GYROTRON EXPERIMENTS EMPLOYING A FIELD-EMISSION ARRAY CATHODE

The design and operation of a field emission array (FEA) cathode and t he subsequent demonstration of the first FEA gyrotron are presented. U p to 10 mA from 30 000 tips was achieved reproducibly from each of ten chips in a gyrotron environment, namely, a vacuum 1 x 10(-8) mbar, -5 0 kV potential with multiple chip operation, The design parameters of the FEA gun were similar to those of a magnetron injection gun with an achievable electron beam current of 50-100 mA and measured power 720 W cw. Coherent microwave radiation was detected in both TE(02) at 30.1 GHz and TE(03) at 43.6 GHz, with a starting current of 1 mA.