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Defense Intelligence Reference Document Pulsed High-Power Microwave Source Technology

Defense Intelligence Agency · 37 pages · text from the file's own layer

This Defense Intelligence Reference Document from the Defense Intelligence Agency, dated 28 January 2010, surveys pulsed high-power microwave (HPM) source technology. It was produced under the Advanced Aerospace Weapon System Applications (AAWSA) program. It covers insulation, cathode materials, high-voltage switching, pulse generators, microwave sources such as magnetrons, gyrotrons and the Phoenix and Jolt sources, and antennas. The document concludes that progress depends on advances in cathodes, switching and insulation. It says compact ultrawideband antennas will remain difficult to build.

Open the PDF at page 37 Original source ↗

“The Times”17 pages

  • p. 6 …on the order of several hundreds of kilovolts per meter with onset or rise times of…
  • p. 7 …If the pulse duration is short compared with thermal diffusion times, then the temperature increases in…
  • p. 8 …The short burst mode operation is necessary because of the high peak powers and subsequent heating…
  • p. 17 …Second, it has a fast turn-on time. Third, the insulating nature of the velvet fibers…
  • p. 18 …As a result, the HPM emission times have been extended. Typically, the cesium salt is dissolved…
  • p. 19 …The period of the lowest frequency is twice the pulse width, and the rise time is…
  • p. 20 …Thus, the faster the rise time and the wider the pulse, the broader the spectral content…
  • p. 21 …8FF11il.t.k WE&i a••k>/ rise time is the time required to heat the…
  • p. 22 …The array can then be phased in time to allow steering of the beam. GaAs switches…
  • p. 24 …The explosives are then used to compress the initial magnetic flux by driving the conducting cylinder…
  • p. 26 …SPLIT-CAVITY OSCILLATORS Split-cavity oscillators (SCOs) utilize transit-time bunching of the beam to generate…
  • p. 28 …in the 3.5-ns-wide pulse is 1.25 GW, and the rise time is…
  • p. 29 …Thus, for H3 the FOM is 250 kV. While developing the H series of HPM sources…
  • p. 30 …Phoenix had the fastest rise time of any HPM source to date. Figure 8 shows the…
  • p. 32 …By timing the switching sequence of each BASS module, the beam was steerable up to 30…
  • p. 35 …Thus, if the frequency chirps during the RF pulse, then the beam direction will sweep. The…
  • p. 36 …This is why the rise time of the driving pulse is so important to antenna response…
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Conclusion
This paper provided an overview of the current state of HPM sources and the
technologies driving their development. Advanced cathode materials, computer codes
for more predictive ability in electron beam generation and propagation, high-speed
switching at high power, and low-loss insulation techniques are just a few of the areas
where advancement clearly is needed for progress to occur. Advancements in
photoconductive solid-state (PCSS) and other solid-state switching and sharpening
devices appear to finally be reaching a level of development such that they may soon
be of use in high-voltage systems. If PCSS switching devices capable of higher
operating voltage and extended lifetime are made available, variations of the phased
array will become the HPM source design of choice, given the inherent advantages.
More compact antennas are greatly desired; however, the physics of the radiation
process requires structure sizes on the order of one-half wavelength of the lowest
radiated frequency. With demanding levels of directivity and gain also requirements,
compact UWB antenna designs will continue to be difficult, if not impossible, to realize.
29
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Report, from the dia collection. The PDF is mirrored here; the original link is under it. 37 pages are in the text index: search them above, or from the library's search.