The past decade has seen significant advances in the science and technology of high power microwave (HPM) sources (MW-GW) driven by pulsed-power/ high current electron beams. The applications of these high power microwave sources have expanded to advanced accelerators, defensive measures, including homeland security and countermeasures against improvised explosive devices. In particular, major strides have been made in relativistic magnetrons, with the recirculating planar magnetron (RPM) [1-4], transparent cathodes , mode-control cathodes for phase-locking , and other innovations. The RPM consists of two, linear, cavity-arrays coupled by recirculating sections. The central-cathode structure supplies much higher current than conventional, cylindrical magnetrons. Recent results from UM+s RPM-12a, a 1-GHz, double-coaxial extractor prototype, have demonstrated extracted microwave powers of 150 MW at peak efficiencies of 40%. A 6-extractor design with goals of 400 MW, at 50-60% efficiency is under construction. Simulations show promising results for a multi-frequency RPM in which two planar slow-wave structures are employed with different resonant frequencies. There have also been important developments in plasma-based techniques for mitigating the effects of HPM pulses on electronic components. Impressive results have been achieved by a consortium of universities in the rapid-cutoff of microwave pulses by plasma-limiters. This presentation will summarize the recent scientific developments in both HPM source development, as well as techniques to rapidly absorb or reflect these microwave pulses.
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* This material is based upon work supported by the Air Force Office of Scientific Research under grant #FA9550-10-1-0104, the Air Force Research Laboratory, the Office of Naval Research under grant number N00014-13-1-0566 and L-3 Communications Electron Devices Division.
# In collaboration with Y.Y. Lau, M. Franzi, G. Greening, D. Simon, P. Zhang, B.W. Hoff, D. French, and J.W. Luginsland.