Slotted-resonator gyrotron experiments

Gyrotron experiments in which a waveguide cavity with ten slots cut through the cavity wall is used have been conducted. The gyrotron used a magnetron injection gun operating at 65-75 kV and up to 10 A in 1-microsec pulsed operation. Both open configurations, where the radiation can partially leak out of the resonator through the slots, and a configuration where the radiation is trapped by a foil sheath wrapped around the outside of the resonator were used. The observed power levels, in the 10-kW range, are lower than the power generated with an unslotted cavity. The foil sheath configuration produced a result with nearly continuous frequency tuning observed in the frequency range of 186.3-200.6 GHz (7.47-8.04 T). The frequency pulling due to changes in the magnetic field at the cathode or at the resonator was significantly larger than has been typically observed in an unslotted cavity. Frequency tuning due to changes in the parallel electron beam velocity was observed. This device has potential applications in the development of an electronically tunable gyrotron source.