Window and cavity breakdown caused by high power microwaves
Hemmert, David J.
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The transmission of high power microwaves through dielectric windows is of essential importance in their use. When an interface window fails due to surface flashover and breakdown, the power can no longer be transmitted and may reflect back into the source, possibly damaging it. In the work reported here, the physical mechanisms of surface flashover and breakdown are investigated for power levels of 10 MW/cm. A 3 MW magnetron and an S-band traveling wave resonator are coupled to produce 100 MW at 2.85 GHz in a high vacuum environment. A window geometry is established to provide a purely tangential electric field along the window surface. High speed diagnostics include forward, reverse, and local field power levels, x-ray emission, and discharge luminosity and imaging. Investigations into other window geometries as well as surface coatings and vacuum-gas interfaces are possible.