RF sources for future colliders

As we push particle colliders to 1-TeV center-of-mass collision energy and beyond, we require much more from our RF energy sources, both in terms of the RF performance and the number required for a given machine. In order to conserve real estate, the operating frequency of future colliders is apt to be higher than the S-band used for the SLAC SLC. It is this inevitable trend toward higher frequencies which presents the source designer with the greatest challenge. This paper is about that challenge. For reasons which will become clear, as we go to frequencies substantially above X-band, we will require sources other than klystrons, probably of the type referred to as open-quotes fast-wave devices,close quotes such as FEL or gyro-based amplifiers, or two-beam accelerators. Because these are discussed elsewhere in this conference, I will stick to the klystron as my model in describing the challenges to be overcome, as well as the criteria which must be met by alternative sources for new accelerators. copyright 1997 American Institute of Physics