Development of X-band klystron technology at SLAC

The SLAC design for a 1-TeV collider (NLC) requires klystrons with a performance which is well beyond the state-of-the-art for microwave tubes in the United States or abroad. The electrical specifications for klystrons are not fully established, but approximately as follows: Frequency: 11.4 GHz Peak Power: 75 MW Pulse Length: 1.5 /spl mu/s Repetition Rate: 180 Hz Gain: 50 dB Efficiency: (including beam focusing) 50% SLAC is in the seventh year of a program to develop these klystrons. The choice of X-band as the operating frequency, along with the sheer size of the NLC, have resulted in some new, most demanding standards for the klystrons which may power this future machine. These are related to the overall efficiency required, to the high RF gradients that must be supported at the output circuit without vacuum breakdown, and to the manufacturing cost of the 5,000-10,000 klystrons needed for the collider.