beam. GaAs switches operate at about 10 kV and, therefore, in the large arrays required, several switches fail during any burst mode operation. The most promising new developments in semiconductor switches today are based on physics pioneered by I. V. Grekhov and colleagues at the Ioffe Physical-Technical Institute in St. Petersburg. The AFRL is currently collaborating with Dr. Grekhov and the University of New Mexico in studies of delayed breakdown devices, silicon avalanche shapers, and drift step recovery diodes in efforts to improve the performance of these devices. It is also investigating the use of silicon carbide as an alternative to silicon and GaAs. State-of the art pulse generators using these devices currently are capable of 6-8 kV output with 100-ps rise times and 20-ps switching jitter. Conventional solid-state devices such as junction gate field-effect transistors (JFETs) have not seen substantial improvement and operate at about a kilovolt with rise times of a few nanoseconds, making them useful for trigger supplies but not in HPM sources. Photoconductive solid-state (PCSS) switching is still of great interest because of the inherent advantages it could provide. PCSS switches have very low jitter, have fast rise times, and are compact. This technology, sufficiently developed, could allow design of HPM sources with fewer compression stages, allow greater frequency agility and pulse width adjustment, and be used in arrays by phasing many lower power sources together. The technology's main limitations at present are power handling and a limited lifetime. PCSS switches have three modes of operation. In the linear mode, one electron-hole pair is generated by each photon absorbed, and so the conductivity is linearly proportional to the incident photon flux. Linear mode PCSS switches are made from silicon, doped GaAs, and indium phosphide. The electrical pulse output follows the amplitude of the optical trigger pulse. Switching in this mode requires about 1 mJ/cm 2 of optical energy and thus requires a larger laser trigger tha n do other operating modes. PCSS switches also operate in a lock-on mode in which once the optical trigger causes conduction, carriers remain as long as current still flows, even if the optical UNCLASSIFIED//FOR OFFICIO I.: Uili &Nit:¥ 14
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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.