Multiple beam klystron development for TESLA

Summary form only given, as follows. Progress to date is reported on the development of a 10 MW, 1300 MHz multiple beam klystron for the TESLA superconducting linear accelerator. A multiple beam klystron will be used because of its ability to produce high rf output powers A moderate electron beam energies. In this device, low cathode current density loading and hence longer cathode life is achieved by the use of off-axis electron beams. Beam bunching occurs in a series of separate fundamental mode klystron cavities whereas drive power input and output power extraction occur in large over-moded cavities for power combination reasons. The essential parameters of the device are 114 kV beam energy, 131 A beam current (21.8 A per beam), 65% efficiency, 50 dB gain and 150 kW of average rf output power.