Generation of high-power microwave pulses using a spherical superconducting cavity and interference-type switch

We have generated 150 kW pulses of 2 μsec duration at 8.2 GHz frequency by rapidly dumping the energy stored in a nearly spherical superconducting cavity of 1.5l volume. The cavity was constructed of copper and electroplated with lead. A small geometrical perturbation was introduced to define a polar axis and suppress some unwanted modes. The mode excited was a fairly pure TE320mode. Intrinsic Q values greater than 109were achieved at 1.7 K, which allowed an energy accumulation of ∼ 0.3 joule with a drive power of about 300 watts. Energy input and pulse extraction were both achieved through a single aperture coupled to a rectangular waveguide by an interference type switch and variable coupler.