Multimegawatt RF power sources for linear colliders

Issues associated with klystron design, the approaches taken at the Stanford Linear Accelerator Center (SLAC) and elsewhere, the available results, and future prospects are discussed. Conceptual designs for a future linear collider operating at 11.4 GHz call for peak RF power as high as 240 MW/m, with an accelerator length of 14 km. This results in requirements for microwave sources that cannot be met with existing microwave tubes. While some new tube concepts are being considered, work is proceeding at several laboratories in the US and abroad on conventional 100-MW klystrons for this application. The electron beam necessary for this power to be generated, unless carefully controlled, can easily cause intrapulse melting at the klystron output circuit. This, coupled with the need for good efficiency, high production yield, and long life, poses some difficult problems to the klystron designer.<>