Experimental demonstration of W-band gyroklystron amplifiers with improvedgain and efficiency

The experimental demonstrations of two W-band gyroklystron amplifiers are r eported. A four-cavity amplifier operating near 93 GHz achieved 84-kW peak output power and 34% efficiency for a 56-kV 4.4-A electron beam, The measur ed full-width at half maximum (FWHM) bandwidth was 370 MHz. A five-cavity g yroklystron amplifier produced 72-kW peak output power and 27% efficiency w ith 410-MHz FWHM bandwidth centered at 93.4 GHz with 50-dB saturated gain. Both,amplifiers were zero-drive stable at the operating points. The results from both experiments are compared with theory and good agreement is obtai ned.