The future of klystrons

Summary form only given, as follows. The klystron is the oldest of the microwave tubes, but continues to be essential to a number of user communities, principally that of experimental physics, which was also responsible for its invention. The advent of traveling-wave tubes and of the transistor has limited the uses of the klystron to applications requiring a high pf/sup 2/ product. For those applications, it remains the amplifier of choice, particularly if cost is considered. The paper describes some new klystron configurations and their potential future. These include multi-beam and sheet-beam klystrons, PPM klystrons, and millimeter-wave klystrons, mass-produced with lithographic techniques.