A PPM klystron for accelerator service

An S-band six-cavity klystron employing periodic focusing and rated at 60 Kw at 0.002 duty has been developed. The tube design is based on an integral polepiece arrangement which serves to provide a magnetic field at the gaps without compromising the cavity design. The cavities are tunable and water-cooled. A perveance beam with a convergence of 18:1 is used. The beam transmission is 98 per cent but drops to 80 per cent at full drive. The klystron has been tested to power levels above 120 Kw and operates at an efficiency of 35 per cent. The gain is in excess of 60 db with a nominal 30 Mc bandwidth. Several of these tubes are in operation at the Stanford Project M Linear Accelerator.