Development of a Compact Narrow-band High Power Microwave System

A very Compact High Power Microwave system is developed at CEA Gramat. The 400 kV - 85 ns square pulse generation is provided by a compact and innovative PFN-Marx allowing a 100 pps repetition rate. Its low inductance design provides a very fast rise time and its U-shape output agrees with severe geometry constraints. This Marx is charged by a compact 45 kV capacitor charger, based on double resonance technology. The HPM source is an X-band sub-gigawatt relativistic resonant BWO using low magnetic field (0.6 T), allowing an optimized compactness. The antenna is a vacuum radial line with an array of helixes, providing high gain (>28 dB) and circular polarization, with a build-in TM01-TEM mode converter. This antenna fits in a very small volume (11 cm length and 42 cm in diameter, including mode converter). The entire assembled system (except batteries) has been experimented and characterized in the MELUSINE test area at CEA Gramat. A design study shows the possibility to integrate the entire system, including batteries and vacuum pumps, into a cubic volume of 65 cm side. Next phase will be the final integration, including prime power, into this limited space.